Journal of Maps, 2010, 520-530

Geomorphological map of the Wustebach (Nationalpark Ei-fel, Germany) - an example of human impact on mid-Europ-ean mountain areas

FRANK LEHMKUHL, DAVID LOIBL and HOLGER BORCHARDT

Physical Geography and Geoecology, Department of Geography, RWTH Aachen University, Templergraben 55, D-52056 Aachen,Germany; flehmkuhl@geo.rwth-aachen.de.

Abstract

Two detailed maps illustrating the geomorphology and hydrology combined with land-use covering 2.5km2 of the small upper catchment of the Wustebach in the Nationalpark Eifel, Germany, are presented.The maps, at a scale of 1:5,000, are based on the “Deutsche Grundkarte 1:5,000” official topographicmaps and a digital elevation model. The first map depicts hydrology and land-use, whilst in the secondmap the geomorphology is combined with slope angles. Hydrologic and geomorphologic informationis based on field mapping while land-use was mapped using aerial photographs. The study site can besubdivided into an upper part characterized by small gentle shaped valleys in the south and a lower partcharacterized by V-shaped valleys in the north. Numerous charcoal kilns and a few sunken roads showthe human influence on the landscape from medieval to modern times. The area was strongly deforesteduntil the mid-19th century. In addition, several dugouts, foxholes, gun emplacements, and impact cratersshow the strong human impact on the landscape during the Second World War.

(Received 22nd December 2009; Revised 8th June 2010; Accepted 10th June 2010)

ISSN 1744-5647doi:10.4113/jom.2010.1118

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Journal of Maps, 2010, 520-530 Lehmkuhl, F., Loibl, D. et al

1. Introduction

The study site, the upper catchent of the Wustebach in the Nationalpark Eifel, is the sub-ject of several geoscientific research projects, focussing on soil, vegetation, hydrology,and geomorphology. Each of these aspects is influenced by intensive human impact,which distinctively altered the area’s microrelief and the local geomorphologic processsystem during the last centuries. Thus, the need for a map providing information onthe kind and distribution of anthropogenic modifications was evident. To meet this de-mand, we mapped the most relevant geoscientific parameters in a consistent and clearway. The “GMK 25”, a sophisticated system for geomorphologic mapping at a scaleof 1:25,000 developed in Germany during the 1970s and ’80s, served as conceptual fra-mework but had to be modified to meet the project requirements in scale and content.This resulted in two map sheets, one presenting the hydrography and land-use (Map1), the other depicting the human impact on the landscape in an applied geomorphicmap (Map 2). These maps record the geomorphologic characteristics of the catchentand create a knowledge base for further investigations in this typical mid-Europeanmountain region.

2. Study area

2.1 Climate and geology

The study site, extending over an area of 2.5 km2, contains the uppermost catchment ofthe Wustebach River, located in the southernmost part of the Nationalpark Eifel closeto the German-Belgian border (Figure 1). Situated in a low mountain range, the highestpoint of the catchment is 630 m asl in the southern part and the lowest part is about 550m asl in the northern part of the river valley, respectively.

The present climate is characterised by oceanic influences. The mild and humid climateis controlled by westerly cyclones. Mean annual air temperature is relatively low andreaches less than 7◦C. The mean annual precipitation is about 1200 mm (Havlik, 2002).

In terms of geology the area in the northern Eifel Mountains belongs to the Rhenish Mas-sif, which is part of the Variscan orogenic belt in north-western Europe. The study areais characterised by a differentiated petrography of the so-called “Wustebachschichten”comprising Lower Devonian foliated siltstone and clay rock (schist and slate). Gleyicand semigleyic soils (gleysols and planosols) have developed next to rivers, brown-

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Figure 1. Map of the investigation area in the Nationalpark Eifel.

earth types (cambisols) can be found on hill slopes and tops (soil maps: Schalich, 1988;1991; Richter, 2008).

2.2 Socioeconomic conditions and history of human impact

The climatic conditions described above, and the infertile soils, result in poor agricul-tural land. Economic development is affected by these natural aspects. In addition,socioeconomic conditions, like small and scattered field structures, a low populationdensity, a poor road system and long distances to the markets affected the economyduring medieval and early modern times (Schwerz, 1836; Baur, 1928).

The beech trees of the Eifel were used for charcoal production. Until the mid-19th cen-tury the northern part of the Eifel Mountains and its foreland had been one of the firstcentres for iron melting and other heavy industries using huge amounts of charcoal.The Eifel Mountains were largely deforested during this period, worsening the agricul-tural situation. Under Prussian reign since 1815, spruces were planted to improve this

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situation and to use the fast and straight growing wood for mining and construction(Schwerz, 1836; Baur, 1928; Nilson, 2006).

Between 1938 and 1940 the “Westwall”, a fortification line along the western border ofGermany, was constructed and crossed the study area in its south-western part (Großet al., 1998). In the final stage of the Second World War heavy fighting took place inthe region during the Battle of the Bulge (Ardennenoffensive, 16.12. - 27.12.1944) (Ho-henstein and Trees, 2008). After the war the few remaining trees were cut down. In the1950s, Norway spruces (Picea abies) were planted again to support local forestry. Since1.1.2004, the area became part of the Nationalpark Eifel. It is planned to deforest the 60year old spruce trees in order to speed up development into a natural forest of beech(Fagus sylvatica) and birch (Betula pubescens) as the potential natural vegetation cover.

3. Methods

The geomorphology of the area has been mapped during a field-campaign supportedby a digital elevation model (DEM) of 1 m horizontal and 15 cm vertical resolution.The mapped geomorphology was field-checked during 2007 and 2008. We used thegeomorphological map of the Federal Republic of Germany 1:25,000 (“Geomorpholo-gische Karte der Bundesrepublik Deutschland 1:25.000”, GMK25) as a conceptual basisfor the geomorphological field survey and the resulting map (Leser and Stablein, 1975;Barsch and Liedtke, 1980). The legend of the GMK25 is one of the most sophisticatedguidelines to geomorphological mapping, containing eight layers of information (to-pography, slope angles, landforms, curvature, substrate, geomorphological processes,hydrography and areas of similar genesis) depicted in a single map sheet through anelaborate set of rules prescribing the use of colours and shapes. Still, its complexity andthe enormous effort necessary to produce a map remain significant weaknesses (seeHagedorn and Lehmeier, 1983; Lehmkuhl, 1998).

Considering the aim of creating a clear overview of the relevant geomorphologic fea-tures we decided to integrate only the layers directly relevant to the subsequent studies.Thus, the layers containing curvature and areas of similar genesis were omitted dueto their lack of informative value. Our field campaign showed that the recent localgeomorphological processes are not dominant enough to legitimate their mapping. Ad-ditionally, local substrates were subject to an investigation of the Geological Survey ofNorthrhine-Westfalia (“Geologischer Dienst Nordrhein-Westfalen”) resulting in a spe-cialized map on this topic (Richter 2008), which made a survey on this topic obsolete.On the other hand land-use, not being a part of the GMK25-concept, was evaluated tobe an important information category by researchers involved.

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Due to the focus on microscale landforms and the relatively small extent of the studyarea we decided to use a consistent scale of 1:5,000 instead of 1:25,000. First field ob-servations showed that typical relations between genesis and morphography of specificlandforms exist. For example, all charcoal kilns have approximately the same diameter.Thus, point symbols showing the genesis of an object were considered an adequate andclear symbology in this study.

Basic information, such as logging roads and rivers, are based on the 1:5,000 topo-graphic map (“Deutsche Grundkarte”); sheet Wahlerscheid (No. 5403-32) and Sonn-tagshugel (No. 5404-31). The contour lines were generated from the DEM. Data onland-use type was obtained from aerial photographs, whilst slope angle was calculatedfrom the DEM (Burrough and McDonell, 1998). In order to ensure the readability of themap to non-geomorphologists, we decided to split the gathered information into twothematic maps: 1) Hydrology and land-use and 2) Geomorphologic situation and slopegradient.

The cartographic framework (projection, scale, coordinates, etc.) provided by the “Deut-sche Grundkarte” was retained in the design process. The depiction of geomorphicfeatures was inspired by the GMK25 guidelines, however due to the large scale of themaps and the small diameters of the relevant features, we did not follow these guide-lines for areal features, requiring the delineation of landform borders. Instead, we useda set of genetic point-symbols centred in the middle of the features.

The colours used were chosen to comply with cartographic standards. Thus we used thepalette of the official German topographic and cartographic information system (ATKIS)to display the land-use (http://www.atkis.de/). For slope angles, a partly transparentyellow to orange gradient was chosen to correspond to common viewing habits tendingto associate steep slopes with reddish colours. Transparency was used to make surecontinuous colours did not overly dominate the overall design. The maps are intendedto be printed at A1 size for optimal readability.

4. Discussion

4.1 Hydrography and land-use

The hydrography of the upper catchment of the Wustebach is shown in Map 1. Thestudy site’s drainage pattern is dendritic with one second-order stream according toStrahler (1957) in the north-western part of the study area feeding the main channel.The study site can be subdivided into an upper and a lower part: the upper part is lo-

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cated in the south and characterized by small gentle shaped valleys, whereas the lowerpart in the north is characterized by V-shaped valleys (Map 2). The headwater of theWustebach originates in a flat area including several springs and wetland at about 610m asl. Anthropogenic modification of the drainage system comprises artificial ditchesbesides logging roads (drainage), upslope of meadows (irrigation), and in the forest(drainage). The latter were constructed in the 19th century to support the growth ofspruce trees in this wet region; not all of them were mapped due to their small scale.The two small lakes along the river are remnants of a static fire tank and a possibleformer fish pond.

Forestry has dominated the study area since the 19th century. About 87% of the catch-ment is covered by 60-year old spruce forest (Picea abies) (Figure 2). In the northern partthere are meadows along the main course of the river (Map 1, Figure 3). They coverabout 6% of the investigation area. In addition, there is a small alder forest with half-bog (Alnus glutinosa) and a small peat bog in the vicinity of the river in the central partof the study area.

Figure 2. 60-year old planted spruce forest on gentle slope in the upper catchment of the study area.

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Figure 3. Meadow and spruce forest in the central part of the investigation area.

4.2 Landform descriptions

The main valley of the Wustebach is an asymmetric V-shaped valley (Map 2). The eas-tern slope is steeper (11 - 15◦) than the western slope (7 - 11◦, Map 2). The westernslopes and the top of the valley are comprised of small gentle shaped or trough shapedperiglacial valleys.

The main small-scale geomorphic features mapped are of human origin. On the easternpart of the study area several charcoal kilns were mapped showing medieval to mo-dern anthropogenic land-use. Sunken roads, possibly from medieval or even Romantimes, cross the main river’s upper catchment and the northern part of the study area,functioning as main routes for discharge and soil erosion.

Further human impact on the landscape occured in the 20th century (see above). Fourbunkers of the “Westwall” (the southernmost and the eastern ones for the water supplyof the fortifications) were mapped (Figure 4). Several dugouts (Figure 5), foxholes, im-pact craters (Figure 6), and gun emplacements (as hollows or landfill) show the stronghuman impact on the landscape during the Second World War.

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Figure 4. Bunker from the “Westwall” fortification on the eastern part of the study area.

5. Conclusions

We found that modifying the original GMK25 concept is an efficient way to produce ap-plied maps, even at large scales. It’s comprehensive information content combined withthe concept of independent layers, offers a highly useful basis for the selective displayof spatial distributions for a broad range of geoscientific applications. The integration ofthe land-use layer, which is not part of the GMK25 set of layers, shows that it is possibleto extend the original concept.

The mapping method applied in this study provides a means to depict the relevant ele-ments of the local geomorphology clearly and precisely, showing the massive humanimpact on the study site. Hence the resulting maps become an important source ofinformation for other research projects in the area. Furthermore, the analysis of spa-

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Figure 5. Dugout from the Second World War in the south-western part of the study area.

tial distributions shown in the maps inspired several new investigations regarding theinfluence of anthropogenic landforms on soil, interflow, and discharge.

Software

The maps produced during the field campaign were scanned, optimized and saved inTIFF-format using Adobe Photoshop. The resulting images were then georeferenced inESRI ArcGIS 9.3 and provided the basis for digitization of the mapped features to vectordata (shapefiles). A layer of classified slope angles was calculated automatically fromthe DEM using ArcGIS Spatial Analyst, aided by PCI Geomatica 10.1 for generalizationof the high-resolution output file. The final layout of the map was conducted in ArcGIS9.3, applying the set of symbols provided by Otto (2004) supplemented by additionalones to represent the specific geomorphological characteristics.

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Figure 6. Impact crater in the central part of the study area.

Acknowledgments

The authors would like to thank Dr. M. Roos from the Nationalpark Eifel for providingus with the DEM and aerial photographs. We thank F. Richter (Geological Survey ofNorthrhine-Westfalia) and G. Ahnert (Landesbetrieb Wald und Holz NRW - National-parkforstamt Eifel) for valuable discussions. We thank the four reviewers for helpfulsuggestions that improved the paper. In addition, we would like to thank all studentsfor their assistance during the “Projektstudie Wustebach” in summer 2007.

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