The evaluation of Morphmetric characteristics of Upper Subarnarekha Watershed drainage basin using Geoinformatics as a tool, Ranchi, Jharkhand

The development of Morphometric techniques was a major advance in the quantitative description of the geometry of the drainage basins and its network which helps in characterizing the drainage network, comparing the characteristic of several drainage networks and examining the effect of variables such as lithology, rock structure, rainfall etc. The geographical position of watershed is 85° 10′0" to 85° 40′0"E and 23° 10′0" to 23° 40′0" N. The elevation of the watershed ranges from 300m to 700m within Ranchi district. The study was carried out using the method of Horton and Strahler, to rank the stream segments using ArcGIS 9.2. The relevant numbers of the streams were entered into the attribute table and all other analyses based on the mathematical formulas. The results indicated that the watershed area was 594.68 km², perimeter 159.26km, mean slope 32.21, axial length 54.70 km, basin width 23.61 km, form factor 0.20, compactness factor 1.40, circulatory ratio 0.29, elongation ratio 0.50, number of segments was 935 of each order those varied 1 to 6th. The stream frequency and drainage density were 1.57 (No./km²) and 1.12(km/km²). Bifurcation ratio and length of overland flow were 3.94 and 0.56 km. The results of this analysis would be useful in determining the effect of watershed characteristics such as size, shape, slope of the watershed & distribution of stream net work within the watershed.