Hierarchical anomalies in drainage network: a case study from Western Ghats, South India

Abstract

The Chalakudy river, a seventh order tropical drainage system emerging from the Western Ghats is flowing through the Southern Granulite Terrain of Peninsular India. Anomalies in the hierarchical organization of drainage networks reflect the effects of anthropogenic interferences and structural controls in the development of a drainage basin. The anomalies in the drainage composition are determined from bifurcation index, hierarchical parameters and stream gradient index. Computation of drainage indices is carried out with the aid of vectorized data derived from Survey of India (SOI) open series topo maps and Shuttle Radar Topographic Mission (SRTM) data (3Arc resolution) using ArcGIS 10.4 software. Here we discuss the quantitative methodology to determine the hierarchical anomaly index, hierarchical anomaly density and hierarchical anomaly number of drainage basin from geospatial data with an attempt to infer the degree of geomorphic evolution of the sub-basins from the analysis. The sub-basins are in their mature to the late mature stages of geomorphic evolution. It is observed that the tectonically induced diffusive process and anthropogenic interferences in the drainage basin altered the hierarchical organization of drainage network of Chalakudy river basin.