Runoff estimation by composite and distributed curve number methods using remote sensing data

Abstract

The comparison between composite and distributed curve number methods for runoff estimation was carried out in a study undertaken in the Kathajodi-Surua Inter-basin in the Odisha state of Eastern India. Indian Remote Sensing IRS P6 MX images were analyzed for classifying the land use/land cover of the study basin. The land use/land cover map of the basin were superimposed with the corresponding soil map to come out with the hydrologic soil cover complex or curve number distribution in the basin. The composite curve number of the entire area was computed by weighted average of the curve number of each polygon in the hydrologic soil cover complex map with respect to their area. Using distributed curve number technique, runoff was simulated at each grid and averaged at the outlet of the basin and finally compared with the values obtained from compositing technique. The study revealed that there is definite increase in runoff value estimated by distributed curve number method over the traditional composite curve number method. The higher estimated runoff in distributed curve number method has been explained by a hypothetical example