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Germany: Environmental History – European Regional Smog from Peat-Swamp Burning (IFFN No. 18)

Environmental History:
European Regional Smog from Peat-Swamp Burning in Germany

(IFFN No. 18 – January 1998, p. 59-60)

Historic Moor Cultivation

In the 18th century the landscape of Northern Germany was dominated by large uncultivated bogs and swamps. In 1770 about 1/7 of the total area of Niedersachsen was uncultivated bogs. The common people were afraid of these ‘dark and wild’ places and tried to stay away from these areas, which were perceived to be haunted. But with the population growth of the end of the 18th century, people were forced to enlarge the area under production and started to cultivate these areas. To fulfill their plans they began to burn the bogs.

Burning Methods

The chosen plots for the new settlement must first be drained and levelled of. This work was done in autumn with the establishment of ditches which were laid out in such a way that the plot was divided into long narrow strips. The purpose of this work was to dry out the plot for further treatment. In spring of the following year, the upper organic layer of the bog was removed with big hoes, and the duff was cut out in quadratic clods. If the year was very wet this work was done in early autumn. In these wet years the ground had to be broken up several times.

In May work requiring strong men began: the clods had to be thrown and stacked into little piles. Thereafter these piles of stacked and dried clods were ignited. As soon as the material was half-burned, the still burning pieces were distributed against the wind all over the field. The fire had to burn for several days at calm weather for several days. It was very important that the fire be watched over so that it did not penetrate the deeper organic layers. The bog area only had to burn slightly or, in other words, smoulder. This work was extremely strenuous and the workers’ clothes were covered with ash and dust, while their eyes were constantly a shade of red during the burns.

The burning of the bog began mainly in mid-May and ended in June. The drying of the organic material and the heat caused the normally barely accessible plant nutrients of the bog to break up enabling the cultivation of oat and buckwheat on the freshly burned fields, without fertilization.

The burning of the bogs was however not possible on the same plot year after year, over a longer period of time. In general a single plot was burned and tilled over a period of six to seven years. After the cultivation period a fallow period of 20 years was necessary. For this reason shifting cultivation was practised, where thereafter a neighbouring plot was used for the next 6 to 7 years, after which new land was then cultivated.

The burning of bogs was first noted in the year 1583. At that time the regional administrator (Drost) of the Emsland enacted a strict ordinance against this kind of “cultivation”.

In 1669 similar ordinances existed in the counties of Oldenburg and Delmenhorst. In 1720 the following was written: “In the Emsland the farmers are not willing to desist burning the bogs. They rather would pay the fine and continue to burn.”

The first stimulus for the agricultural use of the moor came from the Netherlands. The upper organic layer of the moor was used for peat production and afterwards the dismantled moor was cultivated (“Fehn” cultivation).

Burning practices were introduced as well from the Netherlands to Eastern Friesland and spread from there throughout northwest German bog areas.

The “Dry Fog”

The burning of the bogs had an oppressive effect on the northwest German areas, even in areas far away. This effect, the “smell of burning” was known under the term “High Smoke”. What is “High Smoke”? Why was the smoke of the bogs called “High Smoke”?

The bog researcher Racke wrote: “The dark, thick and heavy, evil-smelling smoke covered the land for miles. In the spring often in the shape of a high dark wall, it rapidly gathers like a storm-cloud and covers the sun so that it looks like a dim disc. At more favourable conditions the smoke escapes, and the longer it travels the weaker it gets, ending as haze, carried into areas far away as Hungary or Southern France. In Germany this phenomenon is called “Heerauch”, “Haarrauch”, “Höhenrauch” and is hardly liked. Public opinion made it responsible for all sorts of damage. It is said that it drives away rain. The farmers of the “Alte Land” said that it damages the blossoms of fruit trees, and that it should even drive melancholical people to suicide.” For years the inhabitants of countries far away from the actual bog burns were puzzled over the origin of the recurring smoke. The French, for example, thought that the “brouillard sec” was dried fog. The English called the bogsmoke “dry fog”. The puzzlement did not stop:

In 1657 the bog burnings began on 6 May in Northern Friesland carried by strong easterly winds. Already on the next day the smoke had reached Utrecht, and a little bit later had changed direction, passing Leeuwarden towards Den Helder reaching the sea on 15 May. There, the wind changed suddenly northwest and drove the bog smoke back, so that on 16 May it had reached Utrecht and Nijmwegen again. At the same time the smoke was also noticed in Hannover, Münster, Köln, Bonn, and Frankfurt. On 17 May the smoke reached Vienna, on the 18th May Dresden and Krakau on 19 May.

Johann G. Goldammer (Editor IFFN)

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Fig. 1 Moor burning in Friesland around the turn of the century. Smoke from these land-use fires sometimes covered large areas of Europe.

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24. November 2017/by GFMCadmin

Germany: Fire in Nature Conservation and Management: Changing Paradigms? (IFFN No. 18)

Fire in Nature Conservation and Management:
Changing Paradigms?

(IFFN No. 18 – January 1998, 69-72)

While no substantial changes in the field of forest fire management can be reported from Germany (see forest fire statistics update in Table 1), some recent developments in nature conservation are shaking the foundations of German landscape management. Interestingly enough, this is happening at the time of the publication of Stephen J. Pyne’s comprehensive analysis of the cultural history of European fire “Vestal Fire” in which he states:

“Europe’s peculiar geography and dense demographics, and the intensity of its agricultural reclamation gave European fire a special character. Europe’s temperate core – not shaped by well-defined fire season – granted humans an unusual degree of control over fire, and encouraged the belief that fire was, in principle, a strictly human agency, that it was a convenient tool but not an essential process. If fire’s importance was instrumental and ceremonial, it could be replaced by less volatile technologies and more modern rites, much as wheat replaced weedy brome and draft oxen replaced wild aurochs. Fire was, so the saying went, a good servant but a bad master.”

“The keepers of Europe’s flame accepted this condition as normative. They distrusted free-burning fire and sought to cultivate it from landscape and ultimately replace it with the industrial combustion of fossil fuels. Europe came itself to resemble a fire in which a burned-out core smoldered, aglow with random embers, while flames propagated along its perimeter, not only the margins of western Eurasia but the colonial periphery to which Europe carried the torch. The geography and dynamics of fire on the contemporary Earth is largely a consequence of European expansion, the impact of an imperial Europe and an industrial Europe. Europe’s fire became as much a standard of reference for fire practices as Greenwich mean time for the world’s watches or SI units for global physics.”

“Germany is a controlled landscape. It has to be, given its population pressures. The German nature reserves constitute only 1.1 percent of the national landmass, with 200 of them less than 5 hectares in size, other restricted landscapes amount to 18 percent. None tolerate fire. Even outside theses zones, agricultural burning is rigorously proscribed to specific seasons. The burning of hedges, in particular, has aroused strong condemnation over the centuries because it breaks down the careful borders of political and propertied world, another illustration of fire as manifestation of social disorder. That perception describes perfectly the difference between landscape organized as a house instead of an ecosystem. Behind these fears lay the memory of the war’s fire catastrophe.”

His statements are right. In the very geographical centre of Europe – in Germany – the post-World War II development continued to perfectly eradicate some key factors which are vital elements of the cultural heritage of landscapes and biodiversity. The cultural landscapes and vegetation patterns of Central Europe are the result of hundreds of years of intensive utilization of the land. Cutting, mowing, grazing and burning were the methods used for harvesting timber and fuelwood, improving site conditions, growing domestic livestock by stimulating and regenerating desirable grasses, herbs and bushes, and by removing non-desirable, moribund and dead plant biomass. Like elsewhere in the world, our ancestors practised slash-and-burn methods which had a similar physiognomy all over Europe and followed principles similar to the swidden agricultural systems of the tropics.

In Germany, systems of rotating swidden agriculture were part of a forest utilization cycle, known as Reuteberge (Rüttibrennen), Birkenberg– and Haubergwirtschaft, which created a mosaic of forest, open grazing and agricultural lands, with all the successional stages in between. Within the Black Forest region (Southwest Germany) swidden agriculture was practised on ca. 70,000 ha by the middle of the 19th Century. After World War II – around 1950 – this system was still alive on ca. 10,000 ha.

Regular burning of juniper grasslands in South Germany and on heathlands (Calluna) in North Germany was quite common until the late 19th century. The intensive utilization of heathland by sheep grazing and the use of raw humus for stables and fuel supply resulted in the creation of nutrient-poor sites. These sites, however, provided ecological niches – habitats – for a variety of plant and animal species.

Ignoring the fact that Central Europe’s face has been shaped by traditional practices in agriculture, pastoralism and forestry over hundreds of years, nature conservationists and landscape planners attempted to preserve this heritage by excluding land-use methods. The creation of completely protected refugia for nature, embedded in a rapidly growing post-modern industrial society, was built on the vision that the preservation of nature and biodiversity could be reached only with the exclusion of all disturbances. This policy soon turned out to be a misconception. The heathlands of North Germany, rich in biodiversity and popularity, as mediated by the romantic writer Hermann Löns, began to change: With every hectare abandoned by sheep and shepherds’ fires the forest reconquered the terrain. Monotonous pine forests began to replace the flowering heathlands.

This misconception became visible at a large scale with the changing socio-economic conditions of post-war Europe and the increasing influence of European and global markets on the national agricultural sector. High production costs – as compared to the competitive international economies and markets – and incompatibility with the demands of a modern industrial society led to a dramatic decrease in the utilization of vegetative matter. While a similar process in the Mediterranean countries provided the fuels for more and more intensive wildland fires, afforestation of abandoned farm lands became a regular practice in rural Germany. Only a restrictive practice of issuing afforestation permits halted the tendency of steadily growing forest cover and the loss of variety in traditional landscape patterns. Abandoned sites which landscape architects wanted to keep open, e.g. for recreation reasons (hiking, skiing), had to be treated through subsidies by the government. Mowing, mulching and grazing in accordance with landscape plans, however, soon became prohibitively expensive.

Ironically, all this became most visible at the end of the Cold War. The reduction of military stationed on German territory set free a tremendous amount of military surplus. Large military exercise areas in former East and West Germany were abandoned and put under nature protection laws. With the retreat of the military exercise gunfire and manoeuvres the disturbances disappeared. Soon it was recognized that the impact of fire and heavy vehicles had been most important in continuously halting and creating new succession opportunities for a rich subclimax species variety. In other words: With increasing protection and the exclusion of disturbances, diversity began to decline.

Increasing costs for large-scale landscape gardening all over Germany, the dramatic challenges of vegetation utilization on former military areas, on marginal sites and steep terrain, on extremely small patches, e.g. hedge strips, between intensively used agricultural and viticultural sites – important refugia for species that could not survive in the chemo-technical environment of industrial agriculture, created new discussions about maintaining the cultural heritage.

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Fig. 1. Prescribed fire in the Kaiserstuhl viticulture area, Southwest Germany: First experiments in January 1998. Photo: Fire Ecology Research Group.

It was only about two years ago that ecologists and nature conservationists in Germany began to think about restoring the use of fire in those landscapes that had been treated with fire historically and which were threatened by the exclusion of all disturbance. Within 1996-97 a fire revolution swept over the offices of the public administrations and the media. While the public is concerned by seeing the threatening smoke come out of Southeast Asia and local farmers are still punished for the illegal use of fire, fire scientists began to sort out the pros and cons of restoring fire in maintaining biodiversity and landscape aesthetics. Within less than a year four scientific workshops were held at the State Academies for Nature Conservation in Lower Saxony, Hesse, and Baden-Württemberg, and finally, in August 1997, the Federal German Nature Conservation Academy held a workshop on “Restoration of Dynamic Processes in Nature Conservation”, in which fire played a key issue. In 1997 the first large prescribed burning research program began in the State of Baden-Württemberg, aiming to investigate the use of prescribed burning in the management of hedge and slope terrain in the viticulture region of Southwest Germany (Fig.1). The use of fire to maintain or restore grass cover, a habitat for endangered flora and fauna, is the objective of a program which is driven by the dramatically increasing costs for subsidized landscape gardening and the fact that many of the vulnerable sites have been lost to the succession towards bush and tree cover.

The changing paradigm in nature conservation in Germany is clearly visible. The signals emitted by nature conservation fires clearly show that the fire ban imposed on German landscapes in the mid-1970s cannot be kept any longer. The solutions, however, must consider the manifold sensitivities of industrial society, in which high awareness on environmental issues determines day-to-day politics.

Tab. 1. Forest fire statistics of Germany 1977-96: Causes, number of fires, area burned, and economic damage.
Source: Federal German Ministry for Agriculture and Food.

Year	Arson		Neglicence		Other		Lightning		Unknown		Total		Damage
Year	#	Area burned (ha)	#	Area burned (ha)	#	Area burned (ha)	#	Area burned (ha)	#	Area burned (ha)	#	Area burned (ha)	#	Area burned (ha)
1977 *	172	80	384	151	248	215	2	0	294	167	1100	613	2.5	4078
1978 *	94	32	212	76	157	103	8	0	163	78	634	289	1.2	4152
1979 *	75	34	219	79	203	154	2	0	201	89	700	356	1.2	3371
1980 *	132	57	471	368	375	886	4	1	388	233	1370	1545	3.8	2450
1981 *	125	33	255	143	79	207	1	0	184	114	644	497	2.5	5030
1982 *	223	138	441	164	198	327	3	1	379	121	1244	751	3.7	4927
1983 *	197	92	296	150	227	256	22	1	367	293	1109	792	6.7	8460
1984 *	183	105	460	264	148	303	2	0	370	203	1163	875	5.1	5829
1985 *	146	47	163	67	72	86	2	0	139	42	522	242	1.3	5372
1986 *	146	36	151	48	121	152	5	1	195	56	618	293	1.4	4778
1987 *	99	41	168	136	105	96	2	0	110	46	484	319	1.6	5016
1988 *	143	21	164	48	104	86	6	0	142	127	559	282	1.4	4965
1989 *	237	64	192	39	135	117	12	1	230	60	806	281	1.8	6406
1990 *	225	86	311	131	152	146	28	6	285	113	1001	481	10.5	21830
1991	460	127	395	245	333	309	11	4	647	236	1846	920	3.3	3587
1992	550	309	710	680	386	1,274	133	966	1,233	1,679	3,012	4,908	25,0	5,093
1993	385	178	466	444	112	119	79	11	652	740	1,694	1,493	10,6	7,099
1994	345	170	485	352	111	84	131	50	624	459	1,696	1,114	2,6	3,334
1995	273	149	345	230	40	18	51	15	528	180	1,237	592	2,9	4,899
1996	334	204	555	477	133	300	16	1	710	400	1,748	1,381	8,2	5,937
% Change in 1996 as compared to 1995:
	22	37	61	108	233	1552	-69	-93	34	122	41	133	184	21

* Only former Federal Republic of Germany (West Germany)

From: Johann G. Goldammer (Editor IFFN)

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24. November 2017/by GFMCadmin

Germany: Autonomous Early Warning System for Forest Fires Tested in Brandenburg (Germany) (IFFN No 22 – January 2000)

Autonomous Early Warning System for Forest Fires
Tested in Brandenburg (Germany)

(IFFN No. 22 April 2000, p. 84-90)

Abstract

Forest fires cause significant economic damage and hazard to environment all over the world. Apart from preventive measures, early warning and fast extinction of fires are the only chance to avoid major casualties and damage to nature, especially in regions with dense population. As a common method, trained staff observes the endangered areas. In Germany alone, several hundred observation towers were erected in the forests. The staff works up to 12 hours per day and usually under difficult circumstances (extreme temperatures, isolation, continuous concentration).

To date, all attempts to develop a technical system for this task have failed to outlast the test stage. In most cases the chosen components do not work reliable enough. The Autonomous Early Warning System For Forest Fires AWFS described herein is based on new concepts of hard- and software. It is adapted to the specific conditions in densely wooded regions and detects fire by the trail of smoke.

AWFS consists of a rotating digital camera with a special filter and an innovative electronic system. Thus, an utmost high level of reliability is achieved. The noise is extremely low and allows high radiometric resolution (14bit). Digital data are transmitted from the camera to the computer via optical fibers and get evaluated. The necessary software forms the central component of the system. It recognizes smoke almost in real time by analyzing its typical dynamic and stochastic features. This became possible by modifying know-how gained in space projects. However, only recent development of fast CPUs and high capacity storage media allowed to finally solve complex problems of real-time picture processing at low cost. Warnings are autonomously passed over to a central unit, where an operator will evaluate them. For this purpose, comprehensive and user-optimized software was developed. It visualizes all information necessary for taking further steps and assists in decision-making.

AWFS was installed and tested on three observation towers in Brandenburg, Germany, during the 1999 forest fire season. It became apparent that the main requirement for absolute reliable smoke detection was met. The false alarm rate due to weather and harvest activities commonly remained below 1%, which is well acceptable. Other improvements will be effective soon. The testing forest authority confirmed that the system is mature for service and easy to use. The number of systems will be increased therefore. Moreover, other German states and some European countries are very interested in this technology.

Introduction

The probability of fires in forests and fields is steadily increasing due to climate changes and human activities. In Europe, up to 10,000 km² of vegetation are destroyed by fire every year, and even 20,000 to 90,000 km² in North America. Prognoses presume from the assumption that forest fires including fire clearing in tropical rain forests will halve the worlds forest stand by 2030. Vegetation fires result in high human death toll, speed up the extinction of species and worsen the greenhouse effect. Approximately 20 % of the CO2 emissions into the atmosphere are released by forest fires, estimated the Enquiry commission “Prevention To Save The Earth Atmosphere” of the German Bundestag in 1990. Germany, too, will be affected by the impacts of global climate change. In Brandenburg and some other German states enormous economic damage is caused by forest fires. For instance, in Brandenburg alone more than 1,000 forest fires are registered every year. 90 % of them are caused by human activities. Large fires cause a total damage of up to 70,000 DM/ha. The annual financial loss caused by forest fires in Germany amounts to a two-digit number of millions. However, preventive and fire extinction measures cost even several times this sum.

In order to minimize damage, forest fires must be recognized as soon as possible (within a few minutes). Therefore, great efforts are made in all respective regions to achieve early recognition. Although numerous technical methods were tested, reliability was in no case sufficient to develop a product suitable for the German market. As an example, infrared sensor systems tested in Spain can only detect the fire itself. However, smoke is the feature relevant for early recognition of fires in densely wooded areas. Optical systems as AWIS in the Netherlands (Breejen et al. 1998) and Firehawk in South Africa are also in a test phase. But they often imply a high rate of false alarm caused by clouds, light reflection, agricultural activities and industrial plants.

In Canada and Russia an early warning system based on aircraft patrolling is used, which means late recognition of forest fires though and is expensive to operate. Evaluating satellite data is also not very successful, as spatial and time resolution are not sufficient to allow local prevention. Moreover, clouds obstruct the view very often. . However, with the German project BIRD a new generation of imaging infrared sensors for Earth remote sensing objectives including is developed (Briess et al. 1999). A major intention of the BIRD is to demonstrate the scientific and technological value and the technical and programmatic feasibility of fire detection of under low-budget constraints. The start of this small satellite mission is planned for the end of year 2000. Within the European project FUEGO an operational mini satellite constellation is studied (Gonzalo 1996.). It will become operational in 2004 to provide early fire outbreak detection and high resolution fire-line monitoring. Hence to date experienced fire-watchers are employed everywhere in the world to observe endangered forests. In Germany several hundred observation towers are manned during main forest fire season. The fire-watchers observe the forests up to 12 hours per day under utmost difficult circumstances (extreme temperatures, awkward hygiene conditions, isolation, only short breaks from concentration) and report about any smoke formation. Apart from that, authorities usually have to spent large sums on the construction of observation towers, as these edifices need to be built, maintained and operated in accordance with relevant legislation and regulation. As an example, approximately DM 350,000 are required to build one observation tower in Brandenburg.

The pilot project “Autonomous Early Warning System For Forest Fires” (AWFS) was ordered and supported by the forest authority of Peitz, Brandenburg, and promoted by the European Union. It comprised installation and testing of a system for the following tasks:

Observe the forests autonomously and reliably for smoke formation

Recognize fires early, reduce the risk of human failure and thus minimize damage

Improve the working conditions of the staff

Reduce observation costs

A solution for this complex undertaking was found by further developing know-how from unmanned space missions and consistently adapting it to the problem of forest fire recognition.

Technical description of AWFS

According to the forest authoritys specification, an autonomous early warning system for forest fires must meet the following technical requirements:

Automatically recognize smoke formation of 10 m expansion by daylight within a radius of 10 km and within 10 minutes after becoming visible

High reliability in respect of fire recognition

Acceptable rate of false alarm

Localize the source of the fire

Easy maintenance

Autonomous transmission of smoke data to a control center

Full record-keeping of all events

Data transmission to control center must enable the operator to independently evaluate the potential hazard

System concept

Principally, there are various methods suitable to recognize vegetation fires, e.g. analyzing picture information provided by digital cameras or by infrared imagers, or detecting emission lines of conflagration gases, or active measurements with Lidar evaluating the laser signal backscattered from smoke particles. To find out which method is suited best, several preliminary tests were performed observing controlled fires with various sensors (CCD-camera, IR-radiometer, IR-spectrometer). We had to take into account our own results as well as experience gained internationally on the field of early forest fire recognition, also given facts on site in Germany, the technical requirements mentioned above and the required user-friendliness and economic efficiency. Bearing all this in mind, we chose a sensor type based on a digital CCD-camera with high resolution. Smoke detection within the visible spectral region is especially important in densely wooded forests, as open flames (which IR-sensors respond to) give alarm too late. Furthermore, cameras provide the operator in the control center with expressive images and hence make it easier for him to evaluate the situation. It was one of the projects main objectives to allow human contribution in a suitable way during the process of evaluating the alarm and selecting the appropriate fire fighting method. For such purpose, the control center is equipped with a number of computer-assisted supports.

Fig.1. Digital CCD-camera

The digital high resolution Frame Transfer CCD-camera with special filter (see Figure 1) scans the forests from the top of the observation tower. AWFS can also be mounted to braced poles of mobile phone providers, high buildings or other suitable locations. The images are resolved with 14 bits and transmitted via optical fibers to the computer unit which is located in the tower too. There they get analyzed by means of specially developed software. If there seems to be a smoke formation, compressed pictures and further details (time, position) are reported via ISDN to the control center, where they are processed in a PC displayed on the screen. The operator receives all information he needs to make decisions. Currently, one control center can support up to 7 towers. In each tower up to 8000 digital images with a data volume of 16 GByte are produced and evaluated every day.

Hardware components installed in the observation tower

The basic components of AWFS are shown in Fig.2. The most distinctive feature of the CCD-camera is its innovative electronic concept of four functional groups: CCD-head, clock-driver, analogue signal chain and controller. The camera is mounted on the very top of the tower by means of a pan and tilt unit (PTU). It takes the camera approximately 10 minutes to come full circle. The controller generates or manages all digital control signals for the CCD transport cycles, analog signal processing and PC-interface. Incoming commands are interpreted and carried out. The video signal is pre-processed in the signal chain on analog basis, then submitted to correlated double sampling, before it runs through further conditioning and multi-level filter. After the signal is digitalized in a 14bit analog-to-digital converter the image data are serialized and transmitted to the controlling PC via optical fibers.

Fig.2.Basic components of AWFS

The electronic components are utmost resistant against environmental conditions, stand out for their low energy consumption and extremely low noise. Due to the high radiometric resolution (~16,000 different grey scale values) the camera covers a wide range. Even very structures can be resolved under all sorts of lighting conditions. The 70 mm objective with 10° field of view allows 2 m geometric resolution in 10 km distance. Tests confirmed that the red-free filter increases the contrast between vegetation and smoke, as red light is hardly reflected at all by chlorophyll.

The pan and tilt unit can be positioned with a relative precision of up to 0.2° and with an absolute precision of 1° after being oriented in the landscape by means of GPS-defined land marks. During scanning stage three single images are taken in 1-second intervals for every camera position. Then, full image information is transmitted to a controlling PC at the tower bottom, where the data are evaluated, stored and passed on to an image processing computer. Both computers work with the operating system MS Windows NT.

Moreover, the controlling PC covers the following functions:

Autonomous control of camera image taking

Autonomous control of the pan and tilt unit

Compressing alarm images before transmitting them

Control of alarm data transmission (time, location of smoke etc.) to the operator in the control center

Autonomous transmission of sensor unit operating data to the operator (e.g. failure alarm)

Data transmission to the PC in the control center is currently achieved by a wired ISDN-connection. However, it is also possible do use radio transmission or other specific networks.

Image processing software

The image processing computer uses complex algorithms to identify smoke in real time. Simultaneously, it calculates the optimum exposure time and sends it to the controlling PC. The image processing software is the heart of the AWFS. It evaluates in only a few seconds typical features like dynamic and stochastic behaviour. In every camera position several images are taken. First of all, exact matching must be achieved for the images taken from the same camera position, because the towers tend to swing considerably in the wind. Next, the horizon line is determined in the image for orientation purposes. The smoke is identified then by means of dynamic and structural features and by its grey scale value. It is prerequisite to reliable recognition that several features are taken into consideration.

In a first step, typical features of smoke are looked for by analyzing a standard difference image. Wind and thermal convection of hot smoke gases change the grey scale value of smoke areas in the subsequent images. However, other environmental phenomena (e.g. clouds, wind, dust formations, reflections, bird flights, cars) can cause similar effects for short periods of time (in comparison with the time scale of the dynamic behaviour of smoke). Moving objects (cars, planes, birds) can be eliminated by an additional evaluation of the third image, because smoke is quite stationary within the time between first and last image (several seconds). Irrelevant space frequencies are eliminated by band-pass filtering the standard difference image. As the special red filter reduces the green colour of the forest significantly, smoke of wood fire always stands out against the surrounding forest. This fact supports additional suppression of interfering signals (as an example, smoke is easy to distinct from cloud shadow therefore. Finally, adaptable threshold values prompt the decision, whether fire alarm is to be released or not.

In a second step, the texture is evaluated. The respective method is based on the structural analysis of the texture of smoke, which can be clearly discerned from the surrounding structures. It works even without any comparison image and hence does not react to changes in illumination nor to moving objects like vehicles. From mathematical view, the structures are described as stochastic effects superimposed to the average grey scale value. Therefore, it is first necessary to calculate the estimated average grey scale value, so that the stochastic arises from the difference between the original and the estimated image. The mathematical basis is explained by Hetzheim (1999). Typical smoke structures are separated then by means of various procedures. A second image, which is prerequisite to the first step described above, are reused to verify the results.

In accordance with the observed features both methods proceed classing the identified possible smoke areas with probabilities. These are condensed to one total probability then. As an example, the total probability is low, if the identified areas do not overlap and clearly differ in size.

Each of the two methods described above works sufficiently enough to detect smoke on its own, but their simultaneous employment increases the reliability of smoke detection considerably.

Control Center

The control center, too, is equipped with a PC and appropriate software. It deals with the following tasks:

Control of several camera locations

Receive alarm images and data

Visualize alarm images in a suitable way and in correlation with digital maps

Display a low resolution panorama view of all towers administrated by the center

Manual area definition in order to permanently mask smoke of irrelevant origin (chimneys, villages, etc.)

Provide the operator with tools for adequate evaluation of images (zoom, image sequences, filters, facilities to change contrast and brightness)

Display the bearing lines of alarm messages on digital maps

Fade-in additional information and data bases in accordance with the users requirements

Fig.3. Fire detection from Kathlow tower on 8 August 1999

By means of the software developed for the control center, even operators who might not be familiar with modern PC-technology can easily make themselves acquainted with their scope of duties within a few days. Their knowledge about local conditions as well as the information the system provides them with enable them to soon make qualified decisions on initiation of fire fighting activities. Annex 2 shows a possible display variant on the monitor.

Results and discussion

Only practical operation can demonstrate the performance of an autonomous early-warning system for forest fires. Therefore, a pilot test was started during the forest fire season 1999, after several tests with controlled fire were made. Supplementary to traditional fire watching methods, AWFS were installed on three observation towers (Kathlow, Reuthen, Jerischke) of the Spree-Neiße district in southern Brandenburg, which is a region with very high forest fire risk. The numerous open pits and power plants in this region with their dust and smoke emissions make the task of fire watching especially difficult. The control center is located at the premises of the local forest authority in Peitz. The test results were monthly evaluated and reported in cooperation with the responsible officers.

In the test region 16 forest and field fires happened. All these fires were detected and indicated by the AWFS within the set time limit. Despite the approximately 10 min time of revolution, fire indication sometimes (especially during late afternoon) was given even earlier than by the experienced observation tower staff, who obviously suffered from symptoms of tiredness. Figure 3 is an example of automatic smoke detection.

False alarms mean a specific problem. One differentiates between alarm due to irrelevant smoke sources, e.g. chimneys, and proper false alarm. Irrelevant smoke sources are usually stationary objects. Therefore, a facility was created, that allows the operator to permanently mask these sources. The complex image analysis during which various features are evaluated in a multi-step process has been described above and proven to efficiently avoid potential false alarms.

Figure 4 presents the statistical evaluation of the false alarm rates at all three pilot project locations during the period from 16/8/1999 to 18/9/1999 (end of forest fire season). For most days the rate of false alarm is clearly less than 1%. About 230 decisions about smoke formations are to be made hourly by the software on each tower. A rate of 1 % means approximately 2 false alarms per hour, which the operator can easily cope with. However, under certain weather conditions the number of false alarms increases due to light reflection, ascending water vapor (after short but heavy rain) or low clouds. Dust formation as a result of harvest activities can be taken for smoke, too. Even experienced staff has often considerable problems to differentiate properly though. The region around Kathlow has higher rates, which is due to Cottbus city and the Jänschwalde open pit and power plant being in the range of view of the camera. The option to mask such smoke sources was not entirely used yet in the pilot project.

Fig.4. Number of days with different rates of false alarm at the different AWFS locations from 16 August to 18 September 1999

Any problems occurring were continuously evaluated during the test stage and the software improved accordingly. As a result, the user was satisfied with the AWFS.

All in all, AWFS offers the following advantages:

Reliable and flexible observation of regions with high forest fire risk, prepared for service at any time of the day

Omission of jobs with difficult working conditions, creation of new jobs in equipment production and maintenance as well as in the control center

No need for observation towers in forest regions, low costs for installation and maintenance (braced poles of mobile phone providers)

Further development

The test-stage turned out to be successful. The experience gained will be considered and evaluated during the next few months. A new generation of AWFS will be developed and tested.

Here are the focal points of future development:

The computers of several towers will be concluded in a direct network, so they will be able to control the operation of each other (watchdog-system) and hence further increase reliability in service

High performance PCs will be used, which will lead to lower turn-around times

False alarm rates will be still reduced by further development and optimization of the software, making use of the comprehensive image data base

Reliability of smoke detection will be further improved by means of a neuronal algorithms for classification

Due to its universal basic structure, AWFS can be used in other areas as well. The concept of the system (digital camera with high spatial and radiometric resolution, wide range in brightness, real-time image processing, autonomous alarm signal transmission to a control center) and the experience gained so far in detecting complex structures in natural environment are suitable for various observation tasks, e.g. environmental monitoring or security duties. The system can not only observe sensitive areas, but also autonomously give alarm, transfer data to any other place and selectively store images.

References

Breejen, E. den, Breuers, M., Cremer, F., Kemp, R.A.W., Roos, M., Schutte, K., and Vries, J.S. 1998. Autonomous Forest Fire Detection. In: Viegas, D.X. (Ed.), Proceedings of the III International Conference on Forest Fire Research and 14th Conference on Fire and Forest Meteorology held in Luso, Coimbra, Portugal on 16-20 November 1998, pp. 2003-2012.

Briess, K., Bärwald, W., Gerlich, T., Jahn, H., Lura, F., and Studemund, H. 1999. The DLR Small Satellite Mission BIRD. Proc. of 2nd IAA Symposium on small satellites for Earth observation, Berlin, April 12 – 16, p. 45-48

Gonzalo, J. 1996. FUEGO programme. Proc. IAA Symp. on Small Sat. for E. O., Berlin 1996, IAA-B-902.

Hetzheim, H. 1999. Analysis of Hidden Stochastic Properties in Images or Curves by Fuzzy Measures and Functions and their Fusion By Fuzzy-or Choqut Integrals. Proc. , 5th International Conference on Information Systems Analysis and Synthesis, Orlando, Florida, pp. 501-508.

E. Kührt, T. Behnke, H. Jahn, H. Hetzheim,
J. Knollenberg, V. Mertens, G. Schlotzhauer
Deutsches Zentrum für Luft- und Raumfahrt
Rutherfordstr. 2
D-12489 Berlin
GERMANY

and

B. Götze
INO control GmbH
Schulstr. 6
D-01728 Possendorf
GERMANY

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Country Notes
IFFN No. 22

24. November 2017/by GFMCadmin

Germany: Fire Situation (IFFN No. 24)

de
Fire Situation in Germany

(IFFN No. 24 – April 2001, p. 22-30)

Introduction

In Germany the main fire problem areas are located in the northern portion of the country where predominantly poor soils are associated with continental climate features. The forests in this region between Lower Saxony in the West and Brandenburg in the East (bordering Poland) are dominated by pine (Pinus sylvestris) stands characterised by a relatively high fire hazard.

The Statistical Database on Forest Fires

In 1991, the first uniform forest fire statistics were introduced in the Federal Republic of Germany. Between the end of the Second World War and the unification of the two separate German republics each system operated its own statistical database (Figure 1 a). The compilation of forest fire statistics of the former German Democratic Republic (GDR East Germany) started in 1946. Data for the Federal Republic of Germany (West Germany) were not available before 1957. With the reunification in October 1990, a common fire statistics system was introduced in Germany that met the standards of the ECE/FAO.

Figure 1 a. Average number of forest fires and area burned in Germany in 5- and 10-year periods, 1946-1999.

The majority of fire damages occurred after the war in the East German territory. Although the number of fires was sometimes smaller than in West Germany, the burned area, except from 1971 to 1980, was larger than in West Germany (Figure 1 b). Between 1951 and 1960 the highest post-war fire damage occurred in the GDR (Figure 1 c). In this period the average number of 1 761 fires per year was registered with an average burned area of 3 660 hectares per year. In this context, it is important to note that forest land comprises only 28 percent of East Germany.

Figure 1 b. Number of forest fires in Germany, 1946-1999.

Figure 1 c. Area burned in Germany, 1946-1999.

In 1990, the real causes of fires in the GDR were published for the first time (Missbach 1990). For political reasons the issue was treated secretly. During the period 1951 to 1970 fires caused by negligence mounted 46 percent and, in the subsequent years, up to 60 percent. Railway traffic caused 28 percent of the ignitions by sparks from locomotives which were driven with brown coal. During the period from 1971 to 1988 the percentage of fires caused by military training and exercises increased to 29 percent. These fires were located outside the borders of the military exercise areas; they had been hidden in the statistics before 1990.

In West Germany, the conflagrations of the years 1975 and 1976 in Lower Saxony had a strong impact on the statistics for the period 1971 to 1980. The average number of fires rose to 2 107 with an average burned area of 2 884 ha per year. In 1975 the average size of the burned area per fire increased to 5.15 ha. The number of fires and the area burned depend on inter-annual climate variability and ranged from 242 ha in the wet year 1985 to a maximum of 8 768 ha in the hot and dry year 1975. Therefore, the West German statistical figures show that the burned area of 1975 was 36 times larger than in 1985. The importance of the climate is also represented in the average size of the burned area. In East Germany the amounts ranged from 0.52 up to 6.93 ha between 1946 and 1990; whereas West German data show areas from 0.35 to 5.15 ha (Figure 2 a).

The average burned area per fire in the period 1977 to 1999 is shown in Figure 2 b. After reunification 1992 shows a peak of burned area with 4 908 ha (Figure 3). More than 80 percent of these fires happened in East Germany and a considerable number started on military training areas. This phenomenon can be explained by the political circumstances. In the former GDR the fire brigades were managed by fire bosses who were members of the police force. As a result of the reunification they had quit their jobs. The democratically elected new fire bosses lacked the experience in fighting large forest fires. The inadequate technical equipment of the rural voluntary fire brigades worsened the situation.

Figure 2 a. Average size per forest fire in Germany, 1946-1999.

Figure 2 b. Average size per forest fire in Germany, 1977-1999.

Figure 3. Number of forest fires and area burned in Germany,1977-1999.

Fire causes

Only two percent of all fires are caused by lightning. The identification of fire causes is unsatisfactory because the average percentage of unknown causes is 39 percent from 1991 to 1999 (Figure 4 a, b). Negligence holds second place with 25 percent in the period 19911999. Negligence had a higher percentage in West Germany, decreasing from 50 percent to 30 percent between 1961 to 1990. There is a steady increase of arson in West Germany since 1961, with an average percentage of 22 percent in the period 19911999 in the whole of reunified Germany. The reduction of military training and the electrification of railways, especially in East Germany, explain the decrease of the “other causes” to ten percent. The four most important “other causes” are the railway, public ways, agriculture and forestry. Figures 5 a and 5 b show the monthly distribution of fires between 1995 and 1999 in Germany. The average number and the average burned area in this period indicates two peaks in April and August. This supports the earlier theses of Geiger (1948), Weck (1950), and Missbach (1982) that most fires occur in spring and in high summer.

Figure 4a. Causes of fire in relation the number of fires in Germany, 1977-1999

Figure 4b. Causes of fire in relation the area burned in Germany,1977-1999.

Figure 5a. Distribution of number of fires by month in Germany,1995-1999.

Figure 5b. Distribution of area burned by month in Germany,1995-1999.

Prescribed burning

Since forest fire management in Germany is not faced with exceptional fire problems, the use of prescribed fire in forest stands for wildfire hazard reduction has not been seriously considered. Prescribed fire has been proposed and tested in pilot experiments during the 1970’s (Goldammer 1979).

However, changing paradigms regarding the role of fire in nature conservation have been observed the past few years. At present new initiatives are demanding the restoration of fire as a dynamic and vital element to maintain biodiversity and the cultural and ecological characteristics of landscapes. Changes in many vegetation types have occurred as a consequence of abandoned traditional land-use practices. Ecologically important disturbances by land-use practices include grazing, mowing, bio-fuel utilization and burning. Traditionally fire was used to keep vegetation open and at early successional stages to regenerate grass, heath and brush, and to clear land of weeds and harvest residues. Since 1975, a vegetation burning ban has been imposed in all German states.

Targets of these initiatives are those ecosystems and landscapes that had been treated with fire historically and where prescribed fire could be used to prevent the reforestation process.

In 1997, the first large prescribed burning research programme began in the State of Baden-Württemberg. It aims to investigate the use of prescribed burning in the management of hedge and slope terrain in the viticulture region of Southwest Germany. The objective of this programme is to use fire to maintain or restore grass cover that provides habitats for endangered flora and fauna. The project was requested by the State Ministry for Rural Space of Baden-Württemberg because of the dramatically increasing subsidies necessary to mow and mulch those sites where biodiversity is lost due to succession towards bush and forest cover (Page and Goldammer.2000). Detailed references on the historic role of fire in European land-use systems and strategic concepts on the use of fire in modern nature conservation and landscape management are provided by Goldammer et al. (1997 a, b, c).

Fire research

Fire science in Germany has a traditional focus on fire ecology, fire management and fire policies at Freiburg University. The Fire Ecology Research Group (FREG) concentrated its efforts on the tropics and the boreal zone, and on the role of fire in the global environment. In 1990, the FREG was integrated into the Max Planck Institute for Chemistry. Since then the institute conducts interdisciplinary fire research in support of biogeochemistry and atmospheric chemistry studies. Since 1998, the FREG has hosted the Global Fire Monitoring Center (GFMC 2000).

Advanced sensor technologies and operational systems of dedicated fire satellites are required to improve the spatial-temporal coverage and information content for research and disaster management purposes. A prototype improved high temperature event (HTE) sensor, the Bi-spectral IR Detection (BIRD) small satellite mission, is being developed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt – DLR) in cooperation with the GFMC. A launch date has been set for June 2001. The development of the Innovative Infrared Sensor System FOCUS, to be flown as an early external payload of the International Space Station (ISS), is another project developed by DLR (Oertel et al. 2000).

The DLR has also developed the Autonomous Early Warning System for Forest Fires in Brandenburg State (Kührt et al. 2000).

A German Research Network for Natural Disasters was established in 1999. The Forest Fire Cluster is focusing on the development of an operational fire modeling, information and decision-support system for the State of Brandenburg (DFNK 2001).

The German fire science community is actively involved in the work of the German Committee on Disaster Reduction (within the ISDR) and its Scientific and Operational Advisory Boards (http://www.dkkv.org).

During the 1990’s, the research conducted under the scientific framework of the Biomass Burning Experiment (BIBEX) of the International Geosphere-Biosphere Programme (IGBP), International Global Atmospheric Chemistry (IGAC) Project and an increasing number of other projects has provided a sound base for understanding the implications of wildland fires on ecosystems, planetary-scale processes (biogeochemistry, atmospheric chemistry, climatology) and humanity. Some elements of the international fire research programmes have been initiated, planned and implemented by German research institutions (BIBEX 2000).

A number of fire management projects or fire management project components within forestry development projects have been implemented or are underway at the international level. Most advanced are Integrated [Forest] Fire Management (I[F]FM), or Community-Based Fire Management projects. The projects were supported by the German Ministry for Economic Cooperation (GTZ 2001) (See also Asia regional report and country reports for Indonesia and Mongolia).

References

BIBEX 2000. The Biomass Burning Experiment (BIBEX) of the International Geosphere-Biosphere Programme (IGBP), International Global Atmospheric Chemistry (IGAC): https://gfmc.online/bibex/Welcome.html
Bundesministerium für Ernährung, Landwirtschaft und Forsten. Waldbrandstatistik der Bundesrepublik Deutschland”, Bonn. Annual reports (until 1993).
Bundesanstalt für Landwirtschaft und Ernährung. Waldbrandstatistik der Bundesrepublik Deutschland”, Frankfurt/M. Annual reports (since 1994).
DFNK 2001. Deutsches Forschungsnetz Naturkatastrophen (German Research Network for Natural Disasters): http://dfnk.gfz-potsdam.de.
Geiger, R. 1948. Neue Unterlagen für eine Waldbrandbekämpfung 2.Teil. Witterungsbedingungen für Großwaldbrände. Mitteilungen des Reichsinstitutes für Forst- und Holzwirtschaft Nr. 5.
GFMC 2000. Global Fire Monitoring Center: http://www.uni-freiburg.de/fireglobe/
Goldammer, J. G. 1979. Der Einsatz von kontrolliertem Feuer im Forstschutz. Allg. Forst- u. J. Ztg. 150, 41-44.
Goldammer, J.G., J. Prüter, and H. Page. 1997a. Feuereinsatz im Naturschutz in Mitteleuropa. Ein Positionspapier. Alfred Toepfer Akademie für Naturschutz, Schneverdingen, NNA-Berichte 10 (5), 2-17.
Goldammer, J. G., S. Montag, and H. Page. 1997b. Nutzung des Feuers in mittel- und nordeuropäischen Landschaften. Geschichte, Methoden, Probleme, Perspektiven. Alfred Toepfer Akademie für Naturschutz, Schneverdingen, NNA-Berichte 10 (5), 18-38.
Goldammer, J.G., and H. Page. 1997c. Bibliographie: Feuerökologie in Mitteleuropa – Perspektiven. Alfred Toepfer Akademie für Naturschutz, Schneverdingen, NNA-Berichte 10 (5), 175-181.
GTZ 2001. GTZ Special. A summary of fire management projects conducted by the German Agency for Technical Cooperation (Deutsche Gesellschaft für Technische Zusammenarbeit). Special issue, International Forest Fire News No. 23 (in press).
Kührt, E., T. Behnke, H. Jahn, H. Hetzheim, J. Knollenberg, V. Mertens, and G. Schlotzhauer. 2000. Autonomous Early Warning System for Forest Fires tested in Brandenburg. International Forest Fire News No. 22, 84-90.
Kuratorium für Waldarbeit und Forsttechnik. 1976. Waldbrand, Vorbeugung und Bekämpfung”, Mitteilungen des KWF Band XVII, Buchschlag.
Lex, P. 1996. Bekämpfung von Waldbränden, Moorbränden, Heidebränden. 4. Auflage, Verlag W. Kohlhammer.
Missbach, K. 1982. Waldbrand, Verhütung und Bekämpfung”. VEB Deutscher Landwirtschaftsverlag, Berlin, 3. Auflage.
Missbach, K. 1990. Zur Auswertung der Waldbrandstatistik der DDR. Forstwirtschaft Berlin 40, 3
Oertel, D., P.Haschberger, V.Tank, F.Schreier, B.Schimpf, B.Zhukov, K.Briess, H.-P-Röser, E.Lorenz, W.Skrbek, J.G.Goldammer, C.Tobehn, A.Ginati, and U.Christmann. 2000. Two dedicated spaceborne fire missions. In: Proc. Joint Fire Science Conference and Workshop, Boise, Idaho, USA, 15-17 June 1999, Vol.I, p. 254-261. Published by the University of Idaho and the International Association of Wildland Fire.
Page, H., and J. G. Goldammer.2000. Fire history of Central Europe: Implications for prescribed burning in landscape management and nature conservation. Paper presented at the Baltic Exercise for Fire Information and Resources Exchange (BALTEX FIRE 2000), Kuopio, Finland, June 2000 (in press).
Weck, J. 1950. Waldbrand, seine Vorbeugung und Bekämpfung. Brandschutz-Fachbuchreihe 19, W. Kohlhammer Verlag.

Contact addresses:

Peter Lex
Kirchweg 2 A
D-21365 Adendorf
Germany

and

Johann G. Goldammer
Editor, IFFN
Global Fire Monitoring Center (GFMC)
Freiburg, Germany

[

| IFFNNo. 24 | Specials | Country Notes ]

24. November 2017/by GFMCadmin

Germany: Reorganization of Wildland Fire Research: Linking Wildland Fire Science with Biogeochemistry and Atmospheric Sciences (IFFN No. 4 – December 1990)

de

Reorganization of Wildland Fire Research:
Linking Wildland Fire Science with Biogeochemistry and Atmospheric Sciences

(IFFN No. 4 – December 1990, p. 4)

The Fire Ecology Research Unit at the Institute of Forest Zoology, Department of Forestry, at the University of Freiburg, has now been reorganized. This research branch had been supported by the University of Freiburg and the Volkswagen Foundation for more than 10 years. Besides its function as an academic institution, the unit had carried out a series of fire research and management projects around the globe. Main research emphasis was the exploration and definition of wildland fire ecology and management in the tropics of South America and Southern Asia, but also in northern Asia. The unit was the organizer of the International Symposia on Fire Ecology at the University of Freiburg between 1978 and 1989 (see under Recent Publications) and also served as editing office of this International Forest Fire News.

Although its offices remain at the same place at the University of Freiburg, the unit is now reorganized as “Fire Ecology and Biomass Burning Research Group”, a subdivision of the Max-Planck Institute of Chemistry, Biogeochemistry Department (Mainz). The aim of this marriage between terrestrial fire research and atmospheric sciences is to link both disciplines in order to understand better the global issues on wildland fires.

The correspondence address is the same as before.

Johann Georg Goldammer (Editor IFFN)
Fire Ecology and Biomass Burning Research Group

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24. November 2017/by GFMCadmin

Germany: The Mount Athos Conflagration (Greece) of 1990: Aerial Fire Fighting Support with German Helicopters (IFFN No. 4 – December 1990)

de

The Mount Athos Conflagration (Greece) of 1990:
Aerial Fire Fighting Support with German Helicopters

(IFFN No. 4 – December 1990, p. 4-6)

By end of August 1990 a disastrous wildfire struck the autonomous monastic district of Athos which occupies the easternmost prong of the Chalcidice peninsula (Northeast Greece). For more than one week the monks, forest workers, fire brigades and the miltary tried to suppress the fire. Due to the extended drought conditions and the difficult terrain it was a hopeless effort. Since the CANADAIR scooping airplanes were not able to join the fire battle continuously, mainly because of rough sea state and steepness of terrain, the Government of Greece asked the Federal Republic of Germany for aerial forest fire suppression support.

This request was made in the morning of 24 August. On the next day a German C 160 Transall miltary transport plane took off for Greece. The plane was boarded by the aerial fire fighting coordinator and four helibuckets (capacity 5,000 l). The first two CH 53 G helicopters followed soon. On the way to Greece the helicopters had to fly over Austria and via Yugoslavia and arrived at Thessaloniki in the evening of 26 August. On 27 August, in coordination with the scooping planes, the first helicopter-borne fire suppression tasks started. Three additional CH 53 G, the heaviest helicopter available in the German Armed Forces, arrived on the scene on 28 August. They became available at the moment when the scooping planes were not able to operate anymore due to the adverse weather conditions.

The aerial fire suppression was successfully terminated in the evening of 30 August. However, the helicopters were available on stand-by until 1 September. Alltogether the German military personnel (totaling 45 persons) was able to fly 344 fire suppression tasks (45 flying hours) and delivered 1.72 million liters of water on the fire scene.

Fig.1. German Armed Forces CH-53G in joint fire fighting operations with the Greek Armed Forces Bell UHD helicopters. Photo: Courtesy LtCol K.Zernia

The Mount Athos fire has destroyed very valuable pristine forest resources. And a recent report from the site revealed that severe erosion has occurred, even leading to the formation of a new sand bank along the shore. However, things could have been much worse if the fire fighting capabilities had not been enforced by the helicopters requested from Germany. There are many lessons to learn from that fire. One lesson is that a difficult terrain such as on Mount Athos requires a variety of fire extinguishing means among which the helicopters are very efficient, especially in situation in which fixed wing fire planes and scoopers are not operational any longer.

Another lesson is that such international efforts in fire disaster control may become mandatory in order to protect the common heritage of our natural and cultural resources. However, in order to be prepared better for unforeseen events, such as the Mount Athos fire, bilateral and multinational agreements could ensure that European forest fire fighting capabilties could be used in a more efficient way.

Lt.Col.Klaus Zernia

Aerial Coordination Officer
of the German Helicopter Group at the Mount Athos Fire
Fliegende Abteilung 151
Schüttdorfer Damm 1 e
D-4400 Rheine
Germany

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24. November 2017/by GFMCadmin

Germany: Long-term Fire Statistcs Update (IFFN No. 7 – August 1992)

de

Long-term Fire Statistcs Update

(IFFN No. 7 – August 1992, p. 17,21)

This is the first time the German Federal Ministry of Food, Agriculture and Forestry has published forest fire statistics for the unified territory of Germany. Until the unification in 1990 the Federal Republic of Germany and the German Democratic Republic kept separate fire records (see IFFN No.2, December 1989). This explains the sudden increase in the total number of fires and forested area affected by fires by 84% and 91% respectively (Tab.1).

Tab.1. Forest fires in Germany from 1977 to 1991: Fire causes, number of fires, burned area and estimated damage. The fire statistics of the former German Democratic Republic are first included in 1991. Source: Bundesministerium für Ernährung, Landwirtschaft und Forsten 1992

Year

Negligence

Arson

Lightning

Other Causes

Unknown Causes

Total

Damage (estimated)

No.

ha

No.

ha

No.

ha

No.

ha

No.

ha

No.

ha

Mio. DM

DM/ha burned area

1977

384

151

172

80

2

0

248

215

294

167

1100

613

2.5

4078

1978

212

76

94

32

8

0

157

103

163

78

634

289

1.2

4152

1979

219

79

75

34

2

0

203

154

201

89

700

356

1.2

3371

1980

471

368

132

57

4

1

375

886

388

233

1370

1545

3.8

2450

1981

255

143

125

33

1

0

79

207

184

114

644

497

2.5

5030

1982

441

164

223

138

3

1

198

327

379

121

1244

751

3.7

4927

1983

296

150

197

92

22

1

227

256

367

293

1109

792

6.7

8460

1984

460

264

183

105

2

0

148

303

370

203

1163

875

5.1

5829

1985

163

67

146

47

2

0

72

86

139

42

522

242

1.3

5372

1986

151

48

146

36

5

1

121

152

195

56

618

293

1.4

4778

1987

168

136

99

41

2

0

105

96

110

46

484

319

1.6

5016

1988

164

48

143

21

6

0

104

86

142

127

559

282

1.4

4965

1989

192

39

237

64

12

1

135

117

230

60

806

281

1.8

6406

1990

311

131

225

86

28

6

152

146

285

113

1001

481

10.5

21830

1991

395

245

460

127

11

4

333

309

647

236

1846

920

3.3

3587

Changes from 1990 to 1991 (%):

+27

+87

+104

+48

-61

-33

+119

+112

+127

+109

+84

+91

-69

-84

From: Federal Ministry of Food, Agriculture and Forestry
Address:
P.O.Box 14 02 70
D-W-5300 Bonn 1

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Country Notes

24. November 2017/by GFMCadmin

Germany: Environmental History: European Regional Smog from Peat-Swamp Burning in Germany (IFFN No. 18 – January 1998)

de

Environmental History:
European Regional Smog from Peat-Swamp Burning in Germany

(IFFN No. 18 – January 1998, p. 59-60)

Historic Moor Cultivation

In the 18th century the landscape of Northern Germany was dominated by large uncultivated bogs and swamps. In 1770 about 1/7 of the total area of Niedersachsen was uncultivated bogs. The common people were afraid of these ‘dark and wild’ places and tried to stay away from these areas, which were perceived to be haunted. But with the population growth of the end of the 18th century, people were forced to enlarge the area under production and started to cultivate these areas. To fulfil their plans they began to burn the bogs.

Burning Methods

The chosen plots for the new settlement must first be drained and levelled of. This work was done in autumn with the establishment of ditches which were laid out in such a way that the plot was divided into long narrow strips. The purpose of this work was to dry out the plot for further treatment. In spring of the following year, the upper organic layer of the bog was removed with big hoes, and the duff was cut out in quadratic clods. If the year was very wet this work was done in early autumn. In these wet years the ground had to be broken up several times.

In May work requiring strong men began: the clods had to be thrown and stacked into little piles. Thereafter these piles of stacked and dried clods were ignited. As soon as the material was half-burned, the still burning pieces were distributed against the wind all over the field. The fire had to burn for several days at calm weather for several days. It was very important that the fire be watched over so that it did not penetrate the deeper organic layers. The bog area only had to burn slightly or, in other words, smoulder. This work was extremely strenuous and the workers’ clothes were covered with ash and dust, while their eyes were constantly a shade of red during the burns.

The burning of the bog began mainly in mid-May and ended in June. The drying of the organic material and the heat caused the normally barely accessible plant nutrients of the bog to break up enabling the cultivation of oat and buckwheat on the freshly burned fields, without fertilization.

The burning of the bogs was however not possible on the same plot year after year, over a longer period of time. In general a single plot was burned and tilled over a period of six to seven years. After the cultivation period a fallow period of 20 years was necessary. For this reason shifting cultivation was practised, where thereafter a neighbouring plot was used for the next 6 to 7 years, after which new land was then cultivated.

The burning of bogs was first noted in the year 1583. At that time the regional administrator (Drost) of the Emsland enacted a strict ordinance against this kind of “cultivation”.

In 1669 similar ordinances existed in the counties of Oldenburg and Delmenhorst. In 1720 the following was written: “In the Emsland the farmers are not willing to desist burning the bogs. They rather would pay the fine and continue to burn.”

The first stimulus for the agricultural use of the moor came from the Netherlands. The upper organic layer of the moor was used for peat production and afterwards the dismantled moor was cultivated (“Fehn” cultivation).

Burning practices were introduced as well from the Netherlands to Eastern Friesland and spread from there throughout northwest German bog areas.

The “Dry Fog”

The burning of the bogs had an oppressive effect on the northwest German areas, even in areas far away. This effect, the “smell of burning” was known under the term “High Smoke”. What is “High Smoke”? Why was the smoke of the bogs called “High Smoke”?

The bog researcher Racke wrote: “The dark, thick and heavy, evil-smelling smoke covered the land for miles. In the spring often in the shape of a high dark wall, it rapidly gathers like a storm-cloud and covers the sun so that it looks like a dim disc. At more favourable conditions the smoke escapes, and the longer it travels the weaker it gets, ending as haze, carried into areas far away as Hungary or Southern France. In Germany this phenomenon is called “Heerauch”, “Haarrauch”, “Höhenrauch” and is hardly liked. Public opinion made it responsible for all sorts of damage. It is said that it drives away rain. The farmers of the “Alte Land” said that it damages the blossoms of fruit trees, and that it should even drive melancholical people to suicide.” For years the inhabitants of countries far away from the actual bog burns were puzzled over the origin of the recurring smoke. The French, for example, thought that the “brouillard sec” was dried fog. The English called the bogsmoke “dry fog”. The puzzlement did not stop:

In 1657 the bog burnings began on 6 May in Northern Friesland carried by strong easterly winds. Already on the next day the smoke had reached Utrecht, and a little bit later had changed direction, passing Leeuwarden towards Den Helder reaching the sea on 15 May. There, the wind changed suddenly northwest and drove the bog smoke back, so that on 16 May it had reached Utrecht and Nijmwegen again. At the same time the smoke was also noticed in Hannover, Münster, Köln, Bonn, and Frankfurt. On 17 May the smoke reached Vienna, on the 18th May Dresden and Krakau on 19 May.

Johann G. Goldammer (Editor IFFN)

Fig. 1 Moor burning in Friesland around the turn of the century. Smoke from these land-use fires sometimes covered large areas of Europe.

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24. November 2017/by GFMCadmin

Germany: Fire in Nature Conservation and Management: Changing Paradigms? (IFFN No. 18 – January 1998)

de

Fire in Nature Conservation andManagement:
Changing Paradigms?

(IFFN No. 18 – January 1998, 69-72)

While no substantial changes in the field of forest fire management can be reported from Germany (see forest fire statistics update in Table 1), some recent developments in nature conservation are shaking the foundations of German landscape management. Interestingly enough, this is happening at the time of the publication of Stephen J. Pyne’s comprehensive analysis of the cultural history of European fire “Vestal Fire” in which he states:

“Europe’s peculiar geography and dense demographics, and the intensity of its agricultural reclamation, gave European fire a special character. Europe’s temperate core – not shaped by well-defined fire season – granted humans an unusual degree of control over fire, and encouraged the belief that fire was, in principle, a strictly human agency, that it was a convenient tool but not an essential process. If fire’s importance was instrumental and ceremonial, it could be replaced by less volatile technologies and more modern rites, much as wheat replaced weedy brome and draft oxen replaced wild aurochs. Fire was, so the saying went, a good servant but a bad master.”

“The keepers of Europe’s flame accepted this condition as normative. They distrusted free-burning fire and sought to cultivate it from landscape and ultimately replace it with the industrial combustion of fossil fuels. Europe came itself to resemble a fire in which a burned-out core smoldered, aglow with random embers, while flames propagated along its perimeter, not only the margins of western Eurasia but the colonial periphery to which Europe carried the torch. The geography and dynamics of fire on the contemporary Earth is largely a consequence of European expansion, the impact of an imperial Europe and an industrial Europe. Europe’s fire became as much a standard of reference for fire practices as Greenwich mean time for the world’s watches or SI units for global physics.”

“Germany is a controlled landscape. It has to be, given its population pressures. The German nature reserves constitute only 1.1 percent of the national landmass, with 200 of them less than 5 hectares in size, other restricted landscapes amount to 18 percent. None tolerate fire. Even outside theses zones, agricultural burning is rigorously proscribed to specific seasons. The burning of hedges, in particular, has aroused strong condemnation over the centuries because it breaks down the careful borders of political and propertied world, another illustration of fire as manifestation of social disorder. That perception describes perfectly the difference between landscape organized as a house instead of an ecosystem. Behind these fears lay the memory of the war’s fire catastrophe.”

His statements are right. In the very geographical centre of Europe – in Germany – the post-World War II development continued to perfectly eradicate some key factors which are vital elements of the cultural heritage of landscapes and biodiversity. The cultural landscapes and vegetation patterns of Central Europe are the result of hundreds of years of intensive utilization of the land. Cutting, mowing, grazing and burning were the methods used for harvesting timber and fuelwood, improving site conditions, growing domestic livestock by stimulating and regenerating desirable grasses, herbs and bushes, and by removing non-desirable, moribund and dead plant biomass. Like elsewhere in the world, our ancestors practised slash-and-burn methods which had a similar physiognomy all over Europe and followed principles similar to the swidden agricultural systems of the tropics.

In Germany, systems of rotating swidden agriculture were part of a forest utilization cycle, known as Reuteberge (Rüttibrennen), Birkenberg– and Haubergwirtschaft, which created a mosaic of forest, open grazing and agricultural lands, with all the successional stages in between. Within the Black Forest region (Southwest Germany) swidden agriculture was practised on ca. 70,000 ha by the middle of the 19th Century. After World War II – around 1950 – this system was still alive on ca. 10,000 ha.

Regular burning of juniper grasslands in South Germany and on heathlands (Calluna) in North Germany was quite common until the late 19th century. The intensive utilization of heathland by sheep grazing and the use of raw humus for stables and fuel supply resulted in the creation of nutrient-poor sites. These sites, however, provided ecological niches – habitats – for a variety of plant and animal species.

Ignoring the fact that Central Europe’s face has been shaped by traditional practices in agriculture, pastoralism and forestry over hundreds of years, nature conservationists and landscape planners attempted to preserve this heritage by excluding land-use methods. The creation of completely protected refugia for nature, embedded in a rapidly growing post-modern industrial society, was built on the vision that the preservation of nature and biodiversity could be reached only with the exclusion of all disturbances. This policy soon turned out to be a misconception. The heathlands of North Germany, rich in biodiversity and popularity, as mediated by the romantic writer Hermann Löns, began to change: With every hectare abandoned by sheep and shepherds’ fires the forest reconquered the terrain. Monotonous pine forests began to replace the flowering heathlands.

This misconception became visible at a large scale with the changing socio-economic conditions of post-war Europe and the increasing influence of European and global markets on the national agricultural sector. High production costs – as compared to the competitive international economies and markets – and incompatibility with the demands of a modern industrial society led to a dramatic decrease in the utilization of vegetative matter. While a similar process in the Mediterranean countries provided the fuels for more and more intensive wildland fires, afforestation of abandoned farm lands became a regular practice in rural Germany. Only a restrictive practice of issuing afforestation permits halted the tendency of steadily growing forest cover and the loss of variety in traditional landscape patterns. Abandoned sites which landscape architects wanted to keep open, e.g. for recreation reasons (hiking, skiing), had to be treated through subsidies by the government. Mowing, mulching and grazing in accordance with landscape plans, however, soon became prohibitively expensive.

Ironically, all this became most visible at the end of the Cold War. The reduction of military stationed on German territory set free a tremendous amount of military surplus. Large military exercise areas in former East and West Germany were abandoned and put under nature protection laws. With the retreat of the military exercise gunfire and manoeuvres the disturbances disappeared. Soon it was recognized that the impact of fire and heavy vehicles had been most important in continuously halting and creating new succession opportunities for a rich subclimax species variety. In other words: With increasing protection and the exclusion of disturbances, diversity began to decline.

Increasing costs for large-scale landscape gardening all over Germany, the dramatic challenges of vegetation utilization on former military areas, on marginal sites and steep terrain, on extremely small patches, e.g. hedge strips, between intensively used agricultural and viticultural sites – important refugia for species that could not survive in the chemo-technical environment of industrial agriculture, created new discussions about maintaining the cultural heritage.

Fig.1. Prescribed fire in the Kaiserstuhl viticulture area, Southwest Germany: First experiments in January 1998. Photo: Fire Ecology Research Group.

It was only about two years ago that ecologists and nature conservationists in Germany began to think about restoring the use of fire in those landscapes that had been treated with fire historically and which were threatened by the exclusion of all disturbance. Within 1996-97 a fire revolution swept over the offices of the public administrations and the media. While the public is concerned by seeing the threatening smoke come out of Southeast Asia and local farmers are still punished for the illegal use of fire, fire scientists began to sort out the pros and cons of restoring fire in maintaining biodiversity and landscape aesthetics. Within less than a year four scientific workshops were held at the State Academies for Nature Conservation in Lower Saxony, Hesse, and Baden-Württemberg, and finally, in August 1997, the Federal German Nature Conservation Academy held a workshop on “Restoration of Dynamic Processes in Nature Conservation”, in which fire played a key issue. In 1997 the first large prescribed burning research program began in the State of Baden-Württemberg, aiming to investigate the use of prescribed burning in the management of hedge and slope terrain in the viticulture region of Southwest Germany (Fig.1). The use of fire to maintain or restore grass cover, a habitat for endangered flora and fauna, is the objective of a program which is driven by the dramatically increasing costs for subsidized landscape gardening and the fact that many of the vulnerable sites have been lost to the succession towards bush and tree cover.

The changing paradigm in nature conservation in Germany is clearly visible. The signals emitted by nature conservation fires clearly show that the fire ban imposed on German landscapes in the mid-1970s cannot be kept any longer. The solutions, however, must consider the manifold sensitivities of an industrial society, in which a high awareness on environmental issues determines day-to-day politics.

Tab.1. Forest fire statistics of Germany 1977-96: Causes,number of fires, area burned, and economic damage.
Source: Federal German Ministry for Agriculture and Food.

Year

Arson

Neglicence

Other

Lightning

Unknown

Total

Damage

#

Area burned (ha)

#

Area burned (ha)

#

Area burned (ha)

#

Area burned (ha)

#

Area burned (ha)

#

Area burned (ha)

#

Area burned (ha)

1977 *

172

80

384

151

248

215

2

0

294

167

1100

613

2.5

4078

1978 *

94

32

212

76

157

103

8

0

163

78

634

289

1.2

4152

1979 *

75

34

219

79

203

154

2

0

201

89

700

356

1.2

3371

1980 *

132

57

471

368

375

886

4

1

388

233

1370

1545

3.8

2450

1981 *

125

33

255

143

79

207

1

0

184

114

644

497

2.5

5030

1982 *

223

138

441

164

198

327

3

1

379

121

1244

751

3.7

4927

1983 *

197

92

296

150

227

256

22

1

367

293

1109

792

6.7

8460

1984 *

183

105

460

264

148

303

2

0

370

203

1163

875

5.1

5829

1985 *

146

47

163

67

72

86

2

0

139

42

522

242

1.3

5372

1986 *

146

36

151

48

121

152

5

1

195

56

618

293

1.4

4778

1987 *

99

41

168

136

105

96

2

0

110

46

484

319

1.6

5016

1988 *

143

21

164

48

104

86

6

0

142

127

559

282

1.4

4965

1989 *

237

64

192

39

135

117

12

1

230

60

806

281

1.8

6406

1990 *

225

86

311

131

152

146

28

6

285

113

1001

481

10.5

21830

1991

460

127

395

245

333

309

11

4

647

236

1846

920

3.3

3587

1992

550

309

710

680

386

1,274

133

966

1,233

1,679

3,012

4,908

25,0

5,093

1993

385

178

466

444

112

119

79

11

652

740

1,694

1,493

10,6

7,099

1994

345

170

485

352

111

84

131

50

624

459

1,696

1,114

2,6

3,334

1995

273

149

345

230

40

18

51

15

528

180

1,237

592

2,9

4,899

1996

334

204

555

477

133

300

16

1

710

400

1,748

1,381

8,2

5,937

% Change in 1996 as compared to 1995: 22 37 61 108 233 1552 -69 -93 34 122 41 133 184 21

* Only former Federal Republic of Germany (West Germany)

From: Johann G. Goldammer (Editor IFFN)

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24. November 2017/by GFMCadmin

Germany: Autonomous Early Warning System for Forest Fires Tested in Brandenburg (Germany) (IFFN No 22 – January 2000)

de

Autonomous Early Warning System for Forest Fires
Tested in Brandenburg (Germany)

(IFFN No. 22 April 2000, p. 84-90)

Abstract

Forest fires cause significant economic damage and hazard to environment all over the world. Apart from preventive measures, early warning and fast extinction of fires are the only chance to avoid major casualties and damage to nature, especially in regions with dense population. As a common method, trained staff observes the endangered areas. In Germany alone, several hundred observation towers were erected in the forests. The staff works up to 12 hours per day and usually under difficult circumstances (extreme temperatures, isolation, continuous concentration).

To date, all attempts to develop a technical system for this task have failed to outlast the test stage. In most cases the chosen components do not work reliable enough. The Autonomous Early Warning System For Forest Fires AWFS described herein is based on new concepts of hard- and software. It is adapted to the specific conditions in densely wooded regions and detects fire by the trail of smoke.

AWFS consists of a rotating digital camera with a special filter and an innovative electronic system. Thus, an utmost high level of reliability is achieved. The noise is extremely low and allows high radiometric resolution (14bit). Digital data are transmitted from the camera to the computer via optical fibers and get evaluated. The necessary software forms the central component of the system. It recognizes smoke almost in real time by analyzing its typical dynamic and stochastic features. This became possible by modifying know-how gained in space projects. However, only recent development of fast CPUs and high capacity storage media allowed to finally solve complex problems of real-time picture processing at low cost. Warnings are autonomously passed over to a central unit, where an operator will evaluate them. For this purpose, comprehensive and user-optimized software was developed. It visualizes all information necessary for taking further steps and assists in decision-making.

AWFS was installed and tested on three observation towers in Brandenburg, Germany, during the 1999 forest fire season. It became apparent that the main requirement for absolute reliable smoke detection was met. The false alarm rate due to weather and harvest activities commonly remained below 1%, which is well acceptable. Other improvements will be effective soon. The testing forest authority confirmed that the system is mature for service and easy to use. The number of systems will be increased therefore. Moreover, other German states and some European countries are very interested in this technology.

Introduction

The probability of fires in forests and fields is steadily increasing due to climate changes and human activities. In Europe, up to 10,000 km² of vegetation are destroyed by fire every year, and even 20,000 to 90,000 km² in North America. Prognoses presume from the assumption that forest fires including fire clearing in tropical rain forests will halve the worlds forest stand by 2030. Vegetation fires result in high human death toll, speed up the extinction of species and worsen the greenhouse effect. Approximately 20 % of the CO2 emissions into the atmosphere are released by forest fires, estimated the Enquiry commission “Prevention To Save The Earth Atmosphere” of the German Bundestag in 1990. Germany, too, will be affected by the impacts of global climate change. In Brandenburg and some other German states enormous economic damage is caused by forest fires. For instance, in Brandenburg alone more than 1,000 forest fires are registered every year. 90 % of them are caused by human activities. Large fires cause a total damage of up to 70,000 DM/ha. The annual financial loss caused by forest fires in Germany amounts to a two-digit number of millions. However, preventive and fire extinction measures cost even several times this sum.

In order to minimize damage, forest fires must be recognized as soon as possible (within a few minutes). Therefore, great efforts are made in all respective regions to achieve early recognition. Although numerous technical methods were tested, reliability was in no case sufficient to develop a product suitable for the German market. As an example, infrared sensor systems tested in Spain can only detect the fire itself. However, smoke is the feature relevant for early recognition of fires in densely wooded areas. Optical systems as AWIS in the Netherlands (Breejen et al. 1998) and Firehawk in South Africa are also in a test phase. But they often imply a high rate of false alarm caused by clouds, light reflection, agricultural activities and industrial plants.

In Canada and Russia an early warning system based on aircraft patrolling is used, which means late recognition of forest fires though and is expensive to operate. Evaluating satellite data is also not very successful, as spatial and time resolution are not sufficient to allow local prevention. Moreover, clouds obstruct the view very often. . However, with the German project BIRD a new generation of imaging infrared sensors for Earth remote sensing objectives including is developed (Briess et al. 1999). A major intention of the BIRD is to demonstrate the scientific and technological value and the technical and programmatic feasibility of fire detection of under low-budget constraints. The start of this small satellite mission is planned for the end of year 2000. Within the European project FUEGO an operational mini satellite constellation is studied (Gonzalo 1996.). It will become operational in 2004 to provide early fire outbreak detection and high resolution fire-line monitoring. Hence to date experienced fire-watchers are employed everywhere in the world to observe endangered forests. In Germany several hundred observation towers are manned during main forest fire season. The fire-watchers observe the forests up to 12 hours per day under utmost difficult circumstances (extreme temperatures, awkward hygiene conditions, isolation, only short breaks from concentration) and report about any smoke formation. Apart from that, authorities usually have to spent large sums on the construction of observation towers, as these edifices need to be built, maintained and operated in accordance with relevant legislation and regulation. As an example, approximately DM 350,000 are required to build one observation tower in Brandenburg.

The pilot project “Autonomous Early Warning System For Forest Fires” (AWFS) was ordered and supported by the forest authority of Peitz, Brandenburg, and promoted by the European Union. It comprised installation and testing of a system for the following tasks:

Observe the forests autonomously and reliably for smoke formation

Recognize fires early, reduce the risk of human failure and thus minimize damage

Improve the working conditions of the staff

Reduce observation costs

A solution for this complex undertaking was found by further developing know-how from unmanned space missions and consistently adapting it to the problem of forest fire recognition.

Technical description of AWFS

According to the forest authoritys specification, an autonomous early warning system for forest fires must meet the following technical requirements:

Automatically recognize smoke formation of 10 m expansion by daylight within a radius of 10 km and within 10 minutes after becoming visible

High reliability in respect of fire recognition

Acceptable rate of false alarm

Localize the source of the fire

Easy maintenance

Autonomous transmission of smoke data to a control center

Full record-keeping of all events

Data transmission to control center must enable the operator to independently evaluate the potential hazard

System concept

Principally, there are various methods suitable to recognize vegetation fires, e.g. analyzing picture information provided by digital cameras or by infrared imagers, or detecting emission lines of conflagration gases, or active measurements with Lidar evaluating the laser signal backscattered from smoke particles. To find out which method is suited best, several preliminary tests were performed observing controlled fires with various sensors (CCD-camera, IR-radiometer, IR-spectrometer). We had to take into account our own results as well as experience gained internationally on the field of early forest fire recognition, also given facts on site in Germany, the technical requirements mentioned above and the required user-friendliness and economic efficiency. Bearing all this in mind, we chose a sensor type based on a digital CCD-camera with high resolution. Smoke detection within the visible spectral region is especially important in densely wooded forests, as open flames (which IR-sensors respond to) give alarm too late. Furthermore, cameras provide the operator in the control center with expressive images and hence make it easier for him to evaluate the situation. It was one of the projects main objectives to allow human contribution in a suitable way during the process of evaluating the alarm and selecting the appropriate fire fighting method. For such purpose, the control center is equipped with a number of computer-assisted supports.

Fig.1. Digital CCD-camera

The digital high resolution Frame Transfer CCD-camera with special filter (see Figure 1) scans the forests from the top of the observation tower. AWFS can also be mounted to braced poles of mobile phone providers, high buildings or other suitable locations. The images are resolved with 14 bits and transmitted via optical fibers to the computer unit which is located in the tower too. There they get analyzed by means of specially developed software. If there seems to be a smoke formation, compressed pictures and further details (time, position) are reported via ISDN to the control center, where they are processed in a PC displayed on the screen. The operator receives all information he needs to make decisions. Currently, one control center can support up to 7 towers. In each tower up to 8000 digital images with a data volume of 16 GByte are produced and evaluated every day.

Hardware components installed in the observation tower

The basic components of AWFS are shown in Fig.2. The most distinctive feature of the CCD-camera is its innovative electronic concept of four functional groups: CCD-head, clock-driver, analogue signal chain and controller. The camera is mounted on the very top of the tower by means of a pan and tilt unit (PTU). It takes the camera approximately 10 minutes to come full circle. The controller generates or manages all digital control signals for the CCD transport cycles, analog signal processing and PC-interface. Incoming commands are interpreted and carried out. The video signal is pre-processed in the signal chain on analog basis, then submitted to correlated double sampling, before it runs through further conditioning and multi-level filter. After the signal is digitalized in a 14bit analog-to-digital converter the image data are serialized and transmitted to the controlling PC via optical fibers.

Fig.2.Basic components of AWFS

The electronic components are utmost resistant against environmental conditions, stand out for their low energy consumption and extremely low noise. Due to the high radiometric resolution (~16,000 different grey scale values) the camera covers a wide range. Even very structures can be resolved under all sorts of lighting conditions. The 70 mm objective with 10° field of view allows 2 m geometric resolution in 10 km distance. Tests confirmed that the red-free filter increases the contrast between vegetation and smoke, as red light is hardly reflected at all by chlorophyll.

The pan and tilt unit can be positioned with a relative precision of up to 0.2° and with an absolute precision of 1° after being oriented in the landscape by means of GPS-defined land marks. During scanning stage three single images are taken in 1-second intervals for every camera position. Then, full image information is transmitted to a controlling PC at the tower bottom, where the data are evaluated, stored and passed on to an image processing computer. Both computers work with the operating system MS Windows NT.

Moreover, the controlling PC covers the following functions:

Autonomous control of camera image taking

Autonomous control of the pan and tilt unit

Compressing alarm images before transmitting them

Control of alarm data transmission (time, location of smoke etc.) to the operator in the control center

Autonomous transmission of sensor unit operating data to the operator (e.g. failure alarm)

Data transmission to the PC in the control center is currently achieved by a wired ISDN-connection. However, it is also possible do use radio transmission or other specific networks.

Image processing software

The image processing computer uses complex algorithms to identify smoke in real time. Simultaneously, it calculates the optimum exposure time and sends it to the controlling PC. The image processing software is the heart of the AWFS. It evaluates in only a few seconds typical features like dynamic and stochastic behaviour. In every camera position several images are taken. First of all, exact matching must be achieved for the images taken from the same camera position, because the towers tend to swing considerably in the wind. Next, the horizon line is determined in the image for orientation purposes. The smoke is identified then by means of dynamic and structural features and by its grey scale value. It is prerequisite to reliable recognition that several features are taken into consideration.

In a first step, typical features of smoke are looked for by analyzing a standard difference image. Wind and thermal convection of hot smoke gases change the grey scale value of smoke areas in the subsequent images. However, other environmental phenomena (e.g. clouds, wind, dust formations, reflections, bird flights, cars) can cause similar effects for short periods of time (in comparison with the time scale of the dynamic behaviour of smoke). Moving objects (cars, planes, birds) can be eliminated by an additional evaluation of the third image, because smoke is quite stationary within the time between first and last image (several seconds). Irrelevant space frequencies are eliminated by band-pass filtering the standard difference image. As the special red filter reduces the green colour of the forest significantly, smoke of wood fire always stands out against the surrounding forest. This fact supports additional suppression of interfering signals (as an example, smoke is easy to distinct from cloud shadow therefore. Finally, adaptable threshold values prompt the decision, whether fire alarm is to be released or not.

In a second step, the texture is evaluated. The respective method is based on the structural analysis of the texture of smoke, which can be clearly discerned from the surrounding structures. It works even without any comparison image and hence does not react to changes in illumination nor to moving objects like vehicles. From mathematical view, the structures are described as stochastic effects superimposed to the average grey scale value. Therefore, it is first necessary to calculate the estimated average grey scale value, so that the stochastic arises from the difference between the original and the estimated image. The mathematical basis is explained by Hetzheim (1999). Typical smoke structures are separated then by means of various procedures. A second image, which is prerequisite to the first step described above, are reused to verify the results.

In accordance with the observed features both methods proceed classing the identified possible smoke areas with probabilities. These are condensed to one total probability then. As an example, the total probability is low, if the identified areas do not overlap and clearly differ in size.

Each of the two methods described above works sufficiently enough to detect smoke on its own, but their simultaneous employment increases the reliability of smoke detection considerably.

Control Center

The control center, too, is equipped with a PC and appropriate software. It deals with the following tasks:

Control of several camera locations

Receive alarm images and data

Visualize alarm images in a suitable way and in correlation with digital maps

Display a low resolution panorama view of all towers administrated by the center

Manual area definition in order to permanently mask smoke of irrelevant origin (chimneys, villages, etc.)

Provide the operator with tools for adequate evaluation of images (zoom, image sequences, filters, facilities to change contrast and brightness)

Display the bearing lines of alarm messages on digital maps

Fade-in additional information and data bases in accordance with the users requirements

Fig.3. Fire detection from Kathlow tower on 8 August 1999

By means of the software developed for the control center, even operators who might not be familiar with modern PC-technology can easily make themselves acquainted with their scope of duties within a few days. Their knowledge about local conditions as well as the information the system provides them with enable them to soon make qualified decisions on initiation of fire fighting activities. Annex 2 shows a possible display variant on the monitor.

Results and discussion

Only practical operation can demonstrate the performance of an autonomous early-warning system for forest fires. Therefore, a pilot test was started during the forest fire season 1999, after several tests with controlled fire were made. Supplementary to traditional fire watching methods, AWFS were installed on three observation towers (Kathlow, Reuthen, Jerischke) of the Spree-Neiße district in southern Brandenburg, which is a region with very high forest fire risk. The numerous open pits and power plants in this region with their dust and smoke emissions make the task of fire watching especially difficult. The control center is located at the premises of the local forest authority in Peitz. The test results were monthly evaluated and reported in cooperation with the responsible officers.

In the test region 16 forest and field fires happened. All these fires were detected and indicated by the AWFS within the set time limit. Despite the approximately 10 min time of revolution, fire indication sometimes (especially during late afternoon) was given even earlier than by the experienced observation tower staff, who obviously suffered from symptoms of tiredness. Figure 3 is an example of automatic smoke detection.

False alarms mean a specific problem. One differentiates between alarm due to irrelevant smoke sources, e.g. chimneys, and proper false alarm. Irrelevant smoke sources are usually stationary objects. Therefore, a facility was created, that allows the operator to permanently mask these sources. The complex image analysis during which various features are evaluated in a multi-step process has been described above and proven to efficiently avoid potential false alarms.

Figure 4 presents the statistical evaluation of the false alarm rates at all three pilot project locations during the period from 16/8/1999 to 18/9/1999 (end of forest fire season). For most days the rate of false alarm is clearly less than 1%. About 230 decisions about smoke formations are to be made hourly by the software on each tower. A rate of 1 % means approximately 2 false alarms per hour, which the operator can easily cope with. However, under certain weather conditions the number of false alarms increases due to light reflection, ascending water vapor (after short but heavy rain) or low clouds. Dust formation as a result of harvest activities can be taken for smoke, too. Even experienced staff has often considerable problems to differentiate properly though. The region around Kathlow has higher rates, which is due to Cottbus city and the Jänschwalde open pit and power plant being in the range of view of the camera. The option to mask such smoke sources was not entirely used yet in the pilot project.

Fig.4. Number of days with different rates of false alarm at the different AWFS locations from 16 August to 18 September 1999

Any problems occurring were continuously evaluated during the test stage and the software improved accordingly. As a result, the user was satisfied with the AWFS.

All in all, AWFS offers the following advantages:

Reliable and flexible observation of regions with high forest fire risk, prepared for service at any time of the day

Omission of jobs with difficult working conditions, creation of new jobs in equipment production and maintenance as well as in the control center

No need for observation towers in forest regions, low costs for installation and maintenance (braced poles of mobile phone providers)

Further development

The test-stage turned out to be successful. The experience gained will be considered and evaluated during the next few months. A new generation of AWFS will be developed and tested.

Here are the focal points of future development:

The computers of several towers will be concluded in a direct network, so they will be able to control the operation of each other (watchdog-system) and hence further increase reliability in service

High performance PCs will be used, which will lead to lower turn-around times

False alarm rates will be still reduced by further development and optimization of the software, making use of the comprehensive image data base

Reliability of smoke detection will be further improved by means of a neuronal algorithms for classification

Due to its universal basic structure, AWFS can be used in other areas as well. The concept of the system (digital camera with high spatial and radiometric resolution, wide range in brightness, real-time image processing, autonomous alarm signal transmission to a control center) and the experience gained so far in detecting complex structures in natural environment are suitable for various observation tasks, e.g. environmental monitoring or security duties. The system can not only observe sensitive areas, but also autonomously give alarm, transfer data to any other place and selectively store images.

References

Breejen, E. den, Breuers, M., Cremer, F., Kemp, R.A.W., Roos, M., Schutte, K., and Vries, J.S. 1998. Autonomous Forest Fire Detection. In: Viegas, D.X. (Ed.), Proceedings of the III International Conference on Forest Fire Research and 14th Conference on Fire and Forest Meteorology held in Luso, Coimbra, Portugal on 16-20 November 1998, pp. 2003-2012.

Briess, K., Bärwald, W., Gerlich, T., Jahn, H., Lura, F., and Studemund, H. 1999. The DLR Small Satellite Mission BIRD. Proc. of 2nd IAA Symposium on small satellites for Earth observation, Berlin, April 12 – 16, p. 45-48

Gonzalo, J. 1996. FUEGO programme. Proc. IAA Symp. on Small Sat. for E. O., Berlin 1996, IAA-B-902.

Hetzheim, H. 1999. Analysis of Hidden Stochastic Properties in Images or Curves by Fuzzy Measures and Functions and their Fusion By Fuzzy-or Choqut Integrals. Proc. , 5th International Conference on Information Systems Analysis and Synthesis, Orlando, Florida, pp. 501-508.

E. Kührt, T. Behnke, H. Jahn, H. Hetzheim,
J. Knollenberg, V. Mertens, G. Schlotzhauer
Deutsches Zentrum für Luft- und Raumfahrt
Rutherfordstr. 2
D-12489 Berlin
GERMANY

and

B. Götze
INO control GmbH
Schulstr. 6
D-01728 Possendorf
GERMANY

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Country Notes
IFFN No. 22

24. November 2017/by GFMCadmin