it is also an important winter roosting place for many birds especially geese the construction of the nove mlyny reservoirs on the dyje river intended to provide flood retention and a possibility to enhance low flow during droughts changed the character of the river below the reservoir and besides other changes reduced spring floods of the neighbouring floodplain the most negative impact of river regulation works is nowadays the dredging of the riverbed causing disconnection of the riverfloodplain system decrease of the water table and potentially threatening groundwater sources