GIS Based Morphometric Analysis of the Kochara Sub-Watershed of Greater Periyar Plateau (GPP) of South Western Ghats, India

Abstract

The Munnar Plateau and the Greater Periyar Plateau (GPP is composed of Periyar and Pirmed plateaus) of the South Western Ghats of India had their origin during the Late Palaeocene and it has been assessed that the deduced age of these plateaus coincides with that of the Biligirangan surface. Ever since their formation, both the plateaus have been subjected to substantial geological modifications during the subsequent years, especially the Periyar plateau of the GPP, which was acted as Holocene depocentre. The distribution of palaeodeposit of sand in the Kochara sub-watershed occupying the Periyar Plateau of the South Western Ghats has led to interpret the quantitative geomorphology of the river basin for elucidating the relationship between mathematical expressions and filed observations. 163.07km² basin area of the Kochara stream was subjected to morphometric analysis. The drainage networks were delineated using remote sensing data – Geocoded False Colour Composite (FCC) of IRS 1D (LISS III) coupled with the Survey of India toposheets (1:50,000) and the morphometric analysis was carried out using ArcGIS software. Linear aspects, relief aspect and aerial aspects of the basin were analysed and the relationships among the different aspects were interpreted. The study depicts the remarkable relationship between theoretical data sets with field observations, especially the role of geology, geomorphology and tectonism in influencing the basin morphometry and identity. Hence, the analysis of the inter-relationships among the basin parameters helps in understanding the terrain characteristics, slope, landforms, soils, soil erosion and ground water potential for watershed development and management.