Like many rapidly developing countries, Vietnam is seeking to find a balance between socio-economic development along river systems and the protection of ecosystems that river flows support. An innovative AWP-funded environmental flows framework and assessment approach is helping Vietnam to achieve this balance.
Vietnam has 106 river basins, including 10 major river basins with catchments larger than 10,000km2. As sites of ‘clean energy’ (hydropower) production and the sources of fresh water for consumption and irrigation, rivers support the daily lives and livelihoods of millions of Vietnamese people. Both hydropower and irrigation require the storage of water in dams, which dramatically alter the variability and seasonality of downstream river flows and negatively impact downstream aquatic environments.
Vietnam’s Department of Water Resource Management (DWRM) appreciates the importance of a healthy river system for supporting aquatic plants and animals, and for sustaining the ‘ecosystem services’ and socio-economic benefits that river environments provide to Vietnam’s population, such as freshwater quality and quantity and fisheries. Vietnam’s Water Law requires the delivery of minimum flows to support the “normal development of aquatic ecosystems”. The existing approach provides only limited environmental protection. The Water Law is currently being revised, giving the Government of Vietnam an opportunity to improve their approach to minimum flows and better protect river environments.
Environmental flows describe the quantity, timing, and quality of freshwater flows and levels necessary to sustain aquatic ecosystems which, in turn, support human cultures, economies, sustainable livelihoods, and well-being. An environmental flow regime typically consists of several flow components (baseflows, pulses, bankfull flows etc.) each of which performs important ecological functions. For example, pulses cue fish migration and breeding while bankfull flows move sediment and maintain channel shape. ‘Holistic’ approaches to the determination of environmental flow regimes are widely regarded as industry best practice, but they require substantial funding and ecological expertise and are currently not feasible in Vietnam.
Funded by the Australian Water Partnership and working closely with DWRM and the Center for Water Resource Information -Economics, Alluvium developed and piloted an innovative environmental flows framework and approach to assessing minimum flows. The approach fundamentally changes the definition of minimum flows away from the existing single low flow rate to a multi-component flow regime that captures the variability and seasonality of normal ‘pre-development’ river flows. Hydrological and statistical methods are used to determine the size, duration and frequency of each flow component. Importantly, the approach draws on Australian and international best practices whilst being appropriate for the Vietnam context. The approach can be applied by DWRM in any river basin for which normal (modelled or gauged) flow data is available.
If adopted, the approach offers substantially better protection of aquatic ecosystems – as well as benefits to communities who rely on a healthy river system – and will allow time for holistic environmental flows approaches to be taken into consideration, if required. The approach was piloted in the Vu Gia – Thu Bon system in central Vietnam, which has complex hydropower operations and water resource challenges.
The project involved three visits to Vietnam by the Alluvium team to meet with in-country partners, key Government personnel, visit pilot basin sites, and to provide training sessions to build the capacity of stakeholders to understand and implement the approach. DWRM will now use the outputs of the project – a framework for environmental flows and roadmap – to refine their approach to minimum flows and publish minimum flows for all major basins in the country.
This work will have an enduring, positive impact on the management of water resources and the health of rivers and communities in Vietnam.