Assessing spatial soil moisture patterns at a small agricultural catchment

Abstract

A good understanding of soil moisture spatial patterns is useful for assessing the hydrological connectivity and runoff generation processes in a catchment. Thus, we have applied numerical modelling approaches to investigate the spatial patterns of soil moisture at the Nučice experimental catchment (0.531 km2) in the Czech Republic. The catchment was established in 2011 to observe the rainfall-runoff processes, soil erosion and water balance in an agricultural landscape. The catchment consists of three fields covering over 95 % of the area. Eight field surveys were conducted to capture the soil moisture patterns at different scales. Even though the soil management and soil properties in the fields of Nučice seem to be nearly homogeneous, we have observed spatial variability in topsoil moisture. In numerical simulations, a 3D spatially-distributed model MIKE-SHE was used to simulate the water movement within the catchments. The MIKE-SHE simulation has been mainly calibrated with rainfall-runoff observations and point-scale soil moisture data. In the simulation, we have obtained the spatial patterns of soil moisture at each time step. The soil moisture spatial patterns from the simulation have been compared with the density of the vegetation cover (NDVI), and topsoil moisture patterns from field surveys. We found that the density of vegetation cover has a good correlation with the soil moisture spatial distribution. However, this correlation was not captured in the MIKE-SHE simulation. Future research will include Cosmic-ray neutron sensing and stable isotope analysis to improve the current understanding of the catchment.