Modeling Freshwater Supply from its Origin: at High-Altitude Glaciers

Abstract

Meltwater from glaciers in high-altitude mountains feed the populations that live in their basins and catchment areas. Their freshwater supply, hydroelectric power and irrigation is extremely sensitive to the changing climate conditions. This study investigates the impact on freshwater supply under these conditions by modeling the mass balance of high-altitude glaciers. The two areas whose mass balances have been investigated are the Himalayas and the Andes. There are 1.3 billion people who depend on Himalayan glaciers as their source of water. The Andean region has 3.5 million residents all of whom depend almost entirely on the meltwater from the mountain's glaciers. This study examines the Himalayas and the Andes, and also analyses freshwater supply from 1950 to the present day and projects the impact on freshwater supply to 2100, providing suggestions for freshwater resource management. The results show that the Himalayan glaciers have increasingly negative mass balance, implying the glaciers are shrinking. Projections computed in this study indicate that important glaciers, such as the Dokirani glacier that is a source of water for the River Ganga, will disappear by the 2060s. The most notable exception is the Karakoram region of the Himalayas whose anomalously high precipitation leads to increasing mass balances and glaciers that grow over time. One of the biggest geostrategic implications is that the highest active warzone in the world, Siachen glacier, will continue to grow. Furthermore it will be a source of freshwater for regions that lack it, increasing the need for a water agreement and a peaceful settlement. The results of this study show that Andes have mass balances that are not only lower but also decreasing at a quicker rate. The principal areas of interest are the central Andes and the Northern and Southern Patagonian ice fields. Glaciers in the central Andes are projected to disappear by 2100. The glaciers in the Central Andes are seen to shrink at an alarming rate from the 2030s onwards, and several of these glaciers' masses approach zero. In the Patagonia icefield, particularly in the southern icefield which contains the most (and largest) glaciers, the shrinking glaciers and their falling mass balances severely restrict the freshwater supply available to the region. For instance Parinacota 01 glacier is projected to disappear in the 2020s and Solimana glacier is projected to disappear between 2060 and 2100. The projections of freshwater supply and recommendations for resource management that this study makes point to a future with water shortages, bilateral water agreements and an increasing need for vulnerability analyses and proactive freshwater distribution today.