Influence of agricultural activities on formation of the water flow of Samara River in 1936-2020

Abstract

Agricultural lands occupy 90% of the Southern Urals. The influence of agricultural activity on the catchment area and changes in it on the runoff of melt water from the catchment areas of its steppe zone in 1936-2020 years is considered. on the example of the unregulated upper reaches of the Samara River. In the pre-war 1936-1941 years in the grass-field system of agriculture, with an increased density of soils under perennial grasses, half of the melt water entered the rivers. During the war years, with the deterioration of the culture of agriculture, the runoff coefficient increased to 0.7. After the war, with an increase in the area of arable land and the transition to autumn plowing, the retention of melt water in the fields increased with a corresponding decrease in the runoff coefficient to 0.35. Slightly changing farming system 1966-1990 years the runoff coefficient has been stabilized at an average of 0.29. Frequent land-use changes 1990-2020 years led to an unstable flow regime of melt water. The total runoff of melt water from the catchment area is determined by the ratio of its lands with different filtration coefficients of frozen soils. A method is proposed for determining in the laboratory the rate of absorption into frozen monoliths, depending on the temperature and moisture content of the soil, and its definitions are presented for the main lands of the steppe zone.