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<p>This study addresses critical knowledge gaps about climate change impacts on hydrology and water resources in a highly vulnerable and important region for water resources and electricity production. A sub-catchment, Balganga River upstream Sarasgaon gauge as part of the Bhilangana River basin in the Indian Central Himalayas, was analysed using observed and projected future climate data for precipitation and temperature. Examining the maximum monthly rainfall data provided by the India Meteorological Department (IMD) spanning from 1901 to 2020 reveals a noteworthy shift in the peak towards earlier months, particularly up to June. This observation suggests compelling evidence of seasonal changes in flood peaks potentially associated with a warming climate scenario. Upon comparing different data sets with observed data sets, it was found that the Indian Meteorological Department (IMD) precipitation dataset best matche<b>s</b> the observations. The projected climate ensemble of the chosen dataset (NEX-GDDP) required significant bias correction before it could be used for any purpose. Hydrological modelling was done using the combined CemaNeige_GR4J model system to project changes in floods for historical and future scenarios. The model was calibrated with observed discharge data for the Sarasgaon gauge and showed good agreement with discharge observation data. Scenario simulation was done for historical (1971–1999), RCP 4.5 (2071–2099), and RCP 8.5 (2071–2099) scenarios based on calibrated parameters. The results indicated the possibility of vanishing snowpacks in the study area in the future. Due to higher temperatures and precipitation in the future, the simulated future discharge series of RCP 8.5 is magnitude-wise higher than that of future conditions under RCP 4.5, which in turn is higher than that of the historical conditions during the monsoon season. Regarding the timing of annual maximum flood peaks, a possible early shift is indicated for future conditions if a combination of snowmelt and rainfall-induced floods occurs in the study region. This shows the possible occurrences of changing flood composition, though one must be aware of the high uncertainties of projected future precipitation, temperature conditions, and the resulting streamflow. Overall, the study highlights the potential impact of climate change on floods in the Garhwal Himalayas region, emphasising the relevance of different flood-generating processes. The findings underscore the need for future measuring programs, modelling and data analysis research. This may further form the basis for flood risk adaptation strategies in the Himalayan region and reduce the associated uncertainties.</p>

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Understanding the flood seasonality in a Himalayan River Basin under changing climate

  • 期刊论文

  • 发表日期：

    2025年6月12日

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  • Prachi Singhal,
  • Narendra K. Goel,
  • Axel Bronstert,
  • Klaus Vormoor,
  • Ankit Agarwal,
  • Manohar Arora

摘要

This study addresses critical knowledge gaps about climate change impacts on hydrology and water resources in a highly vulnerable and important region for water resources and electricity production. A sub-catchment, Balganga River upstream Sarasgaon gauge as part of the Bhilangana River basin in the Indian Central Himalayas, was analysed using observed and projected future climate data for precipitation and temperature. Examining the maximum monthly rainfall data provided by the India Meteorological Department (IMD) spanning from 1901 to 2020 reveals a noteworthy shift in the peak towards earlier months, particularly up to June. This observation suggests compelling evidence of seasonal changes in flood peaks potentially associated with a warming climate scenario. Upon comparing different data sets with observed data sets, it was found that the Indian Meteorological Department (IMD) precipitation dataset best matches the observations. The projected climate ensemble of the chosen dataset (NEX-GDDP) required significant bias correction before it could be used for any purpose. Hydrological modelling was done using the combined CemaNeige_GR4J model system to project changes in floods for historical and future scenarios. The model was calibrated with observed discharge data for the Sarasgaon gauge and showed good agreement with discharge observation data. Scenario simulation was done for historical (1971–1999), RCP 4.5 (2071–2099), and RCP 8.5 (2071–2099) scenarios based on calibrated parameters. The results indicated the possibility of vanishing snowpacks in the study area in the future. Due to higher temperatures and precipitation in the future, the simulated future discharge series of RCP 8.5 is magnitude-wise higher than that of future conditions under RCP 4.5, which in turn is higher than that of the historical conditions during the monsoon season. Regarding the timing of annual maximum flood peaks, a possible early shift is indicated for future conditions if a combination of snowmelt and rainfall-induced floods occurs in the study region. This shows the possible occurrences of changing flood composition, though one must be aware of the high uncertainties of projected future precipitation, temperature conditions, and the resulting streamflow. Overall, the study highlights the potential impact of climate change on floods in the Garhwal Himalayas region, emphasising the relevance of different flood-generating processes. The findings underscore the need for future measuring programs, modelling and data analysis research. This may further form the basis for flood risk adaptation strategies in the Himalayan region and reduce the associated uncertainties.