CONTENTS
HIGHLIGHTS
Population Reports is published by the Population Information Program, Center for Communication Programs, The Johns Hopkins School of Public Health, 111 Market Place, Suite 310, Baltimore, Maryland 21202-4012, USA
Fall 2000
Series M, Number 15 |
Water ShortagesAlready, population growth and rising use per capita are creating water shortages in many countries. A country is said to experience water stress when annual water supplies drop below 1,700 cubic meters per person. When supplies drop below 1,000 cubic meters per person per year, the country faces water scarcity for all or part of the year. Swedish hydrologist Malin Falkenmark developed these concepts of stress and scarcity to gauge current and future water needs against available supplies (64, 66, 82). In 1995 Population Action International (PAI) adapted Falkenmark's concepts to calculate water stress and scarcity in countries around the world. PAI updated this estimate in 1997, based on population projections for 2025 and 2050. The results are startling: In 1995, 31 countries—home to nearly half a billion people—regularly faced either water stress or water scarcity. In 2025, 48 countries, with about 3 billion people, are projected to face water shortages (60, 82). The 20 countries of the Near East and North Africa face the worst prospects. In fact, the Near East "ran out of water" as long ago as 1972—in the sense that since then the region has withdrawn more water from its rivers and aquifers than is being replenished by nature (154). Currently, for example, Jordan and Yemen withdraw 30% more water from groundwater supplies every year than is replenished; Israel's annual water use exceeds the renewable supply by 15% (183, 185). Africa also faces serious water problems. Already, over 200 million Africans live in water-stressed or water-scarce countries. By 2025 the number will rise to about 700 million, of whom over half will live in countries that face severe shortages for most of the year (65, 67, 182). If water stress and water scarcity were calculated for regions instead of countries, parts of many other countries would be considered at risk. For example, while periodic flooding afflicts the southern part of China, the northern part faces chronic water shortages (22, 82). China's freshwater supplies have been estimated to be capable of supporting 650 million people on a sustainable basis—only about half the country's current population (190). Competing for water supplies. When water supplies become scarce, competition can become intense. In recent years withdrawals of freshwater have grown in all categories of demand—for irrigated agriculture, industrial use, and municipal (household) purposes (139, 222, 244). Freshwater demand for municipal use is expected to outpace the capacity of many cities to provide it (237). In Bangkok, Dhaka, Lagos, and other rapidly growing cities, water theft has become widespread (137, 173, 220). Because more than 200 major river systems cross national borders, cooperation can help avoid international conflict. For example, in November 1999 Egypt, Ethiopia, and Sudan agreed in principle on a strategy for using the Nile River "for the common benefit of all the river basin states" (172). If implemented, the agreement—which covers all uses of the river, for irrigation, hydropower, drainage, drought and flood control, and pollution prevention—would be a breakthrough in cooperative use of a vital natural resource. Competing with nature. A substantial portion of the total freshwater supply is needed to sustain marshes, rivers, coastal wetlands, and the millions of species they shelter (68). As humanity withdraws more freshwater for direct use, less is available to maintain wetland ecosystems (12, 184, 187). Over 20% of the approximately 10,000 freshwater fish species in the world are either endangered or are already going extinct because their habitats are being threatened (18, 120) (see Chapter 7.1). Wetland ecosystems are economically valuable. Robert Costanza of the University of Maryland estimates the global value of wetlands at close to US$5 trillion a year. This amount reflects the value of wetlands as flood regulators, waste treatment plants, wildlife habitats, fisheries production, and recreation (107). The world's 6 billion people are already appropriating just over half of all the accessible freshwater contained in rivers, lakes, and underground aquifers. By 2025 humankind's share will be at least 70%. This conservative estimate reflects the impact of population growth alone. If per capita consumption of water resources continues to rise at its current rate, humankind could be using over 90% of all available freshwater within 25 years, leaving just 10% for the rest of the world's species (106, 187). What Can Be Done?Caught between growing demand for freshwater on one hand and limited and increasingly polluted supplies on the other, many countries face difficult choices. Finding solutions requires responses at local, national, and international levels-a "Blue Revolution" that focuses on integrated management of watersheds and shared water basins (104) (see Population Reports, Solutions for a Water-Short World, Series M, No. 14, September 1998). Community-led initiatives to manage water resources better can help urban dwellers gain access to safe, piped water supplies, thus improving sanitation and public health (46, 119). Governments can develop national water management policies that not only improve supply but also manage demand better with appropriate pricing—for example, ending subsidies that in effect encourage overuse (221). |