No abstract

in the past, to derive the unit hydrograph (UH) various distribution functions have been utilized so far, though they had their own limitations. In this study, the applicability of two-parameter beta distribution has been explored for the derivation of UH. The parameters of the distribution function were estimated using the Genetic Algorithm which facilitates the minimization of global error.The suitability of the derived UH resulting from the two-parameter beta distribution was verified by comparing the UH derived by the two-parameter gamma distribution. The results obtained from both the distributions were almost similar and close to the observed UHs, which confirmed the applicability of the two-parameter beta distribution as an alternate approach for the derivation of the UH.

Planning and strategic management of irrigation water are the key elements for successful crop production. In this study, evaluation of crop coefficients (K C ) on daily and seasonal basis was accomplished for rabi (winter or post rainy) sorghum in semi-arid climatic conditions of India. The crop coefficients for sorghum were developed using lysimetric measured actual crop evapotranspiration (ET C ) and reference evapotranspiration (ET O ) based on the FAO 56 Penman Monteith Method (FP-M). The developed K C values for sorghum during initial, crop development, mid-season, late season stages and at harvest were 0.65, 0.60, 0.50, 0.24, and 0.14, respectively. The results indicated that the actual K C values were considerably different and lower than those suggested by FAO indicating the need for developing these values at the local scale. The measured K C in initial stage was higher than that of empirical K C suggested in FAO 56 whereas K C at development (pre-flowering) stage is in close conformity with that of FAO empirical K C when sufficient moisture was present in the soil. However, the unusual decreasing trend of measured K C from 55 days after sowing of crop at flowering and grain formation stage strongly pointed towards the need of at least two protective irrigations for successful sorghum crop production if grown under rainfed situations.