Changes in land use and the growing number of flash floods in Germany

It seems that the frequency of floods along the main rivers in Germany increased during the second half of the past century. A number of causes for this phenomenon have been suggested. We hypothesise that postwar changes in agricultural land use also play a role. For example, the meadowland area in former West Germany decreased between 1951 and 1989 from 15.7 to 10.8%. Simultaneously, the small grain acreage grew from 18.5 to 22.3%. Additionally, nearly 20% of the agricultural land area was drained artificially during this period. We used the US Soil Conservation Service rainfall-runoff model for small drainage basins to estimate the possible increase in surface runoff during heavy rainstorms because of the observed changes in agricultural land use. Our model calculations suggest that increased surface runoff during large-scale heavy rainstorms may contribute substantially to the present flood problem in Germany.