INTRODUCTION

One of the dramatic shifts of modern public opinion with regard to water and environmental policy during the twentieth century involved dams and reservoirs. The technology of dam construction has ancient origins, dating from small brush diversions of water in many regions of the world to the famous large stone dam at Marib, Yemen, which is believed to have been initiated three millennia ago in a region of floodwater farming (Brunner, 2000; Brunner and Haefner, 1986). After reaching a height of about 15 m, length of 720 m, and basal width of 60 m, earthquakes contributed to a catastrophic breach in the early seventh century CE, a disaster ascribed to divine disfavor in the Qur'an:

The abutments of Marib Dam still stand, as do those of a very large embankment dam at Saad-El-Katara, Egypt, which was begun but apparently not completed in the third millennium BCE (Garbrecht, 1996).

By 2000, the International Commission on Large Dams (ICOLD, 1998) estimated that some 45,000 “large dams” (greater than 15 m high) had been built around the world, almost half of them in China.