Spatially distributed assessment and forecast of soil erosion losses as a basis for optimization the use of erosion-hazardous agricultural lands

The article is devoted to the problem of sustainable use of agricultural lands in conditions of active manifestation of water soil erosion, which is typical for all natural zones of Ukraine, but to the greatest extent – for the Forest-Steppe and Steppe zone. The aim of the article is a spatially distributed quantitative assessment and forecast of soil erosion losses and the development on this basis of recommendations to optimize the use of agricultural land on the example of the Pidhayetskyi district of the Ternopil region. The area is located within the Western region of Ukraine with a fairly high intensity of water erosion, where in accordance with the long-term climate forecast a further increase in erosion hazard of land is expected. A quantitative assessment of soil erosion losses for the basic period (1961–1990) and forecast periods (2031–2050 and 2081–2100) was carried out using a spatially distributed physical-statistical GIS-model of soil erosion-sedimentation developed at the Department of Physical Geography, Nature Management and Geoinformation Technologies of Odesa I. I. Mechnikov National University. Spatial realization of the model performed using the analytical capabilities of the Software for Environmental Modeling PCRaster (University of Utrecht, Netherlands). The forecast of the changes in the hydrometeorological conditions of water soil erosion was made using the forecast of monthly average air temperatures and monthly average precipitation, developed at the Ukrainian Hydrometeorological Institute. It established that most of the arable land (about 52 %) of Pidhayetskyi district is erosively dangerous. Due to the projected increase in summer rainfall in the middle and at the end of this century, further intensification of soil erosion is expected, especially in 2031–2050, when soil losses on arable land will increase to 16.9 t/ha/year, and only due to rainstorm erosion. Soil losses by meltwater will be insignificant. Based on the calculations, it was concluded that it is impossible to protect the agricultural lands of the region from erosional degradation without withdrawal from the arable land about 8.15 thousand hectares (28) of the most erosion-hazardous lands (with annual soil losses exceeding 20 tons per a hectare), changing the structure of sown areas and introduction a soil-protective adaptive-landscape farming system over a significant area.