A systematic framework for the assessment of sustainable hydropower potential in a river basin - The case of the upper Indus.

Siloed-approaches may fuel the misguided development of hydropower and subsequent target-setting under the sustainable development goals (SDGs). While hydropower development in the Indus basin is vital to ensure energy security (SDG7), it needs to be balanced with water use for fulfilling food (SDG2) and water (SDG6) security. Existing methods to estimate hydropower potential generally focus on: only one class of potential, a methodological advance for either of hydropower siting, sizing, or costing of one site, or the ranking of a portfolio of projects. A majority of them fall short in addressing sustainability. Hence, we develop a systematic framework for the basin-scale assessment of the sustainable hydropower potential by integrating considerations of the water-energy-food nexus, disaster risk, climate change, environmental protection, and socio-economic preferences. Considering the case of the upper Indus, the framework is developed by combining advances in literature, insights from local hydropower practitioners and over 30 datasets to represent real-life challenges to sustainable hydropower development, while distinguishing between small and large plants for two run-of-river plant configurations. The framework first addresses theoretical potential and successively constrains this further by stepwise inclusion of technical, economical, and sustainability criteria to obtain the sustainable exploitable hydropower potential. We conclude that sustainable hydropower potential in complex basins such as the Indus goes far beyond the hydrological boundary conditions. Our framework enables the careful inclusion of factors beyond the status-quo technological and economic criterions to guide policymakers in hydropower development decisions in the Indus and beyond. Future work will implement the framework to quantify the different hydropower potential classes and explore adaptation pathways to balance SDG7 with the other interlinked SDGs in the Indus.

Hydrological response of Chamelia watershed in Mahakali Basin to climate change.

Chamelia (catchment area = 1603 km2), a tributary of Mahakali, is a snow-fed watershed in Western Nepal. The watershed has 14 hydropower projects at various stages of development. This study simulated the current and future hydrological system of Chamelia using the Soil and Water Assessment Tool (SWAT). The model was calibrated for 2001-2007; validated for 2008-2013; and then applied to assess streamflow response to projected future climate scenarios. Multi-site calibration ensures that the model is capable of reproducing hydrological heterogeneity within the watershed. Current water balance above the Q120 hydrological station in the forms of precipitation, actual evapotranspiration (AET), and net water yield are 2469 mm, 381 mm and 1946 mm, respectively. Outputs of five Regional Climate Models (RCMs) under two representative concentration pathways (RCPs) for three future periods were considered for assessing climate change impacts. An ensemble of bias-corrected RCM projections showed that maximum temperature under RCP4.5 (RCP8.5) scenario for near-, mid-, and far-futures is projected to increase from the baseline by 0.9 °C (1.1 °C), 1.4 °C (2.1 °C), and 1.6 °C (3.4 °C), respectively. Minimum temperature for the same scenarios and future periods are projected to increase by 0.9 °C (1.2 °C), 1.6 °C (2.5 °C), and 2.0 °C (3.9 °C), respectively. Average annual precipitation under RCP4.5 (RCP8.5) scenario for near-, mid-, and far-futures are projected to increase by 10% (11%), 10% (15%), and 13% (15%), respectively. Based on the five RCMs considered, there is a high consensus for increase in temperature but higher uncertainty with respect to precipitations. Under these projected changes, average annual streamflow was simulated to increase gradually from the near to far future under both RCPs; for instance, by 8.2% in near-, 12.2% in mid-, and 15.0% in far-future under RCP4.5 scenarios. The results are useful for planning water infrastructure projects, in Chamelia and throughout the Mahakali basin, to ensure long-term sustainability under climate change.