Plot scale assessment of effect of watershed features on runoff and sediment generation in Uttarakhand, India

Daily runoff and sediment from twelve plots (22 m × 5 m) having various land uses (Sugracane, Blackgram, Maize and Fallow land) and slopes (5, 3 and 1%) recorded during the period of June 2014 to April 2015 in the Roorkee, Uttarakhand (India) were analysed together with daily rainfall to assess the effects of land use, soil type and antecedent soil moisture on runoff and sediment yield. The total annual surface runoff generated at 12 study plots was varied from 559.5 m³/ha to 1491.2 m³/ha with an average of 991.1 m³/ha. The total annual sediment yield varied between 0.673 t/ha to 2.63 t/ha. The higher value (= 2.63 t/ha) of sediment yield observed from the present study is lower than the soil erosion tolerance limit (2.5 to 12.5 t/ha/yr) for Indian subcontinent. The trend variability of runoff was higher than rainfall, indicating nonlinear relationship between both variables. Rainfall amount is significantly correlated to runoff amount and coefficient of determination (R²) ranged between values 0.435 to 0.82. Regression analyses revealed that sediment yield was more closely correlated to runoff than rainfall. The determination coefficient (R²) of the relationship between runoff and sediment yield for different land use was ranged 0.17 to 0.823. Land use type was an important explanatory factor for the variation in runoff and sediment, whereas slope was not. On average, the plots with sugarcane land use were found to produce higher amount of runoff as well as sediment followed by Maize, Blackgram and fallow land. In addition, both runoff coefficient and sediment yield were found to decreased with final infiltration rate of plots. The previous day soil moisture does not seem to play important role on hydrological response as event runoff coefficient (C) was found to correlate insignificantly with previous day soil moisture (θ).