Hypsometry and Geomorphic Development of a Watershed: A Case Study from South India

Hypsometric analysis is useful for understanding the stages of geomorphic development of a river basin. Hypsometric integral quantifies the geologic stages of development and erosional proneness of the watershed. In this study, efforts were made to estimate the hypsometric integral values of the Chalakudy river basin located in Kerala state of south India. River basin was delineated into five sub watersheds and hypsometric analysis was carried out for all of them by using the 30 m ASTER DEM. Elevation, relief ratio method was also used for calculation of hypsometric integral values. The hypsometric integral values of all the sub watersheds of Chalakudy watershed ranges between 44 to 62 %. In the study area, two stages of erosional cycle development namely youthful to mature stage are identified. The development of stream segment is effected by slope and local relief. These factors produce differences in values of drainage density among the sub basins. The morphometric parameters such as drainage density and constant channel maintenance were also computed and relative extent of erosion in different subbasins is estimated. The values of geomorphic aspects were in agreement with hypsometric integral values. An attempt is also made to examine the effect of lithological characteristics on the denudation process in different subbasins. The estimation of erosion status of sub basins helps in the water shed prioritization for taking up soil and water conservation measures in watershed systems.