NEW DIRECTIONS IN WATER RESEARCH: IWMI AT THE THRESHOLD OF THE TWENTY-FIRST CENTURY (pp. 5-16)
Abstract: The International Water Management Institute (IWMI) has made important changes in the thrust of its research programmesince 1995.These new thrusts include attention to the implications of increasing water scarcity at the global level; the adoption of a river basin paradigmleading to new insights into opportunities for water conservation and productivity; application of new information technologies and quantitative analytical techniques; and a stronger focus on policy, institutional issues, health and environment, and social inequities in access to water. This paper describes these changes and provides an overviewof the remaining papers in this special issue of Water Resources Development.
LOOKING AHEAD: WATER, LIFE AND THE ENVIRONMENT IN THE TWENTY-FIRST CENTURY (pp. 17-28)
Abstract: This paper establishes the broad context for the research results reported in this special volume. It explores some of the broad technical, social, and economic forces that will influence water management and demand and supply of water in the twenty-first century. IWMI’s work will contribute to a broader global effort, preparing a “Vision for Water, Life and the Environment in the Twenty-first Century”, launched recently by the World Water Council. The world will have to go beyond the application of current thinking and creatively apply combinations of new technologies with principles like participation, devolution of authority, and pricing to cope with water scarcity equitably and effectively.
WATER SCARCITY IN THE TWENTY-FIRST CENTURY (pp. 29-42)
Abstract: As we approach the next century, more than a quarter of the world’s population or a third of the population in developing countries live in regions that will experience severe water scarcity. This paper reports on a study to project water supply and demand for 118 countries over the 1990-2025 period. The nature and geographic focus of growing water scarcity are identified. In the semi-arid regions of Asia and the Middle East, which include some of the major breadbaskets of the world, the groundwater table is falling at an alarming rate. There is an urgent need to focus the attention of both professionalsand policy makers on the problems of groundwaterdepletion, which must be seen as the major threat to food security in the coming century.
IRRIGATION MODELLING IN THE CONTEXT OF BASIN WATER RESOURCES (pp. 43-54)
Abstract: Management practices for irrigation schemes can often be improved by modelling the behaviour of a scheme and by evaluating its efficiency statistics. However, looking at an irrigation scheme without regard for other water uses within the river basin may not be effective. Efficiencies computed in this way are local and, since water may be used many times within the same basin, may not be realistic. Changes in water uses (e.g. irrigation, industrial, power production, urban water supply, navigation, environmental, recreational) will often have effects on other uses; and changes in irrigation schemes (management, structural, crop pattern) may affect other users within the basin. In addition, all water users will be affected by external changes such as changes in land cover or in climate. As demand for water increases, these links become more important until, at some stage, there is insufficient water for all users and hard choices must be made. Hydrological modelling is a tool that can be used to relate irrigation schemes to the other water uses within a river basin and can help in assessing real productivities and in evaluating alternative patterns of water usage. This paper discusses the techniques available to simulate irrigation schemes within overall basin water resources using, as an example, an intensively utilized basin in western Turkey.
WATER ACCOUNTING TO ASSESS USE AND PRODUCTIVITY OF WATER (pp. 55-71)
Abstract: A methodologyis demonstrated to account for the use and productivity of water resources. This water accounting methodology presents useful information to water resource stakeholders and decision makers to better understand the present use of water and to formulate actions for improvements in integrated water resources management systems. Based on a water balance approach, it classifies outflows from a water balance domain into various categories to provide information on the quantity of water depleted by various uses, and the amount available for further use. The methodology is applicable to different levels of analysis ranging from a micro level such as a household, to a macro level such as a complete water basin. Indicators are defined to give informationon the productivity of the water resource. Examples from Egypt’s Nile River and a cascade of tanks in Sri Lanka are presented to demonstrate the methodology.
WATER RESOURCES DEVELOPMENT PLANNING IN A BASIN CONTEXT IN THE ABSENCE OF GOOD HYDROLOGIC DATA: AN EXAMPLE FROM SRI LANKA (pp. 73-91)
Abstract: This paper describes a methodology for planning rehabilitation of smallscale irrigation systems in dry zones where the hydrologic database is poor. The methodology includes a two-stage decision-making process. The first stage relates to selection of cascades (meso-watersheds) within the basin for rehabilitation planning. The second stage is concerned with selection of tanks within a cascade and the type of rehabilitationcomponents to be planned, taking into considerationthe resource potential of the cascade and the socioeconomic factors of farmers. The methodology has been field-tested in Sri Lanka and shown to be efficient. A key principle underlying this approach is that development of any use of water within a basin must be viewed in the context of the whole basin to avoid conflicts over water use. Another principle is that hydrological and non-hydrological criteria must be used together to evaluate water resources development proposals.
CONTROL OF MALARIA MOSQUITO BREEDING THROUGH IRRIGATION WATER MANAGEMENT (pp. 93-105)
aInternational Water Management Institute (IWMI), Colombo, Sri Lanka; bDepartment of Zoology, University of Peradeniya, Peradeniya, Sri Lanka; cDepartment of Molecular Biology and Bio-Technology, University of Peradeniya, Peradeniya, Sri Lanka
Abstract: In the dry zone of Sri Lanka, an interdisciplinary study was conducted to evaluate the effects of irrigation water releases on malaria mosquito breeding and to identify different water management options for vector control. The relationship between abundance of larvae of the vector, Anopheles culicifacies (An. culicifacies), and the water level in a stream was described mathematically. An inverse function was derived and incorporated into a water balance model developed for the area. The larval abundance was quantified under different irrigation and water management scenarios. The result demonstrates potential for effective vector control by feasible changes in irrigation management.
DOMESTIC USE OF IRRIGATION WATER: HEALTH HAZARD OR OPPORTUNITY? (pp. 107-119)
aInternational Water Management Institute (IWMI), Colombo, Sri Lanka; bInternational Water Management Institute (IWMI), Lahore, Pakistan
Abstract: In an environment of growing scarcity and competition for water, there is increasing pressure on the irrigation sector to make irrigation for crop productionmore efficient and to transfer water to the urban, industrial and environmental sectors. However, irrigation water is extensively used for non-agricultural purposes, including domestic purposes, and an exclusive focus on water efficiency in agriculture could actually reduce the availability of domestic water within irrigated areas. It is argued, based on available literature, that this would have important health implications because in many developing countries the availability of water, rather than the quality of water, is of crucial importance to health. Two case studies are presented from Sri Lanka and Pakistan where people make use of irrigation water for a range of domestic activities. Water resource policies have to take these uses into account to avoid negative health implications for poor disadvantagedsegments of the population. Barriers to optimizing benefits of linking the irrigationwater supply to domestic needs seem to be institutional and psychological rather than medical, technical or economic.
TARGETING IRRIGATION SUPPORT TO POOR WOMEN AND MEN (pp. 121-140)
Abstract: Gendered poverty alleviation is an important aim of many governmental and non governmental irrigation agencies. This paper argues that the contribution of irrigation agencies to poverty alleviation is optimal if agencies target their support, and vest rights to newly developed irrigated land and water primarily in poor women and men. It is shown that the often-assumed trade-off between poverty alleviation and production growth probably does not exist. Further, agencies themselves play a preponderant role in including or excluding poor women and men in respect of rights in irrigated land and water. This role is especially strong in public irrigation, the focus of this paper. Evidence on the role of public irrigation agencies in allocating irrigated land and water rights is reviewed. Irrigated land is allocated through the site selection of infrastructural intervention, with or without changes in land tenure in the command area. Inclusion and exclusion occur implicitly through three principles of water rights allocation: on the basis of co-investments in infrastructure, on the basis of household composition, and on the basis of type of land rights.
MODELLING THE EFFECTS OF DEFICIT IRRIGATION ON SOIL SALINITY, DEPTH TO WATER TABLE AND TRANSPIRATION IN SEMI-ARID ZONES WITH MONSOONAL RAINS (pp. 141-159)
Abstract: A soil water and solute transport model, calibrated for a dominant soil series in the Punjab of Pakistan, was used to evaluate consequences of deficit irrigation in semi-arid areas with a shallow water table. Simulations were carried out to determine the influence of irrigation amounts and subsurface drainage conditions on root zone salinity, depth to water table and transpiration. Additional simulations were made to evaluate a range of irrigation practices adopted by farmers under field conditions. The simulation results show that provision of 80% of the cumulative evapotranspiration requirements as irrigation will result in acceptable limits of root zone salinity and depth to water table, without significantly affecting transpiration of wheat and cotton crops. Under such circumstances, subsurface drainagewill not be necessary. Results also show that current irrigation practices in the Punjab are resulting in yield reductions in general, due to either water shortage or waterlogging.
INDICATORS OF LAND AND WATER PRODUCTIVITY IN IRRIGATED AGRICULTURE (pp. 161-179)
Abstract: A set of four comparative performance indicators is defined, which relates outputs from irrigated agriculture to the major inputs of water and land. These indicators are presented with the objective of providing a means of comparing performance across and within irrigation systems. They require a limited amount of data that are generally available and readily analysed.Four typical applications of these indicators are illustrated: cross-system comparison; temporal variations in performance at one system; spatial variations within one system; and comparing performance by system type. Results of application of the indicators at 40 irrigation systems show large differences in performance among and within systems. In spite of uncertainties in estimation of indicators, the large differences discerned by the indicators justify the approach taken.
SATELLITE REMOTE SENSING FOR ESTIMATING PRODUCTIVITIES OF LAND AND WATER (pp. 181-196)
aInternational Water Management Institute (IWMI), Colombo, Sri Lanka, and International Institute for Aerospace Survey and Earth Sciences (ITC), Enschede, The Netherlands; bConsultant to IWMI (formerly with National Remote Sensing Agency, Hyderabad, India); cInternational Water Management Institute (IWMI), Colombo, Sri Lanka
Abstract: Satellite remote sensing offers the capability of objectively measuring spatiotemporalland surface parametersthat can provide information critical to irrigation performance studies. This study demonstrates the use of satellite remote sensing to identify the spatially distributed patterns of wheat yield and crop evapotranspiration for the Bhakra command area (1.2 million ha), in the Haryana State of north-west India. For the first time, satellite remote sensing has been used to obtain estimates of productivity per unit of water consumed by crop evapotranspiration,a key indicator of the performance of irrigated agriculture. It is shown that areas with the highest grain yield correspond to the areas having the highest evapotranspiration. Consequently, the spatial variations in crop production per unit evapotranspiration are less (cv 5 0.10) than spatial variations in productivity of land (cv 5 0.17). Whereas head- and tail end differences in three major branch canals were found for productivity of land, this trend was not detected for the productivity of water consumed. Causal factors for the spatial patterns of productivity need to be more thoroughly investigated. While calculation approaches are suggested to estimate productivity of land and water using satellite remote sensing, further research is required to refine these techniques. Better estimations of the productivity of land and water will allow for more detailed and objective performance studies at a range of scales from individual farm fields to entire irrigation schemes. It will help scientists understand productivity issues better, and enable water managers and policy makers to support improvements in the utilization of land and water resources.
IMPACT ASSESSMENT OF ORGANIZING FARMERS IN THE GAL OYA LEFT BANK IRRIGATION SCHEME, SRI LANKA (pp. 197-217)
Abstract: The nature and intensity of institutional interventions at the secondary unit level in the rehabilitationof the Gal Oya Left Bank irrigation system were different. The focus of this paper is to examine the impacts of these different interventions on the performance of secondary units using a time-series impact assessmentmodel. The impact assessment model appears to be able to describe with some precision the trends in the system as a whole, as well as distinguish between different impacts in different units. The results of the analysis demonstrate that areas that were intensively organized showed the greatest capacity to adopt improved management techniques quickly. However, these well-organized areas also happened to be more favoured before rehabilitation and have realized least satisfactory overall benefits. Tail-end areas, even though they were less intensively organized, showed the best overall performance in terms of water use, production and water productivity. But they took longer to respond fully to improved water delivery conditions.
AN ASSESSMENT OF THE IMPACT OF PARTICIPATORY IRRIGATION MANAGEMENT IN SRI LANKA (pp. 219-240)
Abstract: This paper presents the results of a study on the effects of participatory irrigation management in Sri Lanka. The study is based on the application of a methodology developed by the InternationalWater Management Institute (IWMI) to assess the impact of irrigation management transfer on the performance of irrigated agriculture. Performance is measured from several perspectives: financial, irrigation management, and agricultural productivity levels. Piecewise linear regression models are fitted to compare trends in performance during the five-year period before transfer and five years after. The results show that there has been a significant drop in government’s recurrent expenditure for irrigation over time. The decline is not confined to schemes where participatorymanagement had been introduced but to other schemes as well. The cost of irrigation to farmers has remained the same before and after transfer. The analysis reveals that irrigation management transfer alone did not bring about significant improvements in the quality of irrigation or agricultural productivity levels. However, in schemes where both management transfer and physical rehabilitation had occurred, significant improvements in agricultural productivity were noted.
The Politics of Water: Urban Protest, Gender and Power in Monterrey, Mexico, Vivienne Bennett, Pittsburgh, University of Pittsburgh Press, 1995
Roundtable Consultation on Irrigation, Rabat, Morocco, 26-28 October 1998
Workshop on Water Resources Management in the Islamic World, Amman, Jordan, 1-3 December 1998