Decision support systems for environmental flows: Lessons from Southern Africa

The decision by a number of countries to re-engage with large dams creates an obligation to ensure that the attendant environmental and social consequences are dealt with adequately. In this regard, the key challenges for the future are the assessment and management of downstream environmental and social impacts. The paper examines these issues in the context of southern Africa, particularly the Lesotho Highlands Water Project. It examines the ways in which Environmental Flows can affect the environment and the livelihoods of riparians, the need to make trade-offs between different uses of the water, and the difficulties of making trade-offs if the values of stakeholders regarding water use are not supported by a legal framework. The paper highlights the need to undertake environmental flow work early in the project cycle as part of the Environmental Impact Assessment, and the need to integrate environmental flow factors into the project's economic analysis. It explores the financial trade-offs that are implicit in environmental flow work, the need for a multi-disciplinary team to carry out the work, and the need for a transparent decision framework. Finally, the importance of establishing a decision support system for use during the operational phases of the project is highlighted.