Studies the low-cost alternative strategy of selective lining of watercourses to reduce seepage and increase irrigated areas in the Indian subcontinent. Satellite remote-sensing (SRS) is seen as a cost-effective evaluation tool in view of its large area of synoptic and repetitive coverage.
A clear understanding of the current water balance is required to explore options for water saving measures. However, measurement of all the terms in the water balance is infeasible in terms of spatial and temporal scale, but hydrological simulation models can fill the gap between measured and required data. For a basin in Western Turkey, simulation modeling at three different scales, field, irrigation scheme and basin scale, was performed to obtain all terms of the water balance. These water balance numbers were used to calculate the Productivity of Water at the three spatial levels distinguished to assess the performance of the systems.
This volume is an analytical summary and a critical synthesis of research at the International Water Management Institute over the past decade under its evolving research paradigm known popularly as 'more crop per drop'. The research synthesized here covers the full range of issues falling in the larger canvas of water-food-health-environment interface. Besides its immediate role in sharing knowledge with the research, donor, and policy communities, this volume also has a larger purpose of promoting a new way of looking at the water issues within the broader development context of food, livelihood, health and environmental challenges. More crop per drop: Revisiting a research paradigm contrasts the acquired wisdom and fresh thinking on some of the most challenging water issues of our times. It describes new tools, approaches, and methodologies and also illustrates them with practical application both from a global perspective and within the local and regional contexts of Asia and Africa. Since this volume brings together all major research works of IWMI, including an almost exhaustive list of citations, in one single set of pages, it is very valuable not only as a reference material for researchers and students but also as a policy tool for decision-makers and development agencies.
Discusses and illustrates concepts for identifying ways of improving productivity of water within basins. The results of applying a water accounting procedure to four sub-basins in South Asia (Bhakra in India; Chishtian in Pakistan; Huruluwewa in nothern Sri Lanka; and Kirindi Oya in southern Sri Lanka) are presented. The methodology used identifies the quantities and productivity of various uses of water within a basin. This information is then used to identify the water-saving potential, and the means of improving the productivity of the managed supplies.
Better water management in irrigation tank cascade systems is vital in achieving higher productive use of available water. To develop and implement management practices aimed at improving effective use of water, studies leading to the development of models that can predict available tank water in irrigation tank cascade systems are invaluable. This report presents a simple water balance model, Cascade, developed to predict tank water availability in the Thirappane tank cascade system in Anuradhapura, Sri Lanka. The report includes calibration of the model and its application to predict tank water availability for rice crops over a 10-year period.
Describes the use of a distributed hydrologic model to evaluate different data scenarios. The study attempted to answer questions such as; what will happen to the basin water resources if a) there is a change in climate; b) it is decided that more water must be retained in the river for environmental reasons; c) more water is extracted for urban and industrial use; d) the timing and accounts used for water are changed?
Although irrigation projects often provide water for more than crop irrigation, water allocation and management decisions often do not account for nonirrigation uses of water. Failure to account for the multiple uses of irrigation water may result in inefficient and inequitable water allocation decisions. Decision-makers often lack information on the relative economic contributions of water in irrigation and nonirrigation uses. This report addresses this problem. It examines the relative economic contributions of irrigated agriculture and reservoir fisheries in the Kirindi Oya irrigation system, located in Southeastern Sri Lanka. The results of the analysis indicate the importance of both irrigated paddy production and reservoir fisheries to the local economy. They also demonstrate significant potential financial and economic gains to irrigated agriculture from improvements in water management practices. Since these water uses are interdependent, policy makers must consider how changes in water management practices may affect reservoir levels and water quality and the fisheries that depend on them.
Smallholder irrigation systems–where farm sizes generally range from a fraction of a hectare to 10 hectares–pose special management problems, especially where the water available for irrigation is frequently less than the demand. The intensity of system adjustments required to meet individual farmer demands, and the administrative complexity of measuring and accounting water deliveries have generally proven excessive when attempting to meet “on demand†schedules, resulting in chaos (often characterized by illegal tampering with infrastructure, and vast differences of water use intensity at different locations in the system). The alternative–provision of a simple service, based on proportional sharing of available supplies on the basis of landholdings–has been resilient for many years over vast areas. The approach is based on a clear delineation between the part of the irrigation system that is actively managed (at various flow rates and water levels) and the part of the system that operates either at full supply level (with proportional division of water down to the level at which farmers rotate among their individual farms), or is completely shut. This operational design is known as a “structured†system, and has well-defined hydraulic characteristics, simplifying operation and management, in turn allowing a clearer definition of water entitlements and the responsibilities of agency staff and farmers. The approach is particularly suited to areas where water is scarce and discipline is needed to ration water among users. An additional benefit, which has been demonstrated in modeling studies using a well–proven model relating to water and yield, is that the productivity of water (which is more important than the more traditional productivity of land when water is scarce) is substantially increased when deficit irrigation is practiced–a widely observed and predictable response to rationed water supplies. Structured systems are most suited where water is scarce, clear definition of water entitlements is needed, management capacity is limited, and investment resources are limited. The approach to determining critical aspects of a structured system design is described in this report.
Coping with scarcity of water supply for managing irrigation under uncertain and inadequate conditions has become part and parcel of many irrigation systems in the semiarid tropics of Asia. Based on a case study of the Kirindi Oya Irrigation and Settlement Project (KOISP) in southern Sri Lanka, this report provides evidence of the uncertain and inadequate inflow into the reservoir and its impact on the seasonal planning.