2.1. The Basic Space Use
The Krupanj Municipality, located in the west of Serbia, on the right bank of the river Drina, has been chosen as the case study. Due to its specific hydrological, geomorphological, and climate characteristics, it suffered considerable effects during the floods that occurred in Serbia in 2014. It has a surface of 342 km
2 and a population of 17,860. The Municipality centre is located in a basin, at an altitude of 289 m above sea level (ASL), and is surrounded by the mountains Boranja, Jagodnja, and Sokolska, with a height of app. 1100 m ASL. The rivers Bogoštica, Čađavica, and Kržava flow through Krupanj [
23]. The greatest percentage of the Krupanj Municipality territory is made up of agricultural land, app. 55%, followed by forests and forest land, app. 40%, with the rest being meadows and pastures.
Figure 1 shows land use in the Krupanj Municipality.
The growing stock consists of a mixture of beech, oak, and silver fir forest stands, while the highest altitudes of the Municipality mostly have pure evergreen stands. State-owned forests are made up of beech stands, which are the most widely distributed, followed by oak, black locust, and pine stands. The forests in the private sector (mostly beech stands) are of poorer quality, with a great many small land parcels adjacent to agricultural land. Low vegetation, mushrooms (penny bun and foxglove), as well as wild fruit species (apple, pear, sweet cherry), are some of the plant species found in the forests of the Krupanj area [
23].
Of the total agricultural land, 38.03% are farming fields, 6.95% are orchards, 0.15% are vineyards, 3.37% are meadows, 9.84% are pastures, and 77% of the total agricultural land resources are used as orchards and farming fields. The dominant cultivated fruit species include raspberry, plum, and blackberry, while the potato is the most cultivated farming species. The other cultivated species include sweet cherry, wild strawberry, wild blackberry, wild peach, apple, pear, cherry, tomato, pepper, beans, peas, cauliflower, wheat, corn, barley, oats, etc. [
23].
The mining infrastructure in the Krupanj Municipality includes the lead and zinc foundry, while the antimony mine is the most significant from the standpoint of erosion processes and sediment production. In the 1980s, the mines were closed without any reparation and recultivation of the degraded surfaces, i.e., the flotation landfill. Due to the great floods of 2014, the tailings pond dam burst, resulting in the leakage of toxic materials (lead and arsenic) and sediments into the rivers Korenita, Jadar, and Drina.
The road infrastructure in the Krupanj Municipality has a total of app. 692 km and takes up the surface area of app. 4.12 km2. It is made up of hard-surfaced and unpaved roads. Some forests and other unpaved roads turn into surface waterways as a result of high precipitation levels, causing land gully erosion. Due to surface water and groundwater infiltration, soil mass damping and saturation have occurred, resulting in the destruction of the soil structure, the appearance of landslides, land mass collapsing, subsidence, and land separation. Over the years, as a result of extensive rainfall, soil erosion, landslides, and land collapsing, the poor state of the roads in the Krupanj Municipality has become worse.
The electrical power lines (transmission lines) run across the Krupanj Municipality with a total length of 34.12 km, a surface area of 2215 km
2, and protective transmission line corridors, which make up 0.65% of the total territory of the Krupanj Municipality. Planning the construction of electrical power facilities changes the land use, and the defined type of construction and maintenance affects space, i.e., the land resources. The electrical power facilities and their routes are constructed and maintained using measures including forest cutting, routing across agricultural land, digging up soil in order to put the pylons in place, use of machinery, etc., during construction and subsequent use. Clear forest cutting, as well as the use of heavy machinery on steep terrains, increases the risks of erosion processes and sediment production. Possible implications of using heavy mechanisation and related forest management challenges were addressed in certain research papers [
25,
26,
27,
28].
Small hydroelectric plants have not been built in the Krupanj Municipality, but a total of seven are planned to be constructed. The experiences of planning and constructing (use) of hydroelectric plants in Serbia have shown that, in most cases, large degradation processes take place during construction, as well as subsequently, when they are in use. Full waterway intake, the destruction of protected plant and animal species, as well as the rest of the flora and fauna; the appearance of landslides, erosion, and the production of great amounts of sediments; the destruction of the landscape, etc., are some of the consequences of constructing certain small hydroelectric plants.
Mount Jagodnja has a ski resort, which currently has ski runs, sleighing grounds, and a ski lift to transport the skiers. Jagodnja’s peak, Mačkov Kamen, is at an altitude of 923 m ASL. The length of the ski runs stands at app. 600 m, while the paths are app. 30 m long. In order to build a ski resort with the accompanying facilities, a change was made in land management, i.e., building certain facilities meant repurposing other types of land as construction land. During the construction of the ski run and the cable, the slope was routed, trees were cut, and stumps were removed. At the time, no works were conducted to prevent erosion processes from occurring on the ski run. The ski run is not in use, which allows grass and bush vegetation to grow and develop unimpeded.
2.2. Natural Characteristics
The territory of the Krupanj Municipality is affected by the moderate continental climate, with an average annual air temperature of 10.1 to 12.0 °C and an average annual precipitation level of 960 mm. The precipitation maximum of 110 mm is reached in September, while the minimum of 44 mm is reached in winter months. The average precipitation level for the vegetation period (March–September) stands at 524 mm, and the number of days with precipitation at 195. The annual number of days with snowfall stands at 32 [
29]. The greatest amount of show in Krupanj falls in January (172 mm), February (128 mm), and December (127 mm). The number of showy days in January is around 10, in February around 8, and in December around 7. Show melt in the territory of the Krupanj Municipality does not pose a direct risk of triggering erosion processes [
30]. The higher mountain areas (Mount Sokolska and Jagodnja) are richer in precipitation than the lower-altitude settlement areas, which is the basis for positive hydrological characteristics of the wider area (the density of the hydrographic network is 0.96 km/km
2), from the standpoint of water supply, and negative ones from the standpoint of land erosion, landslides, torrential floods, etc. The mountainous environment with a specific altitude results in local air flow and more precipitation, especially during the summer (303 mm), with June having 124 mm of precipitation, while the height of precipitation in the winter is considerably lower, standing at app. 195 mm for the period between 1985 and 1996 [
23]. Dominant winds blow from east and southwest and are of weak to medium intensity (4.4 m/s–6.7 m/s), therefore not affecting the forest vegetation. Due to the neighbouring mountains, the wind in Krupanj does not trigger eolian erosion processes [
29,
31].
The Municipality relief is of the hill-and-mountain type, and in the valleys of the rivers Likodra and Jadar, it is the lowland type. Krupanj is situated in a structural basin surrounded by the mountains Boranja, Jagodnja, and Mount Sokolska, at an altitude of 289 m ASL. The highest peak of the Rađevina area is Rožanj, with an altitude of 973 m ASL on Mount Sokolska. The rivers Bogoštica, Kržava, Čađavica, and Brštica, which form the river Likodra, gravitate and flow through the town of Krupanj. From Krupanj, Likodra flows northeast and into the river Jadar, the biggest river in the area, at the village of Zavlaka. The Krupanj Municipality waterways belong to the river Drina drainage basin. The permanent and temporary waterways make the Drina very rich in waterways. The surrounding hills and mountains supply water to the following rivers: Bogoštica, Kržava, Čađavica, and Brštica. These rivers form Likodra near the town itself. From Krupanj, Likodra flows northeast and into the river Jadar, the biggest river in the area, at the village of Zavlaka. The erosion processes are pronounced, and the composition of the geological material, the terrain inclination, and the forest cover help along. In the Krupanj Municipality, a large portion of the territory is made up of dips of up to 20%, while dips of up to 21% make up a considerable share of the surface area. Such a terrain configuration, in addition to a significant impact on the waterways, results in and proves the occurrence of frequent floods and the production of considerable amounts of erosion sediments [
23].
The geological material is made up of granodiorites, around which is an area of contact metamorphic rocks, diabase, hornstone, quartz conglomerates, shale stones, and sandstones. The most frequent are granodiorite masses on which potentially nutritious soils favourable for plant production are formed [
23]. World Reference Base for Soil Resources (WRB) was used in the analysis of the land type; it is an international classification system used for the comparison with the national classification system and for defining and understanding land science terms used in the land management and protection on a global scale [
32]. The pedological characteristics point to the following types of soil:
Haplic Cambisol (Dystric)—acidic brown soil on granites and granodiorites are the dominant type in this area. The favourable water and air regime allows a mechanical composition defined as light and sandy. This type of soil is located under the hill beech forest and is characterised by high fertility, which makes it suitable for most forest species;
Haplic Luvisol (Epidystric)—the evolution of acidic brown soils results in illimerised acidic brown soil, which takes up less surface area. Oak stands are mostly found on it, while it has secondary importance for beeches;
Leptic Cambisol (Eutric, Clayic)—brown soil, which is found on bituminous and banked limestone, is characterised by lesser depth and a relatively high share of organic matter. Its chemical characteristics make it similar to rendzina, but they are different in terms of mechanical composition as it has the character of clay loam;
Haplic Cambisol (Dystric, Siltic)—acidic brown soil on Paleozoic shales is formed on acidic rocks with a very shallow humus layer with unfavourable chemical and mechanical characteristics; therefore, it has little production value;
Haplic Cambisol (Dystric, Skeletic)—brown acidic soil on sandstone is characterised by a pronounced acidity and is formed as a shallow soil with a skeleton, which puts it in the category of soils with good water and air regimes of good production value;
Haplic Planosol—the soil with unfavourable physical characteristics and a poor water and air regime; parapodzol (pseudo-clay) is a low-fertility soil. The main vegetation growing on it is made up of oak and common hornbeam forests;
Haplic Fluvisol—alluvial soil occurs in the river Jadar valley as an alluvial sediment. It is a young sediment made by frequent flooding. The groundwater, which is very near the surface, makes this soil characteristic since, during droughts, the water supply to the vegetation is very good, giving the plants enough moisture at times of drought [
33,
34].