ABSTRACT

There are nearly 40,000 large dams in the world, increasing around 250 a year. More reservoirs need to be built, in developing countries, for anticipated population growth, upgrading standard of living, urbanization, flood control, hydroelectric energy, and so on. In developed countries, however, instead of reservoir construction, more emphasis will be placed on demand management and efficient use and reuse of water to meet higher environmental quality needs. Climate change would increase the importance of reservoirs but societal adaptation measures should precede the physical counteractions. The average sedimentation rate to fill reservoirs in the world may not be very high, but the rate is much higher in East and Southeast Asia where many reservoirs would suffer from sedimentation problems in the latter part of the twenty-first century. Reservoirs are the most important component for risk and uncertainty management of water resources systems. But for a reliable and robust water resources system, an integrated management and the administrative structure that makes it possible are most important. The integrated management is also the key strategy for sustainable reservoirs and water resources management.

INTRODUCTION

Reservoirs are indispensable to utilize running water for sustaining life and civilized activities. They must have been built ever since the beginning of human history and clearly since the emergence of irrigated agriculture. The oldest ruin of a dam may be the Sad el-Kafara Dam, 30km south of Cairo, Egypt (length 104m, height 11m and storage capacity 0.57 · 106m3), that was built around 2800 B.C. for water supply, and believed to be destroyed by the first hit of a flood (Biswas 1970).