Distribution of soil moisture and groundwater levels at patch and catchment scales

This study is a contribution to the northern hemisphere climate processes l and surface experiment (NOPEX). Its purpose is to investigate the spatial v ariability of groundwater levels and soil moisture content at different sca les in a landscape dominated by boreal forest and till soils, which is char acteristic of the Nordic countries. The analysis of data from the NOPEX are a are based on a review of previous studies on the spatial distribution of these state variables and their significance for runoff formation. Soil moi sture content in the unsaturated zone and depth to the groundwater table sh ow characteristic patterns which are related to the landscape elements (pat ches) of the drainage basins. Similar behaviour is observed in different pa rts of the NOPEX region. The variability of average values between areas de creases to a minimum for catchments with size larger than 1 km(2). It can t herefore be concluded that the main part of the spatial variability of soil moisture content and depth to the groundwater level in the till soils of t he NOPEX area is found within small drainage basins. Based on a physical de scription of the soil, distribution functions of soil moisture content cond itioned on the depth to the groundwater table have been developed, both for the patch scale and the catchment scale. (C) 1999 Elsevier Science B.V. Al l rights reserved.