Hydrological conditions of geomorphologic changes in the gap of the vistula between Zawichost and Pu … awy

The Vistula is a river where natural flood hazard lasts all year round. Floods in the middle and lower courses of the river occur in summer. It is caused by heavy precipitation in the upper part of the drainage basin. Water levels of the Vistula recorded during the flood in July 1997 reached maximum values, higher even than in the years 1921 - 1990. The processes of surface water run off to underground water that decreased the maximum flow values, and flood capacity was observed. It decreased the amount of drift load which was brought to a stop at the valley floor. At the same time, the river channel floor of medium and low water levels was getting low. All the processes in the river channel are caused by natural reasons remain under very strong anthropopression.