Abstract

We examined the effect of land cover on stream discharge in hilly catchment streams during extreme rain events. Three years of rainfall-runoff observations, between January 2014 and December 2016, were collected in eleven neighbouring catchments. Each catchment was dominated by a different land cover, namely natural shola forests, natural grasslands and wattle (Acacia mearnsii). Rain intensities between percentiles 25-90, 90-95 and over 95 were categorised as light, heavy and extreme and were used to study stream discharge responses. Land cover significantly influenced the hydrologic response to extreme rain events. During light rains (< 38 mm/day), grassland dominated catchments showed higher discharge than shola (0.01 mm/s) and wattle (0.004 mm/s). However, during extreme rain events (> 71 mm/day) discharge was significantly higher in wattle dominated catchments when compared to the natural shola (0.033 mm/s) and grasslands (0.023 mm/s). Antecedent moisture conditions played a major role in determining peak flows along with rainfall, catchment shape and drainage density.