The influence of historic land use changes and future planned land use scenarios on floods in the Oder catchment

In July 1997, dramatic flooding occurred in the Oder Basin, covering parts of the Czech Republic, Poland, and Germany. In August 2001, Poland again suffered from flooding, but more in the Vistula River than in the Oder River. To investigate the causes of the flooding and the influence of land use, soil characteristics and antecedent catchment moisture conditions, the distributed catchment model LISFLOOD has been developed. LISFLOOD simulates runoff in large river basins. In close cooperation with the water authorities of Germany, Poland, and the Czech Republic, the model has been set up, calibrated, and validated for the flood events of 1977, 1985, and 1997. Several scenarios have been evaluated with LISFLOOD, such as the effects of flood defence measures and also of expected future trends of climate and land use change. The study has demonstrated that the proposed measures for flood control by the International Oder Commission lead to a significant improvement and reduction of flood risk in the Oder catchment, especially for downstream reaches. Historic land use changes show an increase in forested and urban areas between 1780 and 1995, which hydrologically are balancing out each other in terms of discharge. It has been shown that the use of flood forecasting in reservoir management can also reduce flood risk downstream. Finally, it is expected that urban growth will slightly increase flood risk in the next 30 years.