USE OF GIS FOR WATER RESOURCE DEVELOPMENT

Abstract

The present study has been carried out to prioritize watershed using morphometric parameters in ARC GIS environment. This study has been carried out for watershed of Ret river encompassing an area of about 262 km2. The watershed of Ret river was further delineated into 26 subwatershed. A Digital Elevation Model (DEM) was developed with a contour interval of 20 m in using ARC GIS. Various morphometric parameters were derived for each of the above subwatersheds using Geographic Information System (GIS). Morphometric parameter includes bifurcation ratio, form factor, circularity ratio, elongation ratio, drainage density, stream frequency, drainage texture. Watershed prioritization and water resource development plan were derived by integrating remote sensing based land use/cover, soil and slope information with morphological parameters under ARC GIS environment. The highest value of bifurcation ratio, drainage density, stream frequency, drainage texture among 26 subwatersheds was assigned a rating of 1, the next highest values was given rating of 2, and so on. For the shape parameters i.e. form factor, circularity ratio, elongation ratio, the lowest value was given a rating of 1, and the next Iowest value was given a rating of 2, and so on. Integration of the above seven parameters was done using simple summation of ratings. Based on the average value of these parameters, the subwatershed having the least rating value was assigned the highest priority number of 1, the next highest value was assigned a priority number 2, and so on. Based on the average value of these parameters, the subwatershed having the least rating value was assigned the highest priority and vice versa. Finally, the subwatersheds were classified into the five scales of priority, namely: very high, high, medium, low and very low category. Among the identified subwatersheds in the Ret, six subwatersheds covering an area of 66.5 km2 falls under very high category. The count of subwatersheds which fall under high, medium, low and very low priority class are five each and covering areas of 61.7, 58.27, 39.62 and 31.84 km2 respectively.' Based on stream order, average slope, land use/land cover, soil type of the subwatersheds, suitable sites for check dams were identified and marked in the drainage map for very high, high, medium, low and very low priority areas of Ret watershed. In view of the requirement of soil and water conservation measures, it has been proposed to construct check dams in subwatershed no. 1, 4, 5, 6, 7, 8, 9, 10, 12, 22, and 24. For the design of check dams, surface water potential and peak rate of runoff was estimated using CN method and rational method respectively. Design " of check dam has been carried out for the subwatershed no. 1 (medium priority) and 4 (very high priority). The design dimensions of crest level of the weir, pond level, and top bank level are 622.8, 624 and 625 m respectively for the subwatershed no. 1. Similarly, for subwatershed no.4, the corresponding dimensions are found to be 601.8, 603 and 604 m respectively. Construction of proposed check dams in the watershed will ensure crop production in Kharif season