Morphometric Analysis of a Vrishabavathi Sub-watershed Using Remote Sensing and Geographical Information System: A Case Study

Abstract

The seasonal abrupt flood event in the GaliAnjaneya Temple sub-watershed of Vrishabavathi watershed was the major loss for socio-economic infrastructure. The main objective of this study is to characterize the morphometric parameters of the nine micro-watersheds on the up-stream side of GaliAnjaneya Temple of Vrishabavathiv subwatershed, located at GaliAnjaneya temple of Bangalore city, Karnataka State, India, which depicted on topo sheets 57/H 9 and 57/H/ 9/1 with scale 1:25,000 were used. The morphometric parameters were delineated through STRM data using ArcGIS-10.1software. The sub- watershed is covering about 38.00 Km2 consists of valleys and plains. The longest flow path was calculated and found to be 9.311 Km. In this study, morphometric parameters such as stream length, bifurcation ratio, drainage density, stream frequency, texture ratio, form factor, circularity ratio, elongation ratio and compactness ratio are studied. The highest bifurcation ratio among all the micro-watersheds is 5.2 (3.647avg. for the entire sub-watershed) which indicates a strong structural control on the drainage. The maximum value of circularity ratio is 45.81for the micro-watershed No.5. The micro-watershed No.9 has the maximum elongation ratio of 1.041. The form factor values are in range of 0.113 to 0.850 which indicates that the Vrishabavathi sub-watershed has moderately high peak flow for shorter duration and has a dendritic drainage pattern.