Comparison of the Curve Number Method (SCS-CN) Modifications and the Application of Measures for Soil Erosion Reduction and Flood Protection in Small Ungauged Catchments in the White Carpathian Mountains in Slovakia

Abstract

Knowledge of soil erosion and runoff processes leads to changes in attitudes towards a rational use of soil. Agricultural practices have a wide range of negative environmental impacts, including accelerated soil erosion, degradation, and increases in the volume of surface runoff. It is, therefore, necessary to investigate these negative influences on arable land. The study area is the municipality of the village of Vrbovce. It is situated in the north-western part of Slovakia in the White Carpathian Mountains. Due to its specific geological (heterogeneous rock masses of flysch) and geomorphological conditions (hilly country, uplands), that part of Slovakia is prone to accelerated soil erosion and mud flood formations. Nevertheless, a significant part of the municipality of Vrbovce is classified as agricultural land. The aim of this study is the soil erosion and runoff volume modelling that is focused on changes in the land cover/land use. We calculated soil loss with the Universal Soil Loss Equation (USLE) for agricultural parcels in the cadastral area of the village of Vrbovce. We are offering a set of suitable measures and agricultural procedures for this area as a result of our research. We estimated the direct runoff for the Teplica River basin up to the Teplica water gauge and five ungauged subcatchments in the cadastral area of the village of Vrbovce (Haluznikov creek, Lulovský creek, Zahutník creek, Zápasečník, and an unnamed creek). The Teplica river is poorly gauged with only a 10-year observation period. That length of hydrological measurements is not enough for the required period for calibrating a hydrological model. We used 3 modifications of the curve number (CN) method for estimating the volume of the direct runoff with various return periods, i.e., the standard CN method with values for the current land use, the worst land use an alternative, and the DesQ program method. We also applied the Pearson Type III distribution for the estimation of the peak flow with a higher frequency of occurrence for the Teplica gauging station. The results of the specific runoff were compared with the values of the specific runoff calculated for the Sobotište water gauge, which is situated downstream of the Teplica river. The results show that the most suitable modification of the CN method is the standard CN method with the use of the values for the current land use. The predictions of the long-term average annual rate of erosion on each parcel from the land parcel identification system (LPIS) were calculated by the Universal Soil Loss Equation (USLE).