Soils store infiltrating water as a result of capillary forces. Soil water storage is a key element in the hydrological cycle as it provides a storage for evapotranspiration and controls important hydrological functions such as runoff production and evapotranspiration as a function of soil moisture. Finally, percolation, the downward movement of water depends on the soil water status, the soil water contentm. Percolation that reaches groundwater is termed groundwater recharge and is an important parameter for the sustainable use of groundwater.The soil water content can be measured with soil moisture sensors. These sensors measure indirectly the amount of water stored in the soil.
During summer months in northern and central Europe soil moisture levels drop as a result of depletion by evapotranspiration. At a residual water content evapotranspiration and percolation stop and capillary forces prevent further depletion. The residual water content, also called water content at wilting point, depends on the soil type. We measure soil moisture at two stations in Lübeck and at several depths: One station is located at the TH Lübeck Campus on sandy soil, one stations is located on marly soil.