For integrated water resources management both blue and green water resources in a river basin and their spatial and temporal distribution have to be considered. This is because green and blue water uses are interdependent. In sub-Saharan Africa, the upper landscapes are often dominated by rainfed and supplementary irrigated agriculture that rely on green water resources. Downstream, most blue water uses are confined to the river channels, mainly for hydropower and the environment. Over time and due to population growth and increased demands for food and energy, water use of both green and blue water has increased. This book provides a quantitative assessment of green-blue water use and their interactions. The book makes a novel contribution by developing a hydrological model that can quantify not only green but also blue water use by many smallholder farmers scattered throughout the landscape. The book provides an innovative framework for mapping ecological productivity where gross returns from water consumed in agricultural and natural vegetation are quantified. The book provides a multi-objective optimization analysis involving green and blue water users, including the environment. The book also assesses the uncertainty levels of using remote sensing data in water resource management at river basin scale.

This study aims at improving the hydrological process understanding of the semi-arid and transboundary Incomati river basin to enable better water management. Comprehensive statistical and trend analysis of rainfall and streamflow were conducted, and the Indicators of Hydrological Alteration tool was deployed to describe the streamflow regime and trends over time. Land use and land cover change, particularly the conversion of natural vegetation into forest plantation, the expansion of irrigated agriculture and the flow regulation due to dam operation were identified as critical drivers of flow regime alteration. Hydrograph separation using long-term hydrochemical data at seasonal scale, and hydrochemical and isotope data at event scale were performed to quantify runoff components. A novel methodology to calibrate recursive digital filters using routinely collected water quality data was developed and tested in the catchment. This method allows for estimation of daily baseflow from readily available daily streamflow data. Dominant runoff generation zones were mapped using the Height Above Nearest Drainage approach. The hydrological model STREAM was then employed, informed by the runoff generation zones mapping and the process understanding gained in the catchment, as well as remote sensing data. The study provides the basis for better operational water management in the catchment.

There are four papers focusing on the special recent experience of South Africa, as it replaces former inequitable water laws with a new one tq reflect its major pOlitical reorientation, and at the same time takes this opportunity of change to bring in several other principles of modern thinking about water, with a focus on participation by stakeholders, on the river-basin as management unit, on financial principles such as "users pay" and "polluters pay;' and on the potential role of access to water in addressing social issues such as poverty and gender discrimination. Conflict / Social aspects / Gender / Water law / Institutional constraints / Financing / Investment / Water scarcity / Water users' associations / Privatization / User charges / Water allocation / Political aspects / Water use efficiency / Water policy / Developing countries / Agricultural development / Poverty / Watercourses / River basins / Water management

This interdisciplinary volume examines how nine arid or semi-arid river basins with thriving irrigated agriculture are doing now and how they may change between now and mid-century. The rivers studied are the Colorado, Euphrates-Tigris, Jucar, Limarí, Murray-Darling, Nile, Rio Grande, São Francisco, and Yellow. Engineered dams and distribution networks brought large benefits to farmers and cities, but now the water systems face multiple challenges, above all climate change, reservoir siltation, and decreased water flows. Unchecked, they will see reduced food production and endanger the economic livelihood of basin populations. The authors suggest how to respond to these challenges without loss of food production, drinking water, or environmental health. The analysis of the political, hydrological, and environmental conditions within each basin gives policymakers, engineers, and researchers interested in the water/sustainability nexus a better understanding of engineered rivers in arid lands.

Decentralization and increased stakeholder involvement have been major elements of water sector reform as ways to promote sustainable and integrated resource management particularly of river basins. Based on an analytical framework for relating decentralization and stakeholder involvement to improved river basin management, this paper infers several hypotheses about factors associated with greater or lesser likelihood of success of the decentralization process using data from 83 river basins worldwide. The results suggest that physical, political, economic, financial, and institutional characteristics of the basin do affect the process and the level of performance of the decentralization. In particular, the presence of water scarcity may be a stimulus to reform, uniting the stakeholders in the basin and leading to better performance; organized user groups push for the initiation of decentralization reforms but may be associated with costs to the process and difficulty of achieving decentralization; the existence of dispute resolution mechanisms supports stakeholder involvement and improves decentralization performance; where stakeholders accepted greater financial responsibility, complying with tariffs and contributing to the budget for basin management, the decentralization process and performance measures increased; basins with higher percentages of their budgets from external governmental sources benefited from better stability and support and it shows in the performance of the decentralization process.

"The authors describe and analyze river basin management in the Guadalquivir River Basin in Spain. The Guadalquivir river flows westerly across southern Spain, with nearly all of its 57,017 km2 drainage area within the region of Andalusia. Water management issues in this semi-arid, heavily agricultural, but rapidly urbanizing region include drought exposure, water allocation, water quality, and in some areas, groundwater overdraft. A river basin agency (Confederacion Hidrografica del Guadalquivir, or CH Guadalquivir) has existed within the basin since 1927, but its responsibilities have changed substantially over its history. For much of its life, CH Guadalquivir's mission was water supply augmentation through construction and operation of reservoirs, primarily to support irrigation, under central government direction with little provision for water user participation. Following the Spanish political system's transformation and Spain's accession to the European Union, water law and policy changes greatly expanded CH Guadalquivir's responsibilities and restructured it to incorporate representation of some basin stakeholders. Although the basin agency's accomplishments in reservoir construction have been prodigious, its record of performance with respect to its newer responsibilities has been mixed, as have perceptions of its openness and responsiveness to basin interests other than irrigators. This paper--a product of the Agriculture and Rural Development Department--is part of a larger effort in the department to approach water policy issues in an integrated way. The study was funded by the Bank's Research Support Budget under the research project "Integrated River Basin Management and the Principle of Managing Water Resources at the Lowest Appropriate Level: When and Why Does It (Not) Work in Practice?""--World Bank web site.

Africa's high dependence upon natural resources makes the continent particularly vulnerable to changes in the availability of water as a result of climate changes. In this study, the vulnerability of water resources to environmental change is assessed on a river/lake/groundwater basin scale for the Southern, Eastern, Western and Northern African regions.