World Water Resources at Stake

Abstract

Overviews on the basic human needs on water and world water withdrawals are introduced, and the reason why we should concern on the availability is explained by its uneven distribution seasonally and geographically. The relationship between human society and water is also illustrated with an example of the dawn of civilization why all of them are located in semi-arid regions downstream of moderately large rivers, not gigantic rivers, with their head waters in wet region. The global estimates of withdrawals for irrigation and artificial reservoirs to support the stable supply of water, and their impacts on sea-level rise or suppress are discussed. The special characteristics of water compared to energy and food are articulated and the reason why water-intensive commodities, such as food, are traded internationally as “virtual water trade”, instead of water itself is elucidated.