Modelling hydrologic regime of Lakshmanatirtha watershed, Cauvery river

Basic amenities such as clean water, air and food are essential not only for human livelihood but also for the surrounding biotic habitats in the environment for sustainable development. Due to the human habitation, and the anthropogenic activities, large scale change in land use has affected the hydrologic regime across watersheds. The water resource availability in a catchment depends upon the integrity of the land use, terrain and meteorological parameters such as rainfall, temperature, etc. The land use of the catchment plays an important role in maintaining the water flow in the rivers or streams as either surface or subsurface runoff (Pipeflow and Baseflow), holding water in the sub strata´s, recharging the aquifers and hence catering the water demands as per the human and environmental needs. The study was conducted in order to understand the dynamics of land use and its implication on the catchment capabilities in catering the demands of environment (forests), agriculture, domestic and livestock needs on Lakshmanatirtha catchment of the Cauvery river basin which has an area of 3969 km². The land use assessment using remote sensing and GIS showed the catchment is dominated (61.94%) by agriculture and horticulture, followed by forests with as area of 14.3% followed by other land uses. The Ghats (uplands) of the catchment is dominated by forests where as the plains are with agriculture and horticulture activities. Hydrologic assessment is done using the land use and the meteorological data was carried out at watershed level. The assessment showed that out of five watersheds, four of the watersheds had very high deficiency of water for over 3 months, and one of the watersheds had no deficit. The deficiency of water indicated that the watersheds were not able cater the both the human and environmental needs but also the streams were devoid of water flow which explains the deficiency in maintaining ecological flow.