Assessment of the Flow Regime Alterations in the Veleka River, Bulgaria

The aim of the present study was to characterise the natural flow regime of the Veleka River to determine the extent of its alteration and to design environmental flow regimes to protect aquatic habitats and species. A method for hydrologic alteration estimation has been examined and applied to characterize and evaluate the hydrologic alteration of the Veleka River flow regime using streamflow series. The region in concern belongs to the South Eastern climate and is mainly transitional Mediterranean climate. In the study area there are not hydrological perturbations. The used method, referred to as the Indicators of Hydrologic Alteration is based upon an analysis of hydrologic data available from existing measurement points. The hydrological status of the Veleka River was assessed by comparing the two periods. The most significant results suggest changes in low-flows. The current flow regime shows a significant reduction of stream flows. From this study we conclude that the indicators of hydrologic alteration proved to be a useful approach, capable of focusing, comparing and establishing levels of hydrologic disturbances.