Sustainable use of river ecosystems requires that they be managed holistically. This paper describes an holistic methodology, DRIFT (Downstream Response to Imposed Flow Transformation), for advising on environmental flows for rivers targetted for water-management activities. DRIFT's basic philosophy is that all major abiotic and biotic components constitute the ecosystem to be managed; and within that, the full spectrum of flows, and their temporal and spatial variability, constitute the flows to be managed. The methodology employs experienced scientists from the following biophysical disciplines: hydrology, hydraulics, fluvial geomorphology, sedimentology, chemistry, botany and zoology. Where there are subsistence users of the river, the following socio-economic disciplines are also employed: sociology, anthropology, water supply, public health, livestock health and resource economics.DRIFT is a structured process for combining data and knowledge from all the disciplines to produce flow-related scenarios for water managers to consider. It consists of four modules. In the first, or biophysical module, the river ecosystem is described and predictive capacity developed on how it would change with flow changes. In the second, or socio-economic module, links are described between riparian people who are subsistence users of river resources, the resources they use, and their health. The objective is to develop predictive capacity of how river changes would impact their lives. In the third module, scenarios are built of potential future flows and the impacts of these on the river and the riparian people. The fourth, or economic module, lists compensation and mitigation costs.DRIFT should run in parallel with two other exercises which are external to it: a macro-economic assessment of the wider implications of each scenario, and a Public Participation Process whereby people other than subsistence users can indicate the level of acceptability of each scenario.DRIFT has been developed in a semi-arid, developing region, where water-supply problems are pressing, and uncertainties about river-linked ecological and social processes high. The use of DRIFT in this context is discussed.

Iso-Ahola’s theory asserts that personal escape, personal seeking, interpersonal escape, and interpersonal seeking motivate tourism and recreation. This article operationalizes and empirically tests Iso-Ahola’s theory for similar tourism and recreation experiences. The motivation dimensions are monitored using scenario-based data for sporting events, beaches, amusement parks, and natural parks. The first investigation used confirmatory factor analysis to explore the efficacy of six competing motivational structures. Three of these competing models achieved superior and similar fit statistics, with one model incorporating the most parsimonious structure. This model gave equal and direct salience to each of the four motivations. The second investigation examined the differences in motivation levels for tourism and recreation experiences. Tourism experiences exhibited higher levels of motivation, particularly for the personal seeking and personal escape dimensions. The third investigation found no relationship between the number of recent domestic and international vacations and tourism motivations among the subjects.

The term "environmental flows" is now widely used to reflect the hydrological regime required to sustain freshwater and estuarine ecosystems, and the human livelihoods and well-being that depend on them. The definition suggests a central role for ecohydrological science to help determine a required flow regime for a target ecosystem condition. Indeed, many countries have established laws and policies to implement environmental flows with the expectation that science can deliver the answers. This article provides an overview of recent developments and applications of environmental flows on six continents to explore the changing role of ecohydrological sciences, recognizing its limitations and the emerging needs of society, water resource managers and policy makers. Science has responded with new methods to link hydrology to ecosystem status, but these have also raised fundamental questions that go beyond ecohydrology, such as who decides on the target condition of the ecosystem? Some environmental flow methods are based on the natural flow paradigm, which assumes the desired regime is the natural "unmodified" condition. However, this may be unrealistic where flow regimes have been altered for many centuries and are likely to change with future climate change. Ecosystems are dynamic, so the adoption of environmental flows needs to have a similar dynamic basis. Furthermore, methodological developments have been made in two directions: first, broad-scale hydrological analysis of flow regimes (assuming ecological relevance of hydrograph components) and, second, analysis of ecological impacts of more than one stressor (e.g. flow, morphology, water quality). All methods retain a degree of uncertainty, which translates into risks, and raises questions regarding trust between scientists and the public. Communication between scientists, social scientists, practitioners, policy makers and the public is thus becoming as important as the quality of the science. lois et des politiques de mise en oeuvre de débits environnementaux en espérant que la science peut fournir les réponses. Ce document donne un aperçu des développements et des applications récents de débits environnementaux sur les six continents dans le but d'explorer l'évolution du rôle des sciences éco-hydrologiques, en reconnaissant leurs limites et les nouveaux besoins de la société, des gestionnaires des ressources en eau et des décideurs politiques. La science a répondu par de nouvelles méthodes pour relier l'hydrologie à l'état des écosystèmes, mais à cette occasion des questions fondamentales ont été soulevées qui vont au-delà de l'éco-hydrologie, telles que : qui décide de l'état souhaité pour un écosystème ? Certaines méthodes de débits environnementaux sont basées sur le paradigme de l'écoulement naturel, ce qui suppose que le régime souhaité est la condition naturelle « non modifiée ». Cela peut être irréaliste là où les régimes d'écoulement ont été modifiés pendant de nombreux siècles et sont susceptibles d'évoluer avec le changement climatique ...

The demand for water from South Africa’s growing population is creating an ever-increasing pressure on the country’s rivers. The urgent need to provide more water services often conflicts with the desire to maintain or improve the ecological condition of the rivers. To provide guidance on the sustainable use of a river’s water-resources, the Building Block Methodology (BBM) has been developed for assessing the instream flow requirement for any river. Development has been done jointly over the last five years by the national Department of Water Affairs and Forestry (DWAF) and river scientists, and the accent is on identifying a complex of different magnitude flows for maintenance of entire river ecosystems. The BBM caters for the almost universal reality in South Africa of having rapidly to provide scientific guidance on such flows for a river in cases where biological data and understanding of the functioning of the river are limited. However, the methodology works equally well in data-rich situations. The BBM depends on available knowledge and expert opinion, gleaned from experienced river scientists in a structured workshop process. Limited new data of a specific nature are gathered to facilitate the process. Relevant data on the river are prepared in a way that workshop participants can easily understand and quickly begin to use. Scientists typically involved in the workshop, all with specific roles, are those with specialist knowledge of the river or similar rivers in terms of the fish, aquatic invertebrates, riparian vegetation, river importance, habitat integrity, fluvial geomorphology, local hydraulics, water chemistry and social dependence on the riverine ecosystem. Hydrological and hydraulic modelers provide data inputs and facilitate the workshop process by answering questions and producing additional data as requested. The workshop output, reached by consensus, is a quantitative description in space and time of a flow regime that should facilitate maintenance of the river ecosystem in some pre-determined desired future state. Information from a BBM workshop is used by DWAF in the Planning phase of a proposed water-resource development. Further development of the BBM, to extend it into the Design, Construction and Operation phases, has been initiated. This includes linking with a public participation process, input into design of the scheme, base-line studies of the river and subsequent monitoring to assess the efficacy of the recommended flow regime.

1. This study summarises our development and application in developing countries of a process for assessing the ecological, social and economic costs and benefits of waterresource developments, as an aid to basin planning. 2. During 15 years of work in Africa and Asia, the process sequentially included the whole river ecosystem and the whole flow regime in the assessment; used a multidisciplinary team and a scenario-based approach that gave equal weighting to the ecological, social, resource-economic and macro-economic costs and benefits of development; quantified or semi-quantified the costs and benefits in data-poor situations, capturing expert opinion and local wisdom as well as data; recognised that the final allocation of water for ecosystem maintenance should be a societal choice of trade-offs between resource protection and development. 3. Flow assessments were increasingly done at the basin rather than project level and introduced the concept and practicality of Development Space as a tool to aid basin planning. 4. Later assessments included valuation of regulating, cultural and provisioning services provided by rivers as part of the cost-benefit analysis. 5. Implementation of managed flows as outlined above is a complex and long-term process that should include a number of major steps, from development of the appropriate legislation to monitoring of management decisions and adaptive management. Country or region-wide implementation at this scale could well take one to two decades, even where the political will and technical skills exist. 6. We conclude by offering eight principles that we believe would promote genuinely sustainable use of rivers.