Overview on Global Water Resources

Abstract

The oceans are the Earth’s primary conventional storage body for water, including the Antarctic, Arctic and glaciers of high mountain peaks. The groundwater represents 29.9%, and only 0.26% of the total freshwater is stored in lakes, rivers and reservoirs while 0.94% is soil moisture. The water available for direct human use comprises 96.80% groundwater, 0.02% river water and 3.18% in lakes, while desalinated water and treated wastewater are the main nonconventional sources of water. The rapid increase in population between 1970 and 2014 lowered the per capita water share from 12,900 m3 in 1970 to 5926 m3 in 2014. The main global water challenges are the uneven distribution of water resources, water-quality problems, escalating demands and climate change. The MENA region is about 8% of the world’s area, inhabited by 5% of the world’s population, but its water resources do not exceed 1% of the Earth’s water. The number of countries suffering from water shortage is expected to reach 18 in 2025. The annual per capita water share is > 2000 m3 in Iran and Iraq and <200 m3 in Yemen, Jordan, Bahrain, Libya and most of the Gulf Cooperation Council (GCC) countries. About 15% of the world population receives more than 50% of its water resources from neighboring countries, which is called international water, and many areas will witness future disputes over such shared water. The annual renewable, conventional water resources in the Arab region are estimated at 338 Bm3 , of which 296 Bm3 is surface water, 42 Bm3 groundwater recharge and 15,000 Bm3 is nonrenewable water resources. In 2035, the annual average per capita share of natural water resources in the Arab region is predicted to reach 464 m3 . The water problems in the Arab countries are overexploitation of groundwater resources, lack of integrated water-resources management, natural variability, uncoordinated utilization of shared-water resources and water pollution. The share of the GCC countries of total water resources in the Arab region is 4.6%. The total water resources in the Arabian Gulf countries between 1988 and 1997 reached 10.31 Bm3 , including 8.00 Bm3 of conventional and 2.31 Bm3 of nonconventional resources, while, water demand will reach about 32.23 Bm3 by 2025. The average annual water consumption of individuals in the GCC countries region is 1035 m3 /year, while the per capita share of natural water resources is less than 250 m3 /year, which is 50% less than the recognized water-scarcity limit (500 m3 /year).