FACTORS OF FLOOD HAZARD OF RIVERS OF THE NORTH-WEST CAUCASUS

The paper is devoted to assessing the flood hazard of river catchments in the North-West Caucasus based on the distribution of water-regulating properties in the catchments of the main river systems. The distribution of vegetation and soil cover in the study area is considered and their water-regulating properties are evaluated. Heterogeneity of soils and vegetation leads to significant variability in the space of drainage and water-retaining properties of catchments. In the conditions of sufficiently well-studied soils of the North-West Caucasus, their granulometric composition and drainage properties, and as a result, the hydrological role in general, it is necessary to conduct additional research on the influence of forests on the conversion of precipitation into runoff. The article describes the influence of morphometric characteristics of watersheds on the formation of flood runoff. Generalizations of the influence of flood-forming properties of catchments are made, and a method for comparing the flood hazard of catchments with each other is proposed based on spatial analysis in a geoinformation system. Based on the estimates of run-off rates and the analysis of digital terrain models, histograms of the distribution of areas in the catchment area by the time of run-off from them to the closing gate were calculated, and hydrographs for the closing gates of the selected catchments were calculated on the basis of histograms. As a result of the research, it was found that all the studied catchments are divided into catchments with one peak of expenditure and several ones. In this case the single peak of the watershed, tend to have a smaller area, and consequently a more simple structure. They have a direct relationship between the area and the maximum flow rate, as well as the area and time between the maximum precipitation and expenditure. The time dependence between maximum precipitation and maximum expenditure is weakly expressed in both single-peak and multi-peak catchments, and even the reverse relationship is observed in multi-peak catchments of the southern macro-slope.

North-West Caucasus, rainfall flood, flood risk, vegetation of the Caucasus, flash flood