SOIL-WATER BEHAVIOR IN A PUSH TERMINAL-MORAINE, COMPARISON OF ONE-DIMENSIONAL AND 2-DIMENSIONAL SIMULATIONS BASED ON INTENSIVE REGIONAL FIELD OBSERVATIONS

To predict the contamination risk of drinking water in a water catchme nt, regionalization methods, in which regional transferability is pres upposed by assigning areas of same qualities, are used. Those methods use soil information at the field scale to build up soil profiles, whi ch serve as input for one-dimensional simulation models of water and s olute transport together with management data. These simulation models compute groundwater recharge to determine the transport and contamina tion risk of solutes. The regionalization method assumes horizontal ho mogeneity and one representative soil profile (principal profile) for each soil mapping unit. Our objective is to show that those regionaliz ation methods have to be improved in regions of high spatial variabili ty of soil qualities. As an example we examine a terminal moraine typi cal of northern Germany. We combine intensive investigations of the so il structure, long-time field observations and simulation results to s how the necessity to improve methods for soil mappings. Our results su ggest that it is necessary to perform higher-dimensional simulations o f water and solute transport in regions of high spatial soil structure variability. Two-dimensional simulations compute earlier and higher g roundwater recharge rates than one-dimensional simulations.