Of all the confrontations man has engineered with nature, irrigation systems have had the most widespread and far-reaching impact on the natural environment. Over a quarter of a billion hectares of the planet are irrigated and entire countries depend on irrigation for their survival and existence. Considering the importance of irrigation schemes, it is unfortunate that until recently the technology and principles of design applied to their construction has hardly changed in 4,000 years. Modern thinking on irrigation engineering has benefited from a cross-fertilization of ideas from many other...