Enhancing Irrigation Water Productivity

First title in a major new seriesAddresses improving water productivity to relieve problems of scarcity and competition to provide for food and environmental securityDraws from scientists having a multitude of disciplines to approach this important problemIn a large number of developing countries, policy makers and researchers are increasingly aware of the conflicting demands on water, and look at agriculture to be more effective in its use of water. Focusing on both irrigated and rain-fed agriculture, this book gives a state of the art review of the limits and opportunities for improving water productivity in crop production. It demonstrates how efficiency of water use can be enhanced to maximize yields. The book represents the first in a new series of volumes resulting from the Comprehensive Assessment of Water Management in Agriculture, a research program conducted by the CGIAR's Future Harvest Centres, the Food and Agriculture Organization of the United Nations and partners worldwide. It will be of significant interest to those working in areas of soil and crop science, water management, irrigation, and development studies.

Water a key natural resource, fundamental to life, livelihood, food security and sustainable development is rapidly becoming scarce and limited. Agriculture is the major water user in our country utilizing nearly 70-80 per cent of all the utilizable water resources of the country. Therefore, Agricultural Water Management (AWM) interventions aim at enhancing per capita benefits, while preventing the degradation of natural resource bases of land, water and ecosystem services. Evidence shows that AWM interventions have increased yields, which has helped areas with low productivity. In recent past a large number of new techniques and advanced tools have been invented in recent past which can enhance the water productivity in agriculture to a very high level. Knowledge adoption and extensive use of these tools and techniques needs proper dissemination. There is a dearth of ample number of technically trained manpower to undertake the work of On-farm AWM. Therefore, the present book has been organized with following specific objectives: i) to impart the advanced knowledge of On-farm water management using modern concepts, tools and techniques for assessing, planning and designing the AWM (irrigation and drainage) systems and to disseminate these techniques for enhancing crop water use efficiencies; ii) to train the readers in designing, installation operation and automated operation, controls and management of high-tech irrigation water management systems; and iii). to provide the participants an opportunity to discuss and exchange the new ideas/knowledge with experts/resource persons who have contributed substantially in Agricultural Water Management (AWM). The book has a very wide spectrum covering almost all topics pertaining to advanced concepts and methods of modern Agricultural Water Management. The present book will provide to the readers an in-depth understanding of various related topics pertaining to highly efficient irrigation water management for crop production and enhancing agricultural water productivity such as scientific design and layout of farm irrigation and drainage, soil water content measurement using TDR/Neutron Moisture meters/Soil moisture probe, geophysical techniques of groundwater exploration etc. It will elaborate the concepts and methodology of using modern instruments and systems of irrigation such as drip, sprinkler, rain gun, level basin system etc. that would be an added benefit. Applications of modern techniques such as GIS and remote sensing applications for enhancing water resources use efficiencies in irrigation project, sensor based weather data collection and automated irrigation management and control systems under open field and covered cultivation have been explained in depth. The book shall impart the comprehensive knowledge on advanced concepts in Soil-Plant-Climate interactions, scientific estimation of crop water demand, various irrigation scheduling criterions and application of modern tools and techniques such as; application of computer softwares (such as EQUITA/DRIPD/CROPWAT/AQACROP/IMPASSE/USAR etc.) for irrigation planning and management; under different water supply scenarios in a lucid manner.

The role of irrigation in gearing agriculture development towards a broader economic growth is undeniable. Accordingly, irrigation is growing into key operational strategy for governments and their agencies to increase agricultural productivity, thus combatting food insecurity and boosting overall growth. While agriculture absorbs rural workforce, generates income and increases food security, it has become the most important driver in freshwater exploitation. The rapid expansion of water demand leads to the generalized phenomena of imbalance between water supply and water demand. This increasing pressure on water resources urges enhancing Water Use Efficiency. Enhancing Water Use Efficiency requires actions at all levels, from agricultural practitioners to scheme managers, and up to the policy-makers. The objective of this Field Guide is to show practical measures to improve Water Use Efficiency in small-scale agriculture based on case studies from Burkina Faso, Morocco and Uganda. The Book not only presents applicable Water Use Efficiency measures, but also guide the readers through their real-term implementation. While the Guide provides complete set of instructions to improve Water Use Efficiency in order to reach optimal irrigation practices, the successful outcome still depends on the farmers’ willingness to embrace and adopt the recommended measures. The Guide holds in evidence that farmers are often constrained by available resources to improve their practices in terms of budget, inputs or labour. In order to take these issues into account, the recommendations are limited on practical measures, which can be followed by farmers without requiring additional resources.

The management of irrigation systems is context-dependent, socially constructed, and technically uncertain. An example of complex social-ecological systems, irrigation deals with both the ecosystem uncertainty and the implementation of new technological systems and water management options. Issues to be addressed by irrigation systems at the global scale include: water productivity and food security, field operation and maintenance, spate irrigation in climate change scenarios, and vulnerability of environmental resources. This book provides examples of some of the current challenges faced by irrigation systems from technical and social perspectives. The book offers an easy-to-follow format focused on different case studies combining evidence-based solutions for increasing resilience and reducing vulnerability of irrigation systems in semi-arid and arid regions across the world.

This technical document contains clear and practical guidelines on how to implement real water savings in agriculture through interventions for enhancing crop water productivity. A distinction is made between real water savings and “apparent” water savings. Apparent water savings record reductions in water withdrawals but do not account for changes in water consumption. Real water savings record reductions in water consumption and non-recoverable return flows (runoff or percolation). This guidance document emphasizes the paradox of water savings at field and basin scales, which usually do not translate into increased water availability for other users, as is commonly believed.

*First title in a major new series *Addresses improving water productivity to relieve problems of scarcity and competition to provide for food and environmental security *Draws from scientists having a multitude of disciplines to approach this important problem In a large number of developing countries, policy makers and researchers are increasingly aware of the conflicting demands on water, and look at agriculture to be more effective in its use of water. Focusing on both irrigated and rain-fed agriculture, this book gives a state of the art review of the limits and opportunities for improving water productivity in crop production. It demonstrates how efficiency of water use can be enhanced to maximize yields. The book represents the first in a new series of volumes resulting from the Comprehensive Assessment of Water Management in Agriculture, a research program conducted by the CGIAR's Future Harvest Centres, the Food and Agriculture Organization of the United Nations and partners worldwide. It will be of significant interest to those working in areas of soil and crop science, water management, irrigation, and development studies.

Over the past decade, we have witnessed a growing scarcity of and competition for water around the world. As the demand for water for domestic, municipal, industrial, and environmental purposes rises in the future, less water will be available for agriculture. But the potentials for new water resource development projects and expanding irrigated area are limited. We must therefore find ways to increase the productivity of water used for irrigation. This paper reviews the literature on irrigation efficiency and on the potential for increasing the productivity of water in rice-based systems. It stresses the continuing confusion over the concepts of irrigation efficiency and water productivity. It identifies the reasons for the wide gap between water requirement and actual water input (both irrigation diversions and rainfall) in irrigated rice production systems and discusses potential opportunities for increasing water productivity both on-farm and at the system level. Based on the reported low farm and system level irrigation efficiencies, the potentials for water savings in rice production appear to be very large. But we do not know the degree to which various farm and system interventions will lead to sustainable water savings in the water basin until we can quantify the downstream impact of the interventions. Studies on the economic benefits and costs, and environmental aspects of alternative interventions are also lacking. This paper emphasizes the need to measure the productivity of water at farm, system, and basin levels, and to understand how the productivity at one level relates to the productivity at another. Without water balance studies to measure productivity at these different scales, it is not possible to identify the potential economic benefits of alternative interventions and the most appropriate strategies for increasing irrigation water p productivity in rice-based systems.