Assessing Environmental Flow Requirements and Trade-offs:
For the Lower Zambezi River and Delta, Mozambique
The Zambezi Delta is vital to Mozambique’s national economy and is a Wetland of International Importance. Large dams in the Zambezi catchment have substantially altered the magnitude, timing, duration, and frequency of flooding events in the delta, resulting in adverse ecological and socio-economic changes. We evaluated conflicts/trade-offs among various water uses and the potential for improving delta conditions through environmental flow releases from Cahora Bassa Dam, using the downstream response to imposed flow transformations (Brown, C.A. and Joubert, A., 2003. Using multicriteria analysis to develop environmental flow scenarios for rivers targeted for water resource development.
Water SA, 29 (4), 365–374; King, J.M., Brown, C.A., and Sabet, H., 2003. A scenario-based holistic approach to environmental flow assessments for regulated rivers. Rivers Research and Applications, 19 (5–6), 619–640) model. Five variations in low flows, 18 alternatives for annual floods, and one extreme (1:5 year) flood were considered for a range of uses/concerns, including commercial and small-scale agriculture, estuarine ecology, coastal and freshwater fisheries,livestock, large mammals, waterbirds, vegetation, invasive species, natural resources, water quality, navigation, and groundwater recharge.
The study revealed minimal trade-offs among different uses with regard to reinstating environmental flows.