Geodesy, Cartography, and Aerial Photography

Abstract

Aim of the work. To develop a method of automated allocation of catchment basins and obtaining their hydrological and morphometric characteristics, which is based on digital terrain models. Methods and results of work. A necessary condition for the correct filling of the terrain is the presence of points of true flow at the edge of the settlement area (if the river flows into the lake, it should not enter the calculated area completely, otherwise incorrect results will be obtained). By performing the operation of filling the relief of the terrain, a new dem is created, which does not contain fictitious depressions and is used in the next step as input data to calculate the flow direction according to the algorithm d8. According to the proposed technological scheme it is necessary to process step by step the following six blocks: filling of closed depressions, calculation of runoff direction, calculation of total runoff, creation of point vector data set of closing points (mouth points), creation of watershed boundaries, raster-vector data conversion. Theoretical research tested the method of automated allocation of watersheds, namely the determination of hydrological and morphometric parameters of the terrain. The pools were ranked according to these parameters according to the existing classifications, a series of relevant thematic electronic maps was compiled. It should be noted that in Skole district of lviv region there are 590 catchment areas, and their area is 1407 km2. Watersheds are classified by outcrop, namely low-mountain basins in the region of 6, their area is 7 km2, medium-mountain 360, area 755 km2, high-mountain 224, area 645 km2. Pools are classified according to the average slope: the first category from 0-3 degrees, very gentle slopes - pools 27, area 7 km2; the second category from 9-12 degrees, sloping slopes-pools of 128, the area 303 km2; the third category from 12-15> degrees, steep slopes - pools of 225, the area 648 km2. The accuracy between the reference and the original relief model was evaluated. We can say that sle = 0.63 (m) slope, sle = 5.43 (m) height. Scientific novelty and practical significance. The technological scheme of automated separation of catchment basins according to digital relief models for Skoliv district of lviv region is proposed and the method of separation of catchment basins is worked out. According to the developed method, maps of watercourses of different orders and their catchment basins and classification of basins by area on the territory of Skole administrative district, which can be used by local organizations on water resources, are constructed.