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      https://www.ias.ac.in/article/fulltext/jess/126/02/0022

    • Keywords

       

      Tons river basin; sediment flux; denudation rate; small hydropower plants; extreme precipitation; Lesser Himalaya.

    • Abstract

       

      Climatic extremes including precipitation are bound to intensify in the global warming environment. The present study intends to understand the response of the Tons sub-watershed in Lesser Himalaya, in 3 years with entirely different hydrological conditions (July 2008–June 2011) in terms of discharge, sedimentflux and denudation rates. Within an uncertainty limit of ±20%, the mean interannual discharge (5.74 ± 1.44 m ³s ⁻¹) (±SE), was found highly variable (CV: 151%; 0.8–38 m ³s ⁻¹). In a normal rainfall year (2008–2009; ~1550 mm), the discharge was 5.12 ± 1.75 m ³s ⁻¹, whereas in a drought year (2009–2010), it reduced by 30% with the reduction in ~23% rainfall (CV: 85%). In an excessive rainfall year (once-in-a-century event) (2010–2011; ~3050 mm), discharge as well as total solid load was ~200% higher. Monsoon months (July–September) accounted for more than 90% of the annual solid load transport. The ratio of dissolved to suspended solid (C/P ratio) was consistently low (<1) during monsoon months and higher (1–7) during the rest of the dry period. C/P ratio was inversely (R ² = 0.49), but significantly (P<0.001) related to the rainfall. The average mechanical erosion rate in the three different rainfall years was 0.24, 0.19 and 1.03 mmyr ⁻¹, whereas the chemical erosion was estimated at 0.12, 0.11 and 0.46 mmyr ⁻¹, respectively. Thus, the average denudation rate of the Tons sub-watershed has been estimated at 0.33 mmyr ⁻¹ (excluding extreme rainfall year: 1.5 mmyr ⁻¹). Our results have implications to understand the hydrological behaviour of the Lesser Himalayan watersheds and will be valuable for the proposed and several upcoming small hydropower plants in the region in the context of regional ecology and naturalresource management.

    • Author Affiliations

       

      Pankaj Chauhan1 Nilendu Singh1 Devi Datt Chauniyal2 Rajeev S Ahluwalia1 Mohit Singhal1

      1. Wadia Institute of Himalayan Geology, Dehradun 248 001, India.
      2. School of Earth Science, HNB Garhwal University, Srinagar 246 174, India.
    • Dates

       
  • Journal of Earth System Science | News

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