332 IMPACTS OF THE RESERVOIRS ON THE RIVER LOW FLOW AND MEASURES TO MITIGATE THE NEGATIVE EFFECTS TĂNASE ILEANA 1 , ZAHARIA LILIANA 2 ABSTRACT. – Impact of the reservoirs on the river low flow and measures to mitigate the negative effects. This paper aims to highlight the impacts of the reservoirs on the low flow downstream of dams. It is based on the analysis of the flow data sets (mean daily and monthly discharges, minimum monthly discharges) provided by gauging stations located downstream four reservoirs in Romania: Gilău, Siriu Pecineagu and Surduc. Statistical methods and comparative analyzes of low flow parameters in natural regime and modified regime were mainly used. The results show that the impacts are differents from one case to another. Generally, the flow decrease significantly in modified regime, mainly in spring and summer periods (the breeding period for most aquatic species). This occurs downstream of the reservoirs Surduc, Gilău and Pecineagu. In the case of Siriu reservoir, the impact of the dam construction on the low flow is less significant, and the low flow in modified regime are higher that in natural regime. Keywords: low flow, reservoirs, impact, Romania. 1. INTRODUCTION The dams and reservoirs represent one of the most significant human interventions in the hydrological cycle. Although the economic benefits of the reservoirs are undeniable, they cause quantitative, qualitative and ecological significant changes to the rivers. While in the past, the dam design and operation did not take into account the environmental issues, in the last decades, an increase in environmental awareness has led to the recognition that the management of water resources includes a responsibility to protect the natural resources that depend on water, from impacts that causing degradation (Sally, 2000). This paper aims to highlight the impacts of the reservoirs on the low flow in the different geographic regions of Romania. Based on the knowledge of this impacts, appropriate measures to mitigate the negative effects of the reservoirs could be considered. 2. DATA AND METHODS The study is based on the flow data series (mean daily and monthly discharges, minimum monthly discharges) recorded at the gauging stations located 1 University of Bucharest, Faculty of Geography, Bucharest, Romania E-mail: ileanatanase@ymail.com 2 University of Bucharest, Faculty of Geography, Bucharest, Romania E-mail: zaharialili@hotmail.com