Simulation of Groundwater Formation on the Sand Massifs of the Don Region: The Case of the Eterevsky Sand Massif

Abstract—This study investigated the effects of hydrological, agroecological, and soil-hydrophysical factors on the vertical subsurface flow within the vadose zone and groundwater (GW) recharge on the sand massifs in the Don Region. This involves issues of adapting lysimeter studies to field observations in investigations of the moisture transport dynamics in light-textured soils. Techniques for reconstruction of the main hydrophysical characteristics and the scaling were employed to simulate moisture transport under various initial and boundary conditions. Laboratory investigations were performed at the Hydrological Complex of the Federal Scientific Centre of Agroecology of the Russian Academy of Sciences; field studies were conducted on the Eterevsky sand massif in Volgograd Oblast. The reconstructed hydrophysical parameters and HYDRUS-1D program revealed the effects of different soil–plant conditions on GW recharge. The open sands have an inflow to GW throughout the year, which ensures a stable supply to the river systems. The grounds occupied by herbaceous plants and pine plantations on soils with low water holding capacity, are the supplementary source of GW recharge. The volume of the gravity flow from the vadose zone to GW was established to depend entirely on the biomass of the herbaceous plants on the sands and the quality (bonitet) of the forest plantations.