The Influence of the Vír Reservoir on Maximum Annual and Flood Discharge Rates on the Upper Svratka River

Abstract

This paper provides an analysis of maximum annual and flood discharges on the upper Svratka River during a period of systematic hydrological measurements before and after the construction of the reservoirs known as Vír I and Vír II. The water-gauge stations of Borovnice (upstream from the reservoirs) and Vír (downstream from the reservoirs) are used to analyse peak discharges (Qk) with a return period equal to or higher than two years (Q2), from 1925 to 2010. The flood regime is evaluated in terms of the frequency of floods, their seasonality and extremity. The article explores anthropogenic influence on maximum annual discharges and flood discharges on the upper Svratka River after construction of the two reservoirs, using numerical and statistical methods. These are evident, primarily, in the disruption of the homogeneity of observations, reductions in the frequency and extremity of floods, decreasing in the values and variability of maximum annual discharges, and delay in their culminations. The construction of the reservoir provides a unique example of modification of a natural hydrological regime that facilitates the quantification of an anthropogenic influence.