Most of the world irrigation systems were developed on a step-by-step basis, over the centuries, and were designed for a long life (50 years or more), on the assumption that climatic conditions would not change in the future. This will not be so in the years to come due to the global warming and greenhouse effect. Therefore, engineers and decision makers need to systematically review planning principles, design criteria, operating rules, contingency plans and management policies for new infrastructures. In relation to these issues and based on available information, the report gives an overview of current and future (time horizon 2025) irrigation development around the world. Moreover, the paper analyses the results of the most recent and advanced General Circulation Models for assessing the hydrological impacts of climate variability on crop requirements, water availability, food security and the planning and design process of irrigation systems. Finally, a five-step planning and design procedure is proposed able to integrate, within the development process, the hydrological consequences of climate change | [A livello mondiale, la maggior parte dei sistemi di irrigazione è stata sviluppata gradualmente, nel corso dei secoli ed è stata progettata per lunghi periodi (50 anni o più) in base al presupposto che le condizioni climatiche non sarebbero cambiate in futuro. Questo non sarà più vero per i prossimi anni, per effetto del riscaldamento globale e dell'effetto serra. Perciò, i tecnici e i politici devono rivedere sistematicamente i principi di programmazione, i criteri di progettazione, le norme operative, i pianti di emergenza e le politiche di gestione per le nuove infrastrutture. In relazione a queste questioni e in base alle informazioni disponibili, il contributo fornisce una panoramica dello sviluppo presente e futuro (orizzonte temporale al 2025) dello sviluppo dell'irrigazione a livello mondiale. Inoltre, il lavoro analizza i risultati dei Modelli di Circolazione Generale più recenti e avanzati per determinare gli impatti idrologici della variabilità climatica sulle esigenze delle coltivazioni, la disponibilità di acqua, la sicurezza alimentare e il processo di programmazione e progettazione dei sistemi di irrigazione. Infine, viene proposta una procedura di programmazione e progettazione a cinque fasi, in grado di incorporare nel processo di sviluppo le conseguenze idrologiche del cambiamento climatico]

This book, which contains 13 separately authored chapters, has been developed from the ADAPT Project, focusing on the development of regional adaptation strategies to climate change and climate variability for water, food and the environment in river basins across the world. Chapter 1 describes a generic methodology for river basins (called the Adaptation Methodology for River Basins, AMR). Chapter 2 discusses the use of climate change scenarios as provided by the Intergovernmental Panel on Climate Change and, more specifically, how these scenarios can be used for regional studies. Chapters 3 and 4 describe in more detail the possible consequences of climate change and climate variability for food security and environmental quality. The application of the generic AMR methodology to 7 basin case studies in contrasting geographical areas of the world is presented in Chapters 5-11: Syr Darya (Kyrgyzstan, Uzbekistan, Tajikistan and Kazakhstan), Zayandeh (Iran), Rhine (Germany, Netherlands and France), Mekong (Yunnan (China), Myanmar, Laos, Thailand, Cambodia and Vietnam), Volta (Ghana), Walawe (Sri Lanka), and Sacramento (California, USA), respectively. Chapter 12 integrates the findings of the basin studies and compares these findings with global trends in climate change related to food security. Finally, Chapter 13 gives a summary of the experiences encountered during the ADAPT project, and provides key findings that should be addressed in new regional adaptation studies. This book will be of interest to researchers in climatology, geography, ecology, agriculture, environmental studies and related disciplines. | Gift

At first glance, it appears that the region is well endowed with water resources. While accounting for only about 16 percent of the world's land surface, it receives 22 percent of its precipitation and produces 28 percent of its renewable water resources. However, the region is home to 53 percent of the world's population and its IRWR [internal renewable water resources] are only about half of the world's average. By and large, most countries in Asia (except for Singapore, Maldives and Republic of Korea) are still not considered water-stressed. However, even in countries with high level of per capita water availability, large segments of the population are beset with water scarcity as a result of the large variations in the spatial and temporal distributions of rainfall and stream flow. About 84 percent of the total water withdrawal of the region is for agriculture. Irrigation accounts for the bulk of water use in agriculture due to the large irrigation base and the fact that approximately half of the irrigated area is devoted to flooded rice production. Although still relatively small in most Asian countries, the industrial, municipal and environmental demands for water continue to increase at a rate twice that of population growth. The proportion of water available for agriculture is projected to decline to 62 percent worldwide and 73 percent in developing countries by 2020. Hence, the opportunities for expanding the irrigation base are limited. If food security is to be maintained, ways of increasing water productivity must be found. A host of interrelated issues must be addressed in the short-and-medium terms if a water crisis in the region is to be averted. Among others, these include: changing demand patterns, impact of climate change and watershed modifications on dependable water supply, low water productivity in agriculture,in adequate investments in water supply systems to meet future demands, a shift toward decentralized and privatized water service and market mechanisms, the need to reduce non-revenue water, sustaining and expanding the irrigation base, recycling wastewater for agriculture, access to water of the rural and urban poor, groundwater mining, the need to strengthen international collaboration for managing shared water resources, protection of freshwater ecosystems, and fostering a favorable environment for a comprehensive water resources policy and program frameworks. The specific issues in irrigation that are more pressing were discussed. Suggestions on how to address these issues were presented. Two very significant changes in irrigation development policy and strategy in many developing countries of Asia were discussed. First is the shift from large, gravity irrigation systems towards small privatized farmer-controlled irrigation systems such as shallow tubewells, low-lift pumps, farm reservoirs and diversion dams. Second is the dramatic shift from the virtual monopoly of the central role of national government towards greater participation of other players such as WUAs [water users association], NGOs [non governmental organizations], and local government units. The public sector activities are now focused on improving the management of water at the main system level and adopting new policies aimed at creating incentives for WUAs or cooperatives to take over the O and M [operation and management] of the rest of the irrigation facilities.