Geospatial approach to elucidate anomalies in the hierarchical organization of drainage network in Kuttiyadi River Basin, Southern India

An assessment of anomalies in the hierarchical organization of the drainage network in the Kuttiyadi River Basin (KuRB), Kerala, has been performed by considering various morphometric parameters such as bifurcation index (R), hierarchical anomaly index ( increment a), hierarchical anomaly density (ga), and stream gradient index (SL) in a geographical information system (GIS) platform. Further, a digital elevation model (DEM) of the area has been generated from Cartosat stereo pair data at 2.5-m resolution. The computed quantitative information about drainage characteristics reveals the highest drainage anomaly is observed in sub-watersheds (SW) III and IV. It is observed that neo-tectonic activity caused the development of younger stage drainage patterns of structural controls in the sub-watersheds of this river basin. The tectonic activity-induced diffusion, high energy fluvial erosion, and anthropogenic interferences altered the hierarchical organization of the drainage network of the sub-watersheds in mature to old stages of geomorphic evolution. The results of finding validated with asymmetry factor and ratio of the hierarchical index ( increment a) with hierarchical anomaly number (A), bifurcation index (R), direct bifurcation ratio (R-db), stream gradient index (SL), and denudation index (logTu). From the denudation index analysis, the sediment yield of the river basin is identified as 0.67 t center dot km(-2)center dot yr(-1). Moreover, the asymmetric factor (AF) in the KuRB shows the imprints of Paleo-Neo Proterozoic crustal tilting toward a NNW-SSE direction.

Automated summary

This study assesses anomalies in the hierarchical organization of the drainage network in the Kuttiyadi River Basin using various morphometric parameters and a geographical information system platform. It is found that the sub-watersheds in this river basin experience the highest drainage anomaly, which can be attributed to neo-tectonic activity, high energy fluvial erosion, and anthropogenic interferences.