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.

Description of thirappane cascade; Hydrological modeling of TCS; Groundwater movement in meegassagama command area; Optimal cropping mixture and water management; Discussion and recommendations.

nadequate funding for maintenance of irrigation works and emerging shortages of water are prevalent. The use of water charges to generate resources for maintenance and to reduce demand is widely advocated. Examples from other utilities, and from the domestic/industrial sectors of water supply suggest the approach could be effective. In developing countries, the facilities required for measured and controlled delivery of irrigation are rarely in place, and would require a massive investment in physical, legal and administrative infrastructure. To be effective in curtailing demand, the marginal price of water must be significant. The price levels required to cover operation and maintenance (O&M) costs are too low to have a substantial impact on demand, much less to actually bring supply and demand into balance. On the other hand, the prices required to control demand are unlikely to be within the politically feasible range. Furthermore, water supplied is a proper measure of service in domestic and industrial uses. But in irrigation, and especially as the water resource itself becomes constrained, water consumption is the appropriate unit for water accounting. This is exceptionally difficult to measure. An alternative approach to cope with shortage would focus on assigning volumes to specific uses–effectively rationing water where demand exceeds supply. This approach has a number of potential benefits including simplicity, transparency, and the potential to tailor allocations specifically to hydrological situations, particularly where salinity is a problem. Data from Iran are presented to support these contentions.

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.

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.

In this report, the concept and procedures of hydronomic (hydro water + nomus management) zones are introduced. A set of six hydronomic zones are developed and defined based on key differences between reaches or areas of river basins. These are the: Water Source Zone, Natural Recapture Zone, Regulated Recapture Zone, Stagnation Zone, Final Use Zone, and Environmentally Sensitive Zone. The zones are defined based on similar hydrological, geological and topographical conditions and the fate of water outflow from the zone. In addition, two conditions are defined which influence how water is managed: whether or not there is appreciable salinity or pollution loading; and whether or not groundwater that can be used for utilization or storage is present. Generic strategies for irrigation for four water management areas, the Natural Recapture, Regulated Recapture, Final Use, and Stagnation Zones, are presented. The Water Source Zone and Environmentally Sensitive Zone are discussed in terms of their overall significance in basin water use and management.

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.

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.

As water availability, management and conservation become global challenges, there is now wide consensus that historical knowledge can provide crucial information to address present crises, offering unique opportunities to appreciate the solutions and mechanisms societies have developed over time to deal with water in all its forms, from rainfall to groundwater. This unique collection explores how ancient water systems relate to present ideas of resilience and sustainability and can inform future strategy. Through an investigation of historic water management systems, along with the responses to, and impact of, various water-driven catastrophes, contributors to this volume present tenable solutions for the long-term use of water resources in different parts of the world. The discussion is not limited to issues of the past, seeking instead to address the resonance and legacy of water histories in the present and future. Water and Society from Ancient Times to the Present speaks to an archaeological and non-archaeological scholarly audience and will be a useful primary reference text for researchers and graduate students from a variety of disciplinary backgrounds including archaeology, anthropology, history, ecology, geography, geology, architecture and development studies.

This report analyzes the history of groundwater development in the eastern Uttar Pradesh region over the 1950-1990 period. Its main conclusion is that the story of groundwater-based livelihood creation in the Ganga basin is one of failed public initiatives and successful adaptive responses by private agents. However, tube-well-induced agrarian dynamism in eastern Uttar Pradesh and north Bihar in recent years can spread to the entire basin if public policy makers learn correct lessons from the experience of these two subregions.