The influence of Strzelin Quarry Lakes on small reservoir retention resources in the regional catchments

The paper presents the results of the analysis of the volume of water retained in Strzelin Quarry Lakes (SQLs). The volume of retained water was estimated by using the computational method, where the proposed reduction factors were determined with the use of DTM (digital terrain model). 2.6 hm(3) of water was retained in seventeen Strzelin Quarry Lakes, of which 1.2 hm(3) in the Ślęza River catchment (3 quarry lakes), and 1.4 hm(3) in the Oława River catchment (14 quarry lakes). The obtained data of the volume of water retained in SQLs were compared to the balance of the water retention capacity of water reservoirs in the catchments of the Ślęza River (0.809 hm(3)), part of the WR08 Bystrzyca balance catchments (16.190 hm(3)) and in the catchments of the Oława River (2.782 hm(3)), part of the WR09 Nysa Kłodzka balance catchment (104.960 hm(3)). Inclusion the volume of water retained in Strzelin Quarry Lakes in the small scale water retention (reservoirs and ponds) balance would increase the volume of retained water by 156.0% in the Ślęza catchment (by 7.8% in the WR08 Bystrzyca balance catchment) and by 49.5% in the Oława catchment (by 1,3% in the WR09 Nysa Kłodzka balance catchment). Under favorable hydrogeological and geomorphological conditions water reclamation of the excavations may be one of the main aspects of increasing the retention capacity of the catchment, what is particularly important in areas characterized by low water resources.