Estimation of curve numbers for different soil conservation measures in lateritic soil of south Konkan region

Seven years (1992–1998) rainfall data of Agricultural Research Station, Mulde, District Sindhudurge in South Konkan of Maharashtra State was analyzed for every storm to determine storm wise AMC condition. The entire events, fall in each AMC I, II, III were grouped in small, medium and large class. The potential retention (S), value for different storm group with different AMC was then computed by using lognormal distribution for runoff and rainfall pair data. This potential retention value was used for the computation of CN for given condition of the watershed. The estimated average CNs for different conservation measures for AMC I, II, III are 77.93, 81.31 and 84.57, respectively. The VGB produces more runoff followed by NCM, ST and RT. The standard error was also higher in case of NCM (36.28%), which was then followed by VGB (30.64%), PT (20.65%) and other micro watershed (1.68 to 19%). The mean percent runoff factors observed were 45.70, 23.99, 24.45, 23.55, 26.32 and 50.27 for NCM, IBT, ST, PT, RT and VGB, respectively. The intermittent bench terracing (IBT) and platform terraces (PT) were found more effective in controlling the runoff to other conservation measures. The observed and computed runoff from study area was found non significant at 5% level of confidence. Hence, Computed CNs can be used for estimation of runoff from an ungauged watershed.