ABSTRACT
The Langtang catchment is a high mountain, third order catchment in the Gandaki basin in the Central Himalaya (28.2°N, 85.5°E), that eventually drains into the Ganges. The catchment spans an elevation range from 1400 to 7234 m a.s.l. and approximately one quarter of the area is glacierized. Numerous research projects have been conducted in the valley during the last four decades, with a strong focus on the cryospheric components of the catchment water balance. Since 2012 multiple weather stations and discharge stations provide measurements of atmospheric and hydrologic variables. Full weather stations are used to monitor at an hourly resolution all four radiation components (incoming and outgoing shortwave and longwave radiation; SWin/out and LWin/out), air temperature, humidity, wind speed and direction, and precipitation, and cover an elevational range of 3862-5330 m a.s.l. Air temperature and precipitation are monitored along elevation gradients for investigations of the spatial variability of the high mountain meteorology. Dedicated point-scale observations of snow cover, depth and water equivalent as well as ice loss have been carried out over multiple years and complement the observations of the water cycle. All data presented is openly available in a database and will be updated annually.
ABSTRACT
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.
ABSTRACT
Future hydrological extremes, such as floods and droughts, may pose serious threats for the livelihoods in the upstream domains of the Indus, Ganges, Brahmaputra. For this reason, the impacts of climate change on future hydrological extremes is investigated in these river basins. We use a fully-distributed cryospheric-hydrological model to simulate current and future hydrological fluxes and force the model with an ensemble of 8 downscaled General Circulation Models (GCMs) that are selected from the RCP4.5 and RCP8.5 scenarios. The model is calibrated on observed daily discharge and geodetic mass balances. The climate forcing and the outputs of the hydrological model are used to evaluate future changes in climatic extremes, and hydrological extremes by focusing on high and low flows. The outcomes show an increase in the magnitude of climatic means and extremes towards the end of the 21st century where climatic extremes tend to increase stronger than climatic means. Future mean discharge and high flow conditions will very likely increase. These increases might mainly be the result of increasing precipitation extremes. To some extent temperature extremes might also contribute to increasing discharge extremes, although this is highly dependent on magnitude of change in temperature extremes. Low flow conditions may occur less frequently, although the uncertainties in low flow projections can be high. The results of this study may contribute to improved understanding on the implications of climate change for the occurrence of future hydrological extremes in the Hindu Kush-Himalayan region.
