The East Asian economic turmoil of 1997 and its lingering effects belie the decade of unprecedented economic growth in the Southeast Asian region. This economic boom saw a significant increase in the per capita income of the population of the respective countries and a corresponding rise in the standards of living. The decade also saw increased government spending on infrastructural development of basic amenities, including irrigation extension and rural water supply. The demand for and consumption of water increased significantly in both cities and the rural areas. In contrast to the escalating demand for water by the economies of the Southeast Asian countries, available resources remain limited despite the fact that the region generally receives more rainfall than it loses through evaporation annually. Annual, seasonal, and spatial variations in the rainfall within and between countries on the one hand, and accelerated demands for water from the various sectors of the economy on the other, put a severe strain on the available water resource base. In addition, natural resources in the form of rivers, groundwater storage, and lakes are rapidly diminishing in quality as a result of domestic, agricultural, and industrial waste discharges. In the coastal plains, excessive groundwater abstraction resulting in salt-water intrusion has affected groundwater resources. Inland, and in the watershed areas, rapid and extensive development has been at the expense of forested land, which has given way to new urban centres and residential and industrial complexes, while uncontrolled logging and shifting agriculture have caused the deterioration of the remaining forested ecosystem and natural watersheds. Given these factors, the future water resources scenario of the region seems bleak unless urgent steps are taken to manage seriously the resources in a judicious and sustainable way. Water will certainly feature as an important issue of development in the region in the decades ahead, given that large population concentrations and economic development are located in the lower parts of river basins. This chapter describes the hydrological conditions of the Southeast Asian region and examines the nature and extent of water resources that have been put to use for rural and agricultural development.
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