Dealing with Minimum Flows

Determination of environmental flows, the release of these flows and the monitoring and reporting to Ugandan lead agencies remain an unresolved issue where additional efforts are required by the GoU and project developers. GET FiT has identified key gaps and opportunities to close these.

The release of a minimum flow1 is a standard mitigation measure for hydropower projects to reduce impacts on people and ecosystems along the affected river section between the intake and the point where water is returned to the river, a river section often several kilometres long.

The volume of the minimum flow also directly impacts on the economic viability of a hydropower project (see GET FiT Annual Report 2017, pp. 49-50, for more information). Lessons on this important topic continued to be generated under GET FiT in 2018.

During the initial stages of GET FiT, the lack of clear expectations from Ugandan lead agencies on the requirements and frameworks expected to be followed when deriving minimum flows proved challenging to most project developers. Guidance on determining minimum flows is important to ensure predictability and transparency in the determination of minimum flow requirements. Therefore, programmes such as GET FiT may benefit substantially from modest early investments in improving clarity on environmental flow expectations together with relevant in-country authorities.

During detailed design and construction, a variety of solutions to release and monitor the minimum flows were proposed by project developers. Most of the proposed solutions were deemed not fit for purpose by GET FiT and multiple iterations were typically required to arrive at viable designs. Future programmes will likely benefit from clarifying minimum requirements for environmental flow release arrangements at an early stage and in collaboration with relevant lead agencies.

With an increasing number of GET FiT supported projects entering the operation phase, further lessons were identified in 2018. Release of minimum flow volumes below the requirements set by Ugandan authorities and GET FiT were uncovered along with missing or incorrect reporting to the relevant agencies. This underlines the importance of identifying appropriate monitoring mechanisms for the minimum flow releases and ensuring data is captured and available for independent verification.

Future programmes like GET FiT could develop minimum requirements for monitoring and reporting in cooperation with relevant agencies, including the off taker of electricity generated, that may have requirements for calculating deemed energy which may affect the minimum flow monitoring arrangements.


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1 We refer to ‘minimum flow’ rather than the often-used concept of ‘environmental flow’ as the minimum flow requirements defined in Uganda (by the Directorate of Water Resources Management) usually do not have the characteristics of a true environmental flow, namely a descriptionof the quantity, timing and quality of water flows required to sustain freshwater ecosystems and human livelihoods that depend on these ecosystems