Quantitative evaluation of Kallar watershed using geospatial technology, Thiruvananthapuram, India

The composition of the stream system of a drainage basin is expressed quantitatively with stream order, drainage density, bifurcation ratio and stream length ratio (Horton, 1945). Watersheds are hydrologic units that are considered to be efficient and appropriate for assessment of available resources and subsequent planning and implementation of various development programs (K.V Seshagiri Rao, 2003). Using watershed as basic unit in morphometric analysis is the most logical choice because all hydrologic and geomorphic process occur within the watershed. The quantitative analysis of a drainage basin is an important aspect of studying the relief and relief characterization of watershed. The quantitative analyses of morphometric parameters is found to be of immense utility in river basin evaluation, watershed prioritization for soil and water conservation and natural resources management at watershed level. (M. Immam Malik et.al, 2011). Geospatial Information Technology (GIT) i.e. remote sensing coupled with Geographic Information System (GIS) is very useful in the delineation of drainage system characteristics. In the present study a detailed quantitative evaluation has been conducted in Kallar Watershed situated in the southernmost part of Kerala. In this basin, there are large numbers of drainage systems/channels originated from the Chemmunji Mottai (1717 M) the eastern side of Western Ghats mountain chain. The study performed manual and computerized delineation and drainage sampling which enables applying detailed morphological measures. Survey of India (1: 25, 000) topographical maps in combination with remotely sensed data were utilized to delineate the existing drainage system, thus to identify precisely water divides. The study introduces an imperial approach of morphometric analysis that can be utilized in different hydrological assessment (e.g surface water harvesting, flood mitigation) as well as the applied analysis using remote sensing and GIS in the rest of the drainage systems of the Kerala.