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Exotic Plantations Increase Risks of Flooding in Mountainous Landscapes
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  • Rajat Nayak,
  • Jagdish Krishnaswamy,
  • Srinivas Vaidyanathan,
  • Nick Chappell,
  • Kumaran Kesavan,
  • Prachi Ghatwai,
  • Ravinder Singh Bhalla
Rajat Nayak
Foundation for Ecological Research, Advocacy and Learning, Foundation for Ecological Research, Advocacy and Learning
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Jagdish Krishnaswamy
Ashoka Trust for Research in Ecology and the Environment, Ashoka Trust for Research in Ecology and the Environment
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Srinivas Vaidyanathan
Foundation for Ecological Research, Advocacy and Learning, Foundation for Ecological Research, Advocacy and Learning
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Nick Chappell
Lancaster University, Lancaster University
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Kumaran Kesavan
Foundation for Ecological Research, Advocacy and Learning, Foundation for Ecological Research, Advocacy and Learning
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Prachi Ghatwai
Ashoka Trust for Research in Ecology and the Environment, Ashoka Trust for Research in Ecology and the Environment
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Ravinder Singh Bhalla
Foundation for Ecological Research, Advocacy and Learning, Foundation for Ecological Research, Advocacy and Learning

Corresponding Author:[email protected]

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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.