ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture 169 IMPACT OF CLIMATE CHANGE ON RUNOFF OF THE MAJOR RIVER BASINS OF INDIA USING GLOBAL CIRCULATION MODEL (HADCM3) PROJECTED DATA

The effects of climate change on hydrological regimes have become a priority area for water and catchment management strategies. The terrestrial hydrology driven by monsoon rainfall plays a crucial role in shaping the agriculture, surface and ground water scenario in India. Thus, it is imperative to assess the impact of the changing climatic scenario projected under various climate change scenario towards the hydrological aspects for India. Runoff is one of the key parameters used as an indicator of hydrological process. A study was taken up to analyse the climate change impact on the runoff of river basins of India. The Global Circulation Model (GCM) output of Hadley centre (HADCM3) projected climate change data was used. Scenario for 2080 (A2 scenario indicating more industrial growth) was selected. The runoff was modeled using the Curve Number (CN) method in spatial domain using satellite derived current Landuse/cover map. The derived runoff was compared with the runoff using normal climatic data (1951-1980). The results showed that there is a decline in the future climatic runoff in most of the river basins of India compared to normal climatic runoff. However, significant reduction was observed for the river basins in the eastern region viz: lower part of Ganga, Bahamani-Baitrani, Subarnrekha and upper parts of the Mahanadi. The mean runoff reduction during 4 months (JuneSeptember) were 66 mm, 110 mm, 120 mm and 113 mm for Brahmaputra-Barak Subarnrekha, Subarnarekha and Brahmini-Baitrani basin, respectively in comparison to normal climatic runoff. Overall seasonal (June to September) runoff reduction was high for Subarnrekha basin (54.1 %). Rainfall to runoff conversion was high for Brahmaputra-Barak basin (72 %), while coefficient of variation for runoff was more for Mahanadi basin (1.88). Study indicates that eastern India agriculture will be affected due to shortage of surface water availability.