World distribution of water resources and utilizations: present and future disparities

Water resources are very irregularly distributed through the world, and so is their utilization, both between countries and between users within countries. Tables and maps describing this variety can be drawn up using available statistics and the macroscopic indicators derived from them. Water resources depend upon the climates that generate them and the physiographic structures that distribute them. Their utilization also varies according to climate, but depends in addition upon the degree of development of the country concerned. Resources vary, per head of population, in the ratio 1:1000, and utilization in the ratio 1:100. These inequalities are likely to be aggravated in the future. The rapid decrease in physical resources per head of population caused by demographic growth risk in some instances limiting the possibility of satisfying the increasing requirements caused by the pressures of development, or at least strongly accentuating the artificialization of the terrestrial stages of the water cycle in certain regions.