Soil Erosion Modelling JRC Ispra 20-21-22 March 2017 University of Belgrade, Faculty of Forestry Department for Ecological Engineering in Protection of Soil and Water Resources SPATIAL AND TEMPORAL ANALYSIS OF THE DEGRADATION OF NATURAL RESOURCES IN RIVER LIKODRA WATERSHED e mail: sinisa.polovina@sfb.bg.ac.rs Siniša Polovina Boris Radić Ratko Ristić Vukašin Milčanović
The subject of this work is resource of soil, analyze of its degradation through review actual state (2012 th year) and comparation with previous state of degradation (state from 1983 th year) in watershed of Likodra river. In May 2014, the urban area and rural parts of the municipality Krupanj are afflicted catastrophic flash floods that resulted in the loss of human lives and enormous material damage. Likodra river is located in the northwestern part of the Republic of Serbia (micro-regions Rađevina) on the right bank of the Drina. Figure 1: The geographical position of the river Likodra watershed
In the analysis of the basic physical geographical parameters of the watershed used topographic maps of the Military Geographical Institute in scale 1: 25000 and a digital elevation model DEM resolution 100m, which was formed on the basis of scanned topographic maps. Parameter Mark Unit Value Drainage area А km 2 140.38 Perimeter P km 78.75 Peak point Pp m.a.s.l. 805 Confluence point Cp m.a.s.l. 160 The length of main stream L km 30.92 The shortest distance from confluence point to watershed centroid Lc km 16.13 Absolute slope of river bed Sa % 1.16 Weighted slope of main channel Sw % 2.09 Total length of the waterways L km 377.4 Density of the hydrographic network G km/km 2 2.68 Module of the watershed development Е 1.86 Local erosion base Be m 599 Mean altitude Am m 495.68 Medium altitude difference Amd m 277.68 Mean slope of terrain Smt % 19.72 Table 1. Physical characteristics of the river Likodra watershed
Analysis of relief was obtained based on DEM (Digital Elevation Model) resolution of 100 m. Figure 2: The hydrographic of the river Likodra watershed Figure 3: DEM of the river Likodra watershed
GEOLOGICAL DATA: Basic Geological Map of Yugoslavia in 1970 scale 1: 100000 (issue of the Federal Geological Institute) PEDOLOGICAL DATA: Soil map of SR Serbia in 1966 scale 1: 50000 (edition of the Institute of Soil Science in Belgrade) Figure 4: Geological map of the river Likodra watershed Figure 5: Pedological map of the river Likodra watershed
LAND USE: Corine Land Cover database All the above databases are analyzed in GIS environment Figure 6: Slope of the terrain in watershed of the river Figure 7: Land use in the watershed of the river Likodra
LAND DEGRADATION: Method Of Potential Erosion Land degradation in the study area will be analyzed using the Erosion Potential Method (EPM) (Gavrilović): Y Coefficient of the soil resistance to erosion X a The land use coefficient, ϕ Coefficient of the observed erosion process (takes visible erosion processes), Isr Mean slope of terrain Z- Coefficient of erosion Erosion category I II Qualitative name of erosion category Excessive erosion- deep erosion process Heavy erosion-milder from excessive erosion Range of values of coefficient Z Mean value of coefficient Z 1.1-1.5 1.25 0.71-1.0 0.85 III Medium erosion 0.41-0.70 0.55 IV Slight erosion 0.20-0.40 0.30 V Very slight erosion 0.01-0.19 0.01 Table 2. Classification category of erosion by erosion coefficient Z
After digitalization of maps and assigning values to certain elements, a conversion was made into raster format, resolution of 100 m where the attribute values Y and Xa were a criteria for the conversion into raster base Raster base becomes adequate for calculating erosion coefficient Z according to formula Figure 8: The Intensity Erosion map of Likodra watershed Figure 9: The Erosion classes map (Z) of Likodra watershed
In the purpose of quantification of erosion intensity changes in Likorda river watershed, by using GIS, digitalization of research area was made with Map erosion from 1983 (Lazarević, 1983). Figure 10: The severity of erosion processes in the catchment area of the river, state in 1983 and current state
Erosion category Qualitative name of erosion category 1983 current state km 2 % km 2 % I Excessive erosion- deep erosion process 0 0 0.12 0.09 II Heavy erosion-milder from excessive erosion 2.73 1.95 0.86 0.61 III Medium erosion 18.43 13.1 23.94 17.06 IV Slight erosion 72.95 52.0 38.2 27.22 V Very slight erosion 43.68 31.1 77.26 55.02 VI Accumulation of sediment 2.56 1.8 0 0 Total 140.38 100 140.38 100 Mean value of coefficient Z Zsr=0.275 Zsr=0.204 Table 2: Erosion categories in the Likodra river watershed 1983 and current state Graph 1: Comparative review of erosion categories in two periods
CONCLUSIONS Soil, as a natural resource, represents a dynamic system created in the process of the pedogenesis, and under the influence of atmospheric and biological factors is constantly changing. With a view to assess the intensity of soil erosion and to propose measures for reducing the degradation process, developed many methods for assessing erosion loss of land. The (EPM) method is suitable for the definition of erosion processes on the surfaces of a wide range of sizes. The advantage of using this method is that it does not require a large number of input parameters and possible applications of GIS. One of the many GIS task is to extract the relevant information from the complex relations between the natural and geographical phenomena and processes. Geographical information system enables all the relevant spatial data adequately systematized, analyzed and finally displayed.