Using the SWAT model to characterise the water regime of soils in agrolandscapes

Abstract

The classification of soils water regimes a basic scientific basis in the form of an interdependent relationship between the movement of water and the formation of a soil profile, i. e. it is soil-genetic classification. This kind of classification provides a scientific and methodological platform for studying both the water regimes of soils in the landscape and the distribution of soils in the soil cover of the landscape. Numerical methods for representing the hydrological regimes of soils in the agricultural landscape are based on physically validated mathematical models of the soil water movement and spatial GIS information, which together allow to calculate, analyze and predict soil water regime, runoff in the scale of watersheds, substance transport in the soil profile, leaching processes, as well as the content of available soil moisture reserves in the agrolandscape structure – which is important for practice. A spatial-dynamic SWAT (Soil-Water-Atmosphere-Tool) model is presented to describe the water regimes of soils in the agro-landscape of the finite moraine ridge of the Upper Volga postglacial region (East European Plain, Tver region), as an example of landscape numerical hydrological models. Some examples are given in the article, which demonstrate that modeled data correspond well with experimental data on soil moisture dynamics in several points of agrolandscape for 3 depth levels, reflecting surface, deep (at groundwater level) and middle layers of soil profile, i. e. 10–20, 50–60 and 90–100 cm. On the one hand, the data were obtained by calculations with the help of the considered landscape-dynamic model; and on the other hand, – by classical soil drilling, sampling and gravimetric method for soil moisture content determination. It has been shown that the landscape model, adapted for specific conditions, using a digital elevation model with a resolution of 1×1 m per pixel, to calculate the soil water regime at different points of the agrolandscape satisfactorily describes the spatial-dynamic profile data on soil moisture.