Search Results

Now showing 1 - 10 of 20
  • Conference Paper
    Comprehensive Options Assessment: The Pongolo
    (2003) McCartney, Matthew; Janganyi, Joan; Mkhize, Sizwe
    "The Pongolopoort dam, which impounds the water of the Ponogolo River in KwaZulu Natal, South Africa, was built in the 1970s to provide water for irrigation. The dam is located where the river flows through a narrow gorge between the Lebombo and Ubombo mountain ranges, close to the border with Swaziland. Immediately downstream of the dam, a broad alluvial plain, known as the Pongolo Floodplain, extends from the dam to the confluence of the Pongolo and Usutu Rivers, close to the border with Mozambique. Within Mozambique, the river is known as the Rio del Maputo. The river gradient through the Pongolo Floodplain, which is approximately 130 km2 in extent, is just 0.033 m km-1. The floodplain is one of the most biologically diverse ecosystems in South Africa. It comprises the meandering river and a highly heterogeneous complex of lagoons, ox-bow lakes, abandoned river channels, marshes, levees and floodplain grassland, which provide habitat for a wide range of birds and animals."
  • Working Paper
    Wetlands, Agriculture and Poverty Reduction
    (2010) McCartney, Matthew; Rebelo, Lisa-Marie; Sellamuttu, Sonali Senaratna; de Silva, Sanjiv
    "Wetlands contribute in diverse ways to the livelihoods of millions of people. They are often inextricably linked to agricultural production systems. In many places, growing population, in conjunction with efforts to increase food security, is escalating pressure to expand agriculture within wetlands. The environmental impact of wetland agriculture can have profound social and economic repercussions for people dependent on ecosystem services other than those provided directly by agriculture. If wetlands are not used sustainably, the functions which support agriculture, as well as other food security and ecosystem services, including water-related services, are undermined. Currently, the basis for making decisions on the extent to which, and how, wetlands can be sustainably used for agriculture is weak. There is a dearth of knowledge on the best agricultural practices to be applied within different types of wetlands and a lack of understanding on how to establish appropriate management arrangements that will adequately safeguard important ecosystem services. Often, wetland policies are underpinned by a conservationist perspective that regards agriculture simply as a threat and disregards its important contribution to livelihoods. This report synthesizes findings from multidisciplinary studies conducted into sustainable wetland agriculture by IWMI and partners in Africa and Asia. It highlights the value of wetland agriculture for poverty reduction as well as the need for more systematic planning that takes into account trade-offs in the multiple services that wetlands provide."
  • Working Paper
    Agricultural Water Storage in an Era of Climate Change: Assessing Need and Effectiveness in Africa
    (2013) Rebelo, Lisa-Maria; McCartney, Matthew; Xenarios, Stefanos; Smakhtin, Vladimir
    "By mitigating the vagaries of climate variability, agricultural water storage is widely anticipated to make a key contribution to climate change adaptation in Africa. However, if the planning of water storage is not improved, it is likely that many investments will fail to fully deliver intended benefits. This report describes the agricultural water storage continuum and some of the possible implications of climate change. A simple diagnostic tool which can be used to provide a rapid evaluation of the need and effectiveness of different water storage options, under existing and possible future climate conditions, is presented."
  • Working Paper
    Evaluating the Flow Regulating Functions of Natural Ecosystems in the Zambezi River Basin
    (2013) McCartney, Matthew; Cai, Xueliang; Smakhtin, Vladimir
    "This report summarizes the findings of a literature review conducted to find evidence of the flow regulating functions of the major ecosystems in the Zambezi River Basin. It also describes a pragmatic approach for quantifying the flow regulating functions of floodplains, headwater wetlands and miombo forests in the basin. The method utilizes observed streamflow records and flow duration curves to derive a simulated time series of flow in the absence of the ecosystem. This can then be compared with an observed time series to evaluate the impact of the ecosystem on the flow regime. The method has been applied to 14 locations in the basin. Results indicate that the different ecosystems affect flows in different ways. Broadly: i) floodplains decrease flood flows and increase low flows; ii) headwater wetlands increase flood flows and decrease low flows; iii) miombo forest, when covering more than 70% of the catchment, decreases flood flows and decreases low flows. However, in all cases there are examples which produce contrary results and simple correlations between the extent of an ecosystem type within a catchment and the impact on the flow regime were not found."
  • Working Paper
    Working Wetlands: Classifying Wetland Potential for Agriculture
    (2005) McCartney, Matthew; Masiyandima, Mutsa; Houghton-Carr, Helen A.
    "In many developing countries, improvement in natural resource management is widely perceived to be the key to sustainability, and central to overcoming both developmental and environmental problems. The trade-off between environmental protection and development is most acute in fragile ecosystems such as wetlands. Wetlands are of value because they play an important role in maintaining environmental quality, sustaining livelihoods and supporting biodiversity. Many wetland functions effectively 'work' for the benefit of people. However, social and economic factors often result in pressure to make wetlands work harder, for example, through their utilization for agriculture. Astute development and management of wetlands can add considerable value to the 'goods' and 'services' that they provide, but care is needed because inappropriate use undermines long-term benefits. "In this report, a 'working wetland' is defined as a managed wetland in which a rational compromise is made between its ecological condition and the level of human utilization. A systematic and semi-quantitative method of evaluation is presented, which enables the classification of the 'potential' of using a working wetland for specified agricultural activities. The approach, which is underpinned by the concept of 'wise use,' is based on a form of multi-criteria analysis that integrates biophysical and socioeconomic aspects of wetland utilization. The 'potential class' emerges from the aggregation of two values. The first of these arises from an appraisal of both the biophysical and socioeconomic suitability of using the wetland for agriculture. The second results from an assessment of the possible hazards, in relation to both social welfare and the ecological condition of the wetland. The method, which is demonstrated by application to three case studies, is a pragmatic approach that provides a context for making explicit the trade-offs associated with wetland agriculture. It enables a preliminary screening of proposed activities prior to more detailed environmental and health impact assessments."
  • Working Paper
    The Water Resource Implications of Changing Climate in the Volta River Basin
    (2012) McCartney, Matthew; Forkuor, Gerald; Sood, Aditya; Amisigo, Barnabas; Hattermann, Fred; Muthuwatta, Lal
    "The International Water Management Institute (IWMI) has published a paper examining the potential impacts of climate change on food and energy production in the Volta River Basin. The Volta River supplies the water needs of more than 24 million people in Benin, Burkina Faso, Côte d’Ivoire, Ghana, Mali and Togo. It also hosts a number of major water management and hydropower development projects, such as the Akosombo Dam in Ghana and Lake Volta, the world’s fourth largest reservoir by volume. The IWMI report uses climate and hydrological modelling to identify and quantify the potential threat that climate change poses to existing and planned development projects."
  • Working Paper
    Agricultural Water Management in a Water Stressed Catchment: Lessons from the RIPARWIN Project
    (2007) McCartney, Matthew; Lankford, Bruce; Mahoo, Henry F.
    "In the face of growing water stress and increasing concerns over the sustainability of water use, Tanzania has, in common with many other countries in Africa, focused largely on the development of more integrated catchment-wide approaches to water management. In the Great Ruaha River Basin, considerable effort has gone into increasing water productivity and the promotion of mechanisms for more efficient allocation of water resources. Over a period of five years, the RIPARWIN project investigated water management in the basin and evaluated the effectiveness of some of the mechanisms that have been introduced. The study findings are relevant to basins in developing countries where there is competition for water and irrigation is one of the main uses."
  • Working Paper
    Decision Support Systems for Large Dam Planning and Operation in Africa
    (2007) McCartney, Matthew
    "Dam planners and operators often have to consider a huge number of factors and conflicting objectives. This makes decision making extremely difficult. In such situations, decision support systems (DSS) have an important role to play. Over the years, many different DSSs have been developed for dam planning and operation. This report presents a review of the different types of DSS and their application in water resource management. Although some information and examples have been obtained from elsewhere, the main focus is Africa. The report is not a comprehensive compendium on DSS application in dam planning and operation, but rather, it provides an overview and framework for understanding issues pertaining to decision-making in relation to large dams in Africa."
  • Working Paper
    Minimizing the Negative Environmental and Health Impacts of Agricultural Water Resources Development in Sub-Saharan Africa
    (2007) McCartney, Matthew; Boelee, Eline; Cofie, Olufunke O.; Mutero, Clifford M.
    "This paper provides a synopsis of environmental and health impacts arising from agricultural water development in sub-Saharan Africa and recommends ways to increase the sustainability of investments in irrigation by giving greater prominence to health and environmental concerns. The paper presents a conceptual framework for considering environmental and health issues in tandem; reviews current environmental and health assessment tools; describes national and donor policies; and analyzes current constraints to successful environmental and health planning and management. On the basis of findings, it makes recommendations to improve planning and management across a range of scales. The recommendations are of relevance to both water and agricultural planners and are timely, in the light of recent calls for significant increases in irrigation investment as a contribution to achieving the Millennium Development Goals."
  • Working Paper
    Evaluation of Current and Future Water Resources Development in the Lake Tana Basin, Ethiopia
    (2010) McCartney, Matthew; Alemayehu, Tadesse; Shiferaw, Abeyu; Awulachew, Seleshi Bekele
    "Lake Tana is valuable for many people, including the communities who live around the lakeshore, those living on islands and close to the Blue Nile River, which flows from it. The area has been identified as a region for irrigation and hydropower development, which are vital for food security and economic growth in Ethiopia. This report presents findings from an integrated multidisciplinary study that was conducted to investigate the implications of this development. The study found that existing water resources development, for hydropower generation, has modified flows downstream of the lake, reduced water levels of the lake and significantly decreased flow over the Tis Issat Waterfall. Interviews with stakeholders indicate that the changes have benefited some people but have adversely affected others. Future development will exacerbate pressure on the lake."