THE ASSESSMENT OF EROSION SEDIMENT INCOMING INTO WATER RESERVOIR BOTONEGA IN ISTRIA (CROATRIA)

摘要

The paper stresses the influence of soil erosion on water management in Istria, which is especially present in the catchment area of the largest and most important water storage basin (artificial lake) in Istria, i.e. water reservoir Botonega. The reservoir is located in the central part of Istrian peninsula where flysch geological formations are dominant. Such conditions contribute to the occurrence of erosion of various types and intensities. Therefore the assessment of the erosion sediment incoming into the reservoir is difficult and unreliable. In Croatia the assessments of erosion sediment incoming into artificial lakes are usually estimated by the parametric method of Prof. Gavrilovic. The method is briefly described in the paper and the result of the assessment is presented. The results show that the sediment incoming into Botonega reservoir could be 3 times greater than the value predicted in the design documents of the reservoir. For the minimisation of sediment incoming into the reservoir one detention dam constructed at the tail of reservoir. The measured quantities of sediment deposited behind the constructed detention dam indicate that the reliability of the estimation of erosion sediment transport according to Gavrilovic's method mostly depends on the available data on catchment area. The necessary data can be obtained by applying of the remote sensing on the catchment area and by implementation of GIS technology in procedure of evaluation of the parameters in Gavrilovic's method.