Introduction
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This program responds to the need to raise awareness to the advantages and limitations of various design criteria for canal irrigation systems used in many countries and to disseminate information on advanced approaches to canal operation developed since the mid 1950's. The program focuses on systems and methods that minimize dependence on overly complex management procedures while at the same time maximizing efficiency of water use and reliability of irrigation service to users and alleviating environmental effects. The first edition of that program was produced in English and French languages in 1988, as a joint effort of the Economic Development Institute (now known as the World Bank Institute) and the Agricultural and Rural development Department of the World Bank. In the early 1990s a Spanish version on videotapes was produced by IMTA, the Mexican Institute for Water Technology. A version in Turkish language was also produced by DSI from Turkey in 2000. These versions in different languages were used by consulting firms and Universities in many countries to present new alternative solutions for the design of new projects or the modernization of existing projects. During the last 15 years, a number of countries have adopted some elements of modern design standards for new or rehabilitation projects, at full or pilot scale. For example, in a number of countries, the replacement of gated cross-regulators by long-crested weirs is becoming accepted as a new design practice and well appreciated by the water users for its impact on the reliability of the irrigation service. A number of modern pilot projects, with advanced design, some using sophisticated remote control have been implemented in a number of countries. Together with the efforts of other irrigation organizations, this program may have contributed to the progressive acceptance of new approaches to design of irrigation systems. Progress however is still slow and considerable effort are needed to improve the performance of the gravity irrigation systems which account for about two-thirds of the presently irrigated areas in the world. In 2001, the program was transferred to the Department of Land and Water in FAO, which decided to update the information contained in the program. About 15 years have passed since the first edition. A large part of the program, such as the presentation of the conventional design approaches and the modern irrigation control strategies are still valid. Most of the innovations during the last 15 years concern water measurement equipment, electronic-based equipment for local and remote control and for telecommunications. Furthermore considerable changes have been made in some countries in the management of irrigation projects through institutional reforms aiming at increased participation of the users through devolution of management to user organizations or participation in the decision process. Modernization of irrigated agriculture has been the theme of numerous seminars, workshops and conferences during the last 15 years. It is no longer understood as the adoption of sophisticated techniques based on the use of advanced computer modeling and means of communications. The definition adopted in a FAO seminar in Bangkok in 1996 is the base of this training material: "Modernization is a process of improving resource (labor, water, economic, and/or environmental) utilization through upgrading (as opposed to mere rehabilitation) of the hardware and software of irrigation projects, while maintaining or improving water delivery service to farms". Irrigation modernization involves institutional, organizational and technological changes. This program deals essentially with the technological changes either for development of new irrigation projects or rehabilitation of existing ones. Its ultimate objective is to improve service to the users and improve the sustainability of irrigated agriculture. This second edition reflects the progress in technology made during the last fifteen years, in particular in water measurements, in communications and electronic equipment. It also reflects the new approaches to user participation in the management of irrigation systems and the recent experiences of countries, such as Mexico, Turkey, India and Nepal. Three new topics therefore are developed in this second edition:
The use of modern design standards and equipment is not however is a guarantee of success. The failure of few pilot projects is a step backward in the acceptance of modern design and provides arguments to the proponents of modernization. Successful modernization requires higher standards of design and construction. It also requires training of operation staff to the new operational procedures. This program attempts to distill and summarize current information on canal irrigation and to present it as simply as possible in an effort to reach a broad audience ranging from planners and design engineers to agronomists and project managers. Treatment of the topic is necessarily limited. Some may find the presentation to be too theoretical, while others may consider it too simplistic. This risk is implicit in nay attempt to communicate a comprehensive body of knowledge to a diverse readership. This program is therefore not the equivalent of a design manual. Those interested in gaining a deeper understanding of the topics should refer to:
This essentially technical program does not address the broad range of policy tools that could improve the productivity of irrigation water. It is however stressed here that it is the combination of physical changes with policy and institutional reforms that yield the best improvements in irrigation management. Water-saving incentive tools, such as volumetric pricing and the establishment of tradable water rights, cannot be implemented without an adequate delivery system.
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