2022 – Realities of Risk for small dams, barrages and weirs in run-of-river hydropower in developing nations: One approach does not fit all

Andrew Noble – WSP Australia

The resurgence of privately owned, small run-of-river hydropower projects leads to rapid learning curves for some first-time project developers. This paper explores the wider theme of the perception of risk versus reality of risk, and the challenges and opportunities for the scheme’s developer and designer, in striking a risk balance when adopting engineering solutions that are appropriate for the local construction practices. The headworks for such schemes usually comprise a low height diversion weir, or barrage with side intake. These are not complex structures but the designer needs to work with what resources are readily available in country and often has to revert to grass roots engineering to incorporate practical constructability into the design, while giving special attention to the future limitations for machinery to assist with operation and maintenance aspects. More labour-intensive methods for trimming of excavations and for placing of concrete are not uncommon.

The stakeholders in small hydropower schemes are many: the community, the approval agencies, the lenders, the developers, the local construction industry, and the relevant governmental approval authority. Design decisions cannot be made in a vacuum and design decisions need to consider the social, political, environmental and commercial context of their project.

Engineering design produced in industrialised nations is encumbered with design methods, standards and construction process familiarities that can result in inappropriate design solutions for developing nations, especially in hard to reach remote locations. This is no more apparent than with the design of small hydropower projects where the small schemes need to benefit commercially from being fast-tracked to development, although budgets are small and the implications of poor decisions can easily threaten the viability of schemes.