Dealing with Water Scarcity in the Next Century by Mark W. Rosegrant Reform of water policy is urgently needed to avert severe national, regional, and local water scarcities that will depress agricultural production and worsen water-related health problems.
Water is abundant globally but scarce locally.
Three-quarters of the freshwater is in glaciers and icebergs, another fifth is groundwater, and less than 1 percent is in lakes and rivers. Almost two-thirds of the renewable freshwater provided by annual rainfall over land evaporates. Much of the rainfall transformed into runoff is lost to floods. Given current global water use of 4,000 cubic kilometers, the remaining 14,000 cubic kilometers of effective runoff would be adequate to meet demand for the foreseeable future if supplies were distributed equally across the world's population. But freshwater is distributed extremely unevenly across countries, across regions within countries, and across seasons.