Abstract
Water stored in the form of snow and glaciers in the High Mountain Asia (HMA) region regulates the water supply, and resultant water-based economies, that support the livelihoods of about 1.4 billion people. Trends in the seasonal and long-term melting of snow and glaciers, governed by initial ice reserves, meteorological factors and geographic features, vary across sub-basins in the HKH region. We examined the economic impacts of climate-led changes in river flow in two drainage basins, one each from the Karakoram and Central Himalaya region. We used an integrated assessment framework to estimate the changes in economic value of the hydropower generation from hydropower plants on rivers fed by snow and glacier melt in the two sub-basins. The framework, developed under a NASA High Mountain Asia project, coupled biophysical models (a suite of climate models, snow/glacier-hydrology, and hydropower models) with economic analysis. We compared the differences in estimated river flow over historic and future time using the water balance model in sixteen scenarios (eight climate models and two emissions scenarios) for rivers upstream of hydropower plants in each sub-basin. Using the hydropower model, we estimated the changes in hydropower generation at the Naltar IV hydropower plant, with an 18 MW capacity, located in Hunza, Karakoram, and the Trishuli hydropower plant, with a 19.6 MW capacity, in Trishuli, Central Himalaya. When compared to their baselines, the estimated impact of climate change and temporal variability were higher for the Naltar plant than for the Trishuli plant. Our sensitivity analysis shows that hydropower plants with water storage facilities help reduce the impact of changes, but the estimated impacts are higher for the higher capacity plants. This study provides an example of the differential impacts of climate change on hydropower plants located in rivers fed by varying amounts of snow and glacier melt at different decades in this century. This type of integrated assessment of climate change impact will support the scientific understanding of hydrologic flow and its impacts on a hydropower economy under various climate scenarios, as well as generate information about water resource management in a changing climate.
Highlights
Water stored in the form of snow and glaciers in the High Mountain Asia (HMA) region regulates the water supply, and resultant water-based economies, that support the livelihoods of millions of people (Viviroli et al, 2011; Lutz et al, 2014; Biemans et al, 2019; Immerzeel et al, 2019; Pritchard, 2019)
Interactions within and among physical processes and economic activities, such as those that occur during global climate change, are both complex and uncertain (Abbasi et al, 2017)
Our study customized an integrated assessment-modeling framework to explore and learn about the relative impacts of projected changes in river flow and its constituents — snow and glacier melt and rainfall — in two basins located in different sub-regions of HMA
Summary
Water stored in the form of snow and glaciers in the High Mountain Asia (HMA) region regulates the water supply, and resultant water-based economies, that support the livelihoods of millions of people (Viviroli et al, 2011; Lutz et al, 2014; Biemans et al, 2019; Immerzeel et al, 2019; Pritchard, 2019). The extent of westerly and monsoon influence varies with the location of a given sub-basin in the region, but the melting of snow and glaciers differ from sub-basin to sub-basin depending upon such factors as the quantity, location and orientation of snowpack, solar radiation, rainfall, etc. Governments in this region have been encouraging the development of relatively low-cost electricity production from hydropower plants to meet the increasing demand for electricity in the region. Information about projected changes in river flow, seasonally and over the century, is important for infrastructure development and planning downstream, including critical hydropower and irrigation infrastructure
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