Water Balance and Climatic Classification of the Cauvery River Basin, India

The Cauvery basin covering an area of about 81, 155 km2 has been studied with view to explain the spatial distribution of water balance elements like potential evapotranspiration, actual evapotranspiration, water deficit, water surplus, moisture adequacy, Aridity Index and Moisture Index. From about 37 stations the mean monthly rainfall and mean monthly temperature is collected over a period of fifty years. Applying Thornthwaite and Mather (1955) book keeping procedure the monthly, seasonal and annual water balance elements of the Cauvery basin are worked out and mapped. The annual recharge of the Cauvery basin has been worked out using rainfall recharge method. From the analysis it is found that the Western Ghats, Nilagiris and Kodaikanal hills of the Cauvery basin experiences water surplus. The central and eastern plains of the basin experience water deficit. From the analysis of water balance it is found that out of total surface water resources of 105, 109, 725, 000 m3 about 10 % is stored in surface tanks, ponds and reservoirs, 15.06 % is recharged to ground water, 30 % is lost in the form of surface run-off and 44.94 % of the water is lost in the form of evaporation and evapotranspiration. The Western Ghats, Nilagiris and Kodaikanal hills experience to per humid and humid type of climate. The Mysore plateau region experiences wet sub humid and dry sub humid types of climate. The central and eastern plains of the Cauvery basin experience dry sub humid type of climate.