ISC-2012.C1.09 ESTIMATION OF PRECIPITATION VARIABILITY FROM SATELLITE DATA OVER GANGA BASIN, INDIA Sudhakar Sharma Department of Civil Engineering, Nirma University, Ahmedabad, India sudhakar.sharma@nirmauni.ac.in Santosh S Kolte Department of Civil Engineering, Nirma University, Ahmedabad, India santoshkolte@nirmauni.ac.in Anupam K Singh Department of Civil Engineering, Pandit Deendayal Petroleum University, Ahmedabad, India anupam.singh@gmx.ne t R M Gairola GRD/EOSG/EPSA, Space Applications Centre, Ahmedabad, India rmgairola@sac.isro.gov.in Abstract In this research paper, Tropical Rainfall Measuring Mission (TRMM) satellite data has been used to derive rain - fall amount and compare with ground-measured values over Ganga basin of India. The 3B43 version of the al - gorithm is used to provide the best precipitation estimate on every 0.25°x 0.25° grid (approx. 27.8 × 27.8 km) within the TRMM region, from all global data sources from January 1998 to December 2011. It is the merged product of TRMM and other microwave satellite sensors, geosynchronous IR, and rain gauges. TRMM data has been downloaded in “Netcdf*” file format from NASA’s website for 14 years from 1998 to 2011 at the monthly scale in the form of rain-rate. The Ganga basin of North-East India has been selected for calculating rainfall amount variations. The Ganga basin of North-East India has been selected for calculating rainfall amount variations. The geographical area of Ganga basin is 906,876 km 2 and the river length is 2525 km. The spatial distribution of monthly average rainfall and isohyets are geneated for every month using Geo-statistic- al method in GIS environments. Rainfall data is also plotted and correlated with ground observation data. The overall catchments rainfall was well represented by TRMM data in GIS environments However, the annual station rainfalls are found to either underestimate or overestimate at some locations. Overestimation between 10% to 20% were found at high elevation locations at Haridwar and Etah, and the underestimation between 5% to 10% were found at low elevated areas of Raebreli, Varanasi and Howara. Although, the TRMM rainfall data did not perfectly match with the ground measurements but it provides a useful tool for supple - mentary ground measurements data for un-gauged basins. Keywords: Ganga Basin, TRMM, Rainfall, GIS etc.