Increasing water stress in developing countries

Global water scarcity is an escalating issue, with billions of people facing severe water stress and limited access to water for extended periods each year. Climate change and increasing human demand are expected to exacerbate this problem in the coming decades. Reservoirs are critical for managing water resources, yet significant disparities exist between developed and developing countries. In developing regions, although total reservoir storage is increasing, the effectiveness of this storage is diminishing, as reflected in declining normalized storage levels. This indicates that these countries are becoming more vulnerable to water scarcity. In contrast, developed countries show more stable and efficient use of their water storage. The declining per-capita water storage across both developed and developing nations underscores the urgency of addressing water scarcity through improved reservoir management, enhanced conservation efforts, and alternative water sources, especially in regions with rapid population growth and limited resources.

Over 2 billion people are experiencing high water stress, and around 4 billion are suffering from severe water scarcity for at least one month each year. Meanwhile, increasing water demand for industrial and domestic purposes is projected to boost global water use by 20%–33% by 2050 compared to 2010 levels. Climate change, exacerbated by human activities, is expected to intensify water scarcity both regionally and globally. Over the past two decades, floods and droughts have caused over 166,000 deaths, affected more than 3 billion people, and incurred nearly $700 billion in economic losses. In response, reservoirs—designed for functions such as water supply, hydropower, irrigation, and flood control—are becoming increasingly vital in the context of a changing climate, especially in developing countries. Although reservoirs represent only about 4% of the total storage capacity of lakes and reservoirs, they account for 61% of the variability in surface water storage.