Catchment-wide estimate of single storm interrill soil erosion using an aggregate instability index: a model based on geographic information systems

The main objective of this paper is to estimate interrill erosion after rainfall in the basin of Mourganis river (442 km 2 ; Kalabaka province, Trikala prefecture, Thessaly, Greece). For the estimation of the interrill erosion, the method of Valmis et al. ( 1988 ) was used, in combination with Nearing et al. ( 1989 ). Input data of the algorithm include the slope angle of the ground surface, the rainfall, the ground cover type, the height of canopy, and the instability of ground of the study area. The spatial data were processed by standard GIS software. Soil samples were collected in the field to calibrate the model. The results comprise soil erosion maps for two specific rainfall scenarios. The first rainfall scenario refers to the most extreme rainfall in this catchment that happened on the 7/21/1959 with 48 mm/h. The second scenario is closer to average as the intensity rainfall is 3.54 mm/h. The total mass of eroded material ranges from 0.048 t/ha (assuming mean rainfall intensity) up to 3.5 t/ha (for the extreme scenario). We note that the western part of the Mourgani basin exhibits higher erosion than the eastern part.