Hydrological importance of carp ponds in the upper Vistula River catchment basin

Apart from their basic role as fish farming reservoirs, carp ponds have an important influence on water circulation and thus on water resources in the catchment basin. The positive influence of carp ponds as storage reservoirs results from the rearing cycle which corresponds with the hydrological cycle and consists in limiting high water-flows in the summer and increasing low water-flows in the autumn. After the maximum precipitation shifted in the late 1960s from summer months to autumn months, a dramatically low water level occurred in the summer. This highly disturbed the catchment basins’ hydrological balance as well as the ponds’ water management. The influence of the changing meteorological conditions on individual components of the water balance are presented as a result of many years’ research (1957-1997) conducted at the Institute of Ichtyobiology and Aquaculture of the Polish Academy of Sciences in Gołysz.