Influence of a Multipurpose Retention Reservoir on Extreme River Flows, a Case Study of the Nielisz Reservoir on the Wieprz River (Eastern Poland)

Abstract

The objective of this paper is the assessment of the effect of a multifunctional mid-size retention reservoir on the occurrence of floods and low flows. The study object was moderate size reservoir located in Nielisz in eastern Poland on Wieprz river. The analysis conducted for the hydrological period 1976–2014 showed a positive effect of the reservoir on compensating low flows. In gauging sections located below the reservoir, streamflow droughts almost completely disappeared. The anti-flood function is particularly evident in the case of small floods, and involves a delay in the occurrence of cumulative flow, without reduction in flood volumes. Mean flow fluctuations decreased, while environmental flows were continuously ensured.