Runoff Changes in the umava Mountains (Black Forest) and the Foothill Regions: Extent of Influence by Human Impact and Climate Change

The main aim of our research project was to determine the extent to which the outflow can be influenced by human interventions in three selected water basins in the umava Mountains (Black Forest) and its foothills. The rainfall-runoff analyses using both the single-mass and double-mass curves over the period of hydrologic observations were taken as a preliminary methodology. Standard statistical testing methods Wilcoxon and Mann-Kendall non-parametric tests were applied to detect the trends. Besides mean discharge, precipitation, snow and air temperature trends, analysis of land cover change and human impact on the river network and development of drainage areas were also carried out. The greatest deviations were widely observed in the period between the second half of the 1970s and the first half of the 1980s. The whole system came slowly back to its initial condition in the early 1990s. The runoff trend deviation was related to natural and human factors, mainly to current climatic changes, river network modification and changes of land cover.