This study found that the existing strategies are insufficient to provide safe and adequate water in Kathmandu Valley. This is proved by the fact that more than five million people would be deprived of the minimum needed water by 2050 even under the current climate which would become worse under the driest scenario of climate change. Similarly, the reduction in the dry season river flow under the driest scenario or frequent extreme rainfall events under the wettest scenario could further degrade the water quality and increase the vulnerability of water supply infrastructures. However, it is possible to manage the situation by adopting a combination of strategies including: rooftop rainwater harvesting, artificial groundwater recharge, grey water recycling and reducing overall water demand. The situation would become worse after 2050 due to the projected sharp reduction (up to 95%) in precipitation, which, in turn, would make all precipitation-dependent water supply strategies ineffective. In such a situation only limited options such as the population control and full recycling would be available. The result of the study should be taken as an indication only, as there is no agreement among General Circulation Models (GCMs) on the expected scenario of climate change.
