Estimation of curve number for major basins of India using remote sensing

The Soil Conservation Service Curve Number (SCS-CN) method is commonly used to estimate direct surface runoff. Very little work has been done to estimate curve numbers of major basins of India. This study is an attempt to estimate the curve number (CN) at everyone sq km area for major basins in India using satellite remote sensing data and ancillary data. Thirty nine dates of SPOT VEGETATION 10-day composite data of India for the year 2001–02 was used to derive hydrological land cover classes. These were integrated with hydrological soil groups to derive hydrological soil cover complex (HSCC), which is used to derive curve number. It was found that average Curve Number ranges from 68 to 82. The average curve number of mainland of India was estimated to be 76. This means that considerable high amount of direct runoff is expected in India. The spatial pattern of curve number indicated the presence of variability in curve number due to variety of land cover and hydrological soil groups. The curve number is more dominated by hydrological soil group thall land cover except in case of the Brahmputra basin.