Spatial and temporal estimation of flooding and erosion susceptible areas by application of a physically based distributed model

Floods and especially flash floods can have devastating consequences on the economy, environment and people. A physically based distributed model of runoff, erosion and sediment transport was established by the joint application of the SHETRAN river basin modelling system and Geographic Information Systems (GIS). This model was used for the recognition of the flooding and erosion/deposition susceptible areas as well as soil water content in a 114.31 km2 mountainous torrential catchment of the Lukovska River in Serbia. Given that in small water courses flash floods account for over 80 % of the total annual sediment transport the model was calibrated using the example of a storm event from 1986 and validated for three other storm events in 1974, 1976 and 1979. The model calibration and validation for the hydrological section of the model was performed by comparing the measured and the simulated values of discharges, while the model calibration and validation for the sedimentation section of the model was performed by comparing the measured and the simulated values of sediment concentrations at the outlet point of the basin. The ArcGIS software ArcView 10 was used both for preparing model parameters related to the physical characteristics of the catchment for each grid cell and for displaying and visualising the results of the model. The obtained results of runoff and sediment concentrations in a flow at the catchment outlet show good agreement with their measured values. The spatial and temporal distribution of water depths, soil water content and erosion intensities were identified for the calibration storm event, during which 67.5 mm of rain fell in only two hours. The peak of the produced torrential wave was 69.2 m3/s. The estimated maximum water depth in streams was 3.7 m. The simulated erosion rates were within the range of 1 to 11 t/ha and they corresponded to the observed rates of erosion in Europe during extreme rain events. The areas that are flood prone and susceptible to intensified erosion were identified. The presented methodologyis useful in identifying the flooding and erosion vulnerable regions in a catchment on the basis of which relevant decisions regarding water and sediment management can be taken