Hydrological data analysis for small black soil agricultural catchments in dryland zone of Karnataka

The data collected from small farm catchments ranging between 1 to 3 ha under semi arid black soil region was subjected to hydrological and soil erosion analysis. It was observed that maximum rainfall, runoff and soil loss occurred during the month of September followed by October and June. Annual runoff and soil loss was observed to be as high as 119 mm and 11 t/ha/year in 25 year return period suggesting that the area is prone to severe soil erosion. Climatic water balance analysis showed that in each month potential evapotranspiration was more than that of rainfall and hence water deficit exists throughout the year. There was minimum water deficit and maximum soil water availability in the month of September, foIlowed by October and November, whereas, maximum water deficit was observed to be in March and April. Attempt was also made to develop linear and multiple linear regression equations to predict runoff from rainfall, intensity and antecedent rainfall conditions. Return period analysis of rainfall, runoff and soil loss data is also presented in this paper.