The impact of geological on density of the river system in Timok river basin

Abstract

The density of the river system is one of the very important factors pertaining to precipitation drain out from the river basin. Its extent depends mostly on the geological composition, precipitation, relief characteristic and surface under forests. Since there was no study of the relation between the type of rock and density of the river system, density of the river system in the Timok river basin has been calculated for all dominant litological foundations, both that for the permanent flows and total density (permanent + periodical). For that purpose the Timok river basin was divided into seven sections so that the results might be compared. Because of the similarity in density for various groups of rocks, they were classifed into 6 categories: alluvium, limestone, sedimentation rocks (without limestone), metamorphites and magmatites. For waterproof rocks it was established that density of the river system for permanent flows has approximate value (550 m/km2), but taking into consideration periodical flows, it was highest in magmatic rocks (1293 m/km2). The least density of the river system showed the permanent flows on limestone (248 m/km2). The general conclusion is that such obtained results cannot be neither transposed to other territories, nor declared typical, for the simple reason that in the very Timok basin they are not identical. This difference is mostly affected by. the unequal precipitation in the river basin as well as relief contrasts (related to the precipitation drain out). In the previous works determing density of the river basin there was a big mistake caused by the fact that measurement were done on maps on scale 1:100,000. In such maps there are no periodical flows. Length of permanent rivers is shortened (because of the contents generalization), any mayn seasonal flows are designated as permanent flows. Utilization of topographic and geological maps on scale 1:25,000 in the Timok river basin revealed mistake in establishment of the river basin density of 32-167 %, caused by utilization of maps on a lower scale.