Impounding Reservoirs, Benefits and Risks: A Review of Environmental and Technical Aspects of Construction and Operation

The operation of multi-functional reservoirs, together with their benefits and risks, is a complex issue. The scientific and social discussion has been burgeoning recently, and all the more so as no planning and technological solutions for the realisation of storage reservoirs have yet been worked out that could represent a universal approach, assuming ecologically and socially sustainable operations, maximising economic returns and supporting the development of the region concerned. Although the creation of each reservoir facility involves different engineering and environmental considerations, this article attempts to isolate the key benefits of impounding reservoirs and to summarise the risks associated with their operation, considering flood protection, retention, environmental and social aspects and water quality. Based on a review of the scientific literature for each of these aspects, various sub-categories representing intensively developing sectors of research were distinguished, and the published results were used to formulate a register taking into account the spectrum of impact of a given factor and a proposal for remedial action. As a basic conclusion of this review, it can be pointed out that the current development of scientific research, technological progress in hydrotechnical engineering and information technology, as well as advanced data analysis capabilities, provide the basis for developing sustainable solutions to avoid or mitigate the negative impact of all the identified risks. In addition, remedial measures in the catchment area and the reservoir should be taken on board to counteract the negative effects of reservoirs. The results presented can be a valuable source of information for institutions responsible for the planning and implementation of investments in the construction of multi-functional reservoirs.