Land use change and its impact on surface runoff from small basins

Anotace: Land use changes in a basin frequently result in an increased surface runoff, which may induce the occurrence of floods or soil erosion. The paper thus aims to estimate and assess the change in surface runoff characteristics based on the analysis of land use change (between the years 1949 and 2017). The research area is represented by the small basin of Radiša watercourse (Western Slovakia). In order to estimate surface runoff, the SCS-CN method, modeling in geographic information systems (GIS) and recorded rainfall data were used. The land use was identified based on aerial imagery (orthophotos) from 1949 and 2017 showing quite significant changes. Arable land decreased the most by more than half (by 15.62%) while the share of forests increased by 4.55%, glades by 3.45% and built-up areas by 3.05%. As for the results of the SCS-CN method, the highest interval of surface runoff depth (27.1-64.4 mm) increased only slightly from 7.27% (in 1949) to 7.57% (in 2017). On the other hand, the lowest values of runoff depth (2.3-3 mm interval) covered most of the basin area in both years (60.65% in 1949 and 64.94% in 2017). The share of high runoff volume values (intervals 20.1-50 m3 and 50.1< m3) on the basin area decreased during the years 1949 and 2017 by 1.95% and by 1.05%, respectively. Based on the results, it can be concluded that the risk of surface runoff in the research area decreased over the studied period.