Assessment of Diffuse Runoff Formation Using Geoinformation Technologies

The paper considers the main causes of the bloom of freshwater objects, the scale of the phenomenon in the world, and its toxicity and negative consequences for aquatic ecosystems. It is noted that in agricultural regions, eutrophication of water bodies proceeds faster due to the diffuse supply of nutrients from plowed areas. The research aims to develop a methodology for assessing the volume of pollutants entering the river network and receiving reservoir from agricultural lands of the watershed. Remote sensing data, cartographic materials, and scientific reference materials are used as information sources. The work has been done in the ArcGIS Pro program, which has allowed completing the tasks set in the research. The research has been conducted in Russia on the example of the watershed of the right lateral tributary of the Tsimlyansk reservoir—the Tsimla River. The methodology includes the following main stages: (1) studying the current state of the river watershed; (2) identifying and differentiating arable land according to the use and the degree of development of erosion processes; (3) determining the percentage ratio of land for various purposes; (4) constructing a map of slope angles according to a digital elevation model of the watershed area; (5) determining the assignment of arable land to areas with different terrain slopes; and (6) calculating the runoff volume of fine earth and pollutants from plowed areas by melted snow and rain waters for the year according to expert estimates. As a research result, a series of basic and thematic maps have been developed, the necessary calculations have been made, and diagrams and tables have been built. The significance and novelty of the conducted research lie in the possibility of obtaining estimates on the volume of pollutant runoff from arable land (in the first approximation) under conditions of a shortage of ground-based observations since hydrological and hydrochemical surveys are practically not performed on small rivers. Increasing the accuracy of the expert estimates used and obtaining additional information about climatic conditions and the amount of fertilizers applied will also contribute to improving the accuracy of the calculations. The methodology can be used for other water bodies and their watersheds.