Modelling the Future of Indus Glacier Water Resources: Interactions between Glacier Retreat and Water Demand

Glaciers in the Indus are critical water resources, supporting agriculture, hydropower, and livelihoods for hundreds of millions of people downstream, especially during the dry season. Here, we assess changes in the future water availability from melting glaciers in the Indus basin and how this will impact future water scarcity risks. We model the evolution of all glaciers, in the Indus, larger than 0.5km² using the Global Glacier Evolution Model (GloGEM), calibrated with transient snowline altitudes and geodetic mass balance observations. Glacier runoff projections are combined with water demand simulations from the ISIMIP3b dataset on total potential water withdrawal allowing us to explore potential future risks of water scarcity under SSP1-2.6 and SSP5-8.5 scenarios.

We analyse two different scenarios: (i) future changes in glacier runoff with present-day (2001-2020) water demand held constant, (ii) concurrent changes in both future glacier runoff and water demand. Preliminary results show that ongoing glacier mass loss in the Indus basin substantially changes the magnitude and seasonal distribution of glacier runoff. Timing of  peak seasonal ablation is shifted by up to several weeks, and the overall amount of glacier runoff is reduced, which has implications for downstream water availability, particularly during the early and late summer months, when demand is highest. By disentangling the contribution of glacier runoff to water demand, this study aims to quantify the vulnerability of the Indus to future water stress and to identify conditions under which glacier retreat may exacerbate or temporarily mitigate water scarcity.