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Abstract
In many meteorological models the interface between atmosphere and soil surface is implemented as a lower boundary, but from a hydrological viewpoint this interface is the upper boundary. Complex processes occur at the surface and uncertainty in water and energy fluxes across the model boundaries are a source of model errors. Understanding and quantifying these fluxes can help to improve both meteorological and hydrological models.
Hydrologists often use water balances to determine the size of water fluxes across catchment boundaries. In this research a water balance is set up for a water system in Cabauw (Netherlands). The “catchment” of approximately 0.5 km2 is part of a polder area and is drained by small, man-made channels. The upper soil layer is heavy clay and covered with grass and maize. The area is flat and at an elevation of approximately one meter below sea level.
At the Cabauw experimental site for atmospheric research (CESAR) many meteorological quantities are measured. In addition to these measurements, the Hydrology and Quantitative Water Management Group of Wageningen University has installed weirs to measure discharges at the inlet and two outlets, ground water tubes and a TDR-system to measure soil moisture.
Precipitation and evapotranspiration data have been collected by the KNMI (Royal Netherlands Meteorological Institute) for more than 20 years. Ground water and soil moisture data are available since 2003, accurate discharge data since May 2007. A detailed development of the water balance terms in the period May 2007 – Jan 2009 will be presented on the poster.