Sub-watershed Prioritization Based on Drainage Morphometric Analysis: A Case Study of Cauvery River Basin in South India

Prioritization of sub-watersheds in a river basin using morphometric parameters is one of the simplest approaches for development of watersheds for its use and management. In this perspective, a study has been undertaken in the Cauvery river basin in South India, using morphometric analysis of the entire river basin in relation to its 17 sixth order sub-watersheds. In this study, automated extraction of drainage network method was applied using geospatial techniques. Drainage morphometric analysis was performed through linear, aerial and relief aspects. Strahler stream order classification was applied for classifying the stream order. In general, dendritic and sub-dendritic types of drainage patterns are noticed in the Cauvery river basin. The total length of the river and basin area are 800 km and 82283 km(2), respectively. Hypsometric analysis reveals that about 30% of the study area is covered by steep slope with deeply dissected landscapes and the remaining 70% spreads essentially in the Mysore plateau and Tamil Nadu plains which are generally having gentle slopes with an equilibrium stage of landscape development. Prioritization of sub-watershed was carried out based on compound parameter analysis by adding the values of linear and shape parameters of each sub-watershed. The results of prioritization of sub-watersheds reveal that about 88% of sub-watersheds that spread in the river basin fall under high and moderate priority categories for water resource developments. Only two sub-watersheds fall under the low priority category which in turn are safe in the case of water resource development. The study warrants the need for more focused investigations and corrective measures including construction of appropriate recharge structures for improving the water potential of the river basin.