Summary:

This article shows analyzes the possibility of reducing the 1% frequency flood wave with use of dry storage reservoirs. Analyses were carried out in the Serafa catchment, where due to a very high degree of sealing creates a risk of flooding for residents, which showed even the flood of May 2010. The increase in the degree of sealing due to faster response to the rainfall catchment area and, consequently, higher peak flows. An alternative to increase the degree of sealing the catchment are measures to improve water retention. One such method is the construction of dry storage reservoirs. In this article was analyzing the work of these variants reservoirs - in the first scenario assumed a reservoir on the Serafa river, in the second - two dry reservoirs, one on the outlet in Malinówka tributary and second - as in variant I. The capacity of the reservoirs resulted from the anal-ysis of topographic maps and digital terrain model and the small retention program for the Malopolska Voivodeship. All calculations were carried out in the HEC-HMS. In the case of the analyzed catchment was the most preferred variant II. Calculations showed that this variant is possible to reduce the maximum flow by 50% compared to the variant with one reservoir, where the amount of reduction was less than 26%. In order to protect against floods in the Serafa catchment, de-spite higher capital costs should be considered a variant II with two tanks.