Hydrological Conditions of the Pietraszki Water Reservoir Designed for the River Sufraganiec (Kielce)

The Pietraszki water reservoir is designed for the lower part of the River Sufraganiec catchment (61.43 sq km), in the area of Kielce. In those conditions water volume is designed to be about 1.4 hm³, and the reservoir’s maximum depth, 4.2 m. The hydrological characteristics of the ungauged catchment of the River Sufraganiec are based upon the results of stationary field observations held in the cross-section located in the same place as the designed dam head. In the present analysis GIS techniques were also used, based on data obtained from the city’s Spatial Information System and WIOŚ in Kielce. Based on the Digital Elevation Model done with Airborne Laser Scanning, the reservoir area has been designated and its bathymetric and volume curves calculated. The mean annual values of specific runoff (8.8 l s⁻¹ km⁻²), runoff coefficient (39%), runoff volume (17.2 hm³), specific discharge and the filling time have been determined. The analysis also took into account the annual cycle characteristics including minimum in-stream flow calculated with the use of a number of methods. The performed analysis shows that the River Sufraganiec water resources are enough for the fast filling of the Pietraszki reservoir (depending on the season—from 22 to 114 days), even when applying the most restrictive criteria in minimum in-stream flow calculations. The ecological quality of the River Sufraganiec water in 2014 did show any significant environmental threats. The analysis shows that the quantity and quality of the River Sufraganiec water is enough for the proper functioning of the planned reservoir.