The heterogeneity of runoff and its significance for water quality problems

Abstract

Abstract In a small heterogeneous limestone basin with mixed land use twelve flow components were distinguished by using chemographs of flood events and baseflow. Only a few of them are endmembers. The number of flow components depends on the tracers that are used and on the degree of heterogeneity. If the concept of flow components is restricted to endmembers only, the runoff generation process cannot be explained completely because runoff does not form by the mixing of chemically distinct water types alone. Beside water types, there are all kinds of temporal variations ranging from steep gradients to continuous changing, e.g. due to incomplete mixing, exhaustion of sources, etc. This means that the original concept of flow components should be extended to behaviour patterns in order to obtain a basic understanding of the very complex process of runoff generation. Furthermore it is an excellent approach to facilitate understanding of the temporal variation of water quality in flowing waters.