Hydro-climatic extremes in the Himalayan watersheds: a case of the Marshyangdi Watershed, Nepal
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ORIGINAL PAPER
Hydro-climatic extremes in the Himalayan watersheds: a case of the Marshyangdi Watershed, Nepal Reeta Singh 1 & Vishnu Prasad Pandey 2
&
Sadhana Pradhanang Kayastha 1
Received: 12 June 2020 / Accepted: 17 September 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Climate change/variability and subsequent exacerbation of extremes are affecting human and ecological health across the globe. This study aims at unpacking hydro-climatic extremes in a snow-fed Marshyangdi watershed, which has a potential for water infrastructure development, located in Central Nepal. Bias-corrected projected future climate for near (2014–2033) and midfuture (2034–2053) under moderate and pessimistic scenarios were developed based on multiple regional climate models. Historical (1983–2013) and future trends of selected climatic extreme indices were calculated using RClimDex and hydrological extremes using Indicators of Hydrologic Alteration tool. Results show that historical trends in precipitation extremes such as number of heavy and very heavy precipitation days and maximum 1-day precipitation are decreasing while the temperaturerelated extremes have both increasing and decreasing trends (e.g., warm spell duration index, warm days and summer days are increasing whereas cold spell duration index, cool days and warm nights are decreasing). These results indicate drier and hotter conditions over the historical period. The projected future temperature indices (hot nights, warm days) reveal increasing trend for both the scenarios in contrast with decreasing trends in some of the extreme precipitation indices such as consecutive dry and wet days and maximum 5-day precipitation. Furthermore, the watershed has low mean hydrological alterations (27.9%) in the natural flow regime. These results indicate continuation of wetter and hotter future in the Marshyangdi watershed with likely impacts on future water availability and associated conflicts for water allocation, and therefore affect the river health conditions. Abbreviations CD Coefficient of dispersion CPA Change-point analysis DHM Department of Hydrology and Meteorology H High HA Hydrologic alteration IHA Indicators of Hydrologic Alteration IPCC International Panel for Climate Change L Low M Moderate masl mean above sea level MF Mid-future NF Near future OD Overall degree P Percentage of deviation * Vishnu Prasad Pandey [email protected] 1
Central Department of Environmental Sciences (CDES), Tribhuvan University, Kirtipur, Nepal
2
International Water Management Institute (IWMI), Nepal Office, Lalitpur, Nepal
PPT Q RCM RCP RVA Tmax Tmin
Precipitation Discharge Regional climate model Representative concentration pathway Range of variability approach Maximum temperature Minimum temperature
1 Introduction Climate change and variability is recognized as a major threat for the environment and sustainable development (Lal et al. 2012). It is evident that a change in the climate, depending upon location, may cause disastrous consequences on the so
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