Spate irrigation, a floodwater harvesting and management system, has for the past 70 centuries provided a livelihood for about 13 million resource-poor people in some 20 countries. Despite being the oldest, the system still remains the least studied and the least understood. It is only in the past two decades that the system has been subject to some modernization interventions, much of which focused on improving floodwater diversion efficiency. Effective floodwater diversion measures are necessary, but they must be supplemented with equally effective field water management and soil moisture conservation measures if sustainable improvement of land and water productivity is to be achieved. This paper draws on studies conducted in the past 5 years, particularly in the Republic of Yemen, Pakistan and Eritrea. The studies employed both qualitative and quantitative methods and assessed the modernization package that could result in lasting enhancement of crop productivity in spate irrigated agriculture. The suggested modernization measures include: avoid overstretching the command area; limit the number of irrigation turns to two or an irrigation gift of 1000 mm; avoid field bund heights of more than 1 m; adopt a field-to-field water distribution system instead of an individual field water distribution system; opt for water rights and rules that entitle downstream fields to the more frequent small and medium floods thereby ensuring equity in both water quality and quantity; optimize soil water-holding capacity and infiltration rate through pre-and-post irrigation tillage, combined tillage as well as soil mulching.

One critical problem confronting mankind today is how to manage the intensifying competition for water between expanding urban centres, traditional agricultural activities and in-stream water uses dictated by environmental concerns. In the agricultural sector, the dwindling number of economically attractive sites for large-scale irrigation and drainage projects limits the prospects of increasing the gross cultivated area. Therefore, the required increase in agricultural production will necessarily rely largely on a more accurate estimation of crop water requirements on the one hand, and on major improvements in the construction, operation, management and performance of existing irrigation and drainage systems, on the other. The failings of present systems and the inability to sustainably exploit surface and groundwater resources can be attributed essentially to poor planning, design, system management and development. This is partly due to the inability of engineers, planners and managers to adequately quantify the effects of irrigation and drainage projects on water resources and to use these effects as guidelines for improving technology, design and management.To take full advantage of investments in agriculture, a major effort is required to modernize irrigation and drainage systems and to further develop appropriate management strategies compatible with the financial and socio-economic trends, and the environment. This calls for a holistic approach to irrigation and drainage management and monitoring so as to increase food production, conserve water, prevent soil salinization and waterlogging, and to protect the environment. All this requires, among others, enhanced research and a variety of tools such as water control and regulation equipment, remote sensing, geographic information systems, decision support systems and models, as well as field survey and evaluation techniques. To tackle this challenge, we need to focus on the following issues:• affordability with respect to the application of new technologies;• procedures for integrated planning and management of irrigation and drainage systems; • analysis to identify causes and effects constraining irrigation and drainage system performance;• evapotranspiration and related calculation methods;• estimation of crop water requirements;• technologies for the design, construction and modernization of irrigation and drainage systems; • strategies to improve irrigation and drainage system efficiency;• environmental impacts of irrigation and drainage and measures for creating and maintaining sustainability;

In the coming decades population growth will take place particularly in the emerging and least developed countries. This implies that these countries will be confronted with the need to increase their food supply by a larger production in their own territory, maybe in combination with increased imports. With respect to the required increase in food production in combination with the need for sustainable rural development a wide range of issues is of importance. From the point of view of food production there is a common feeling that 90% of the required increase will have to be realised on existing cultivated land and 10% on newly reclaimed land. From the point of view of sustainable rural development, socio-economic and environmental aspects play crucial roles.In this paper the focus is on how improvements in water management may contribute to the developments that may be expected. This is discussed in light of population growth and illustrated with the global distribution of the production of cereals and rice. Within this framework the different means of water management that may contribute to the required increase in food production and sustainable rural development are presented. With respect to this it is, among others, of importance that at large scale irrigation management transfers are taking place in the emerging countries and in countries with a transition economy. Copyright # 2005 John Wiley & Sons, Ltd.key words: irrigation; drainage; sustainable development; networking system RÉ SUMÉ Les prochaines décennies seront témoins d'une croissance démographique dans les pays en développement qui émergent et les moins développés. Cela signifie que ces pays seront affrontés par la nécessité d'accroître leur approvisionnement alimentaire en ayant recours à une production accrue dans leur propre territoire, peut être simultanément avec les importations. Compte tenu de la nécessité d'augmenter la production alimentaire simultanément avec la nécessité de développement rural durable, l'on estime qu'un large éventail de questions d'importance y intervient. Du côté de production alimentaire, l'on constate généralement qu'il est nécessaire de réaliser une augmentation de 90% sur les terres cultivées existantes, et de 10% sur les terres mises en valeur. Du côté du développement rural durable, les aspects socio-économiques et environnementaux jouent des rôles d'une importance cruciale.Le rapport tient à préciser comment l'amélioration de la gestion d'eau peut contribuer au développement escompté. Cet aspect y est discuté compte tenu de la croissance démographique, en même temps que les explications sur la distribution des céréales et du riz au niveau global. Dans ce cadre, l'auteur présente différentes méthodes de gestion des eaux qui puissent contribuer à l'augmentation de production alimentaire requise et au développement rural durable. A cet égard, il convient de mentionner parmi d'autres, qu'un grand nombre de transmissions de gestion des eaux est effectué dans les pays qui émergent et dans les pays à économi...

The development and management of irrigation, drainage and flood protection schemes are confronted with rapidly changing conditions, especially in the least and emerging developing countries. Issues at stake are the need to increase food production significantly, the development of water shortages, pollution of water resources, the increased requirement for flood management and flood protection schemes, the need for sustainable development and possible impacts of climate changes.In this paper focus is on how these issues may play a role in the development of irrigation, drainage and flood protection measures and schemes under different climatological and socio-economic conditions. KEY WORDS: population growth; food production; irrigation; drainage; flood protection; sustainability; climate change RÉ SUMÉ Le développement et la gestion des systèmes de l'irrigation, du drainage et de la maîtrise des crues sont confrontés aux conditions rapidement changeantes, spécialement dans les pays les moins développés et ceux en voie de développement surgissant. Les affaires d'importance sont la nécessité de l'augmentation significative de la production alimentaire, l'augmentation des manques de l'eau, la pollution des ressources, les exigences pour les schémas de la maîtrise des crû es et le besoin de développement durable et des impacts possibles des changements du climat.Dans ce papier l'attention est fixée sur le fait comment les affaires en question peuvent jouer un rôle dans les mesures et les schémas du développement de l'irrigation, du drainage et de la maîtrise des crues sous des conditions climatologiques et socio-économiques différentes. Conformément à cela la Stratégie pour Action de la Commission Internationale des Irrigations et du Drainage (CIID) est présentée, montrant quelles contributions la CIID donne et quelles contributions elle a l'intention de donner en réponse aux défis. Copyright © 2001 John Wiley & Sons, Ltd. MOTS CLÉ S: l'augmentation de la population; la production alimentaire; l'irrigation; le drainage; la maîtrise des crues; les solutions durables; des changements du climat

No abstract