KSA: Water Resources and Ecosystems
Title: SP3 – Sustainable Dredging of Dams
ToR ID: 1009816
Contact Person: Dr Eunice Ubomba-Jaswa euniceuj@wrc.org.za
Wandile Nomquphu wandilen@wrc.org.za
Closing Date: 16 August 2020
Brief description of ToR
The main objective of this project will be to develop a sustainable dam dredging model and protocols for a variety of “learning” dams and contexts. Dams and reservoirs inevitably face the problem of sedimentation accumulation over time which leads to the loss of capacity to store water and the potential effects on the structural integrity. Dam sedimentation leads to clogging, disruption of the sediment balance, and the increasing accumulation of polluted sediments. Historically, sediment management strategies have included constructing sediment traps, raising the dam or building of a new dam BUT this does not solve the sedimentation accumulation in the dam. Therefore, an alternative strategy is to remove the sediment from the dam by dredging. Dredging will lead to the increase in the water storage volume, enhance the water quality and remove contaminated material. However, dredging of dams is a costly exercise and must be well considered. Prevention of sediment inflows will be key to the implementation of any successful dam rehabilitation plan. However, in many cases we do not have the option of developing new dam infrastructure. Dredged sediment quality might be compromised due to sediment contamination with hazardous concentrations of substances both chemical and biological in nature. Considerations as to when to dredge, how to dredge and with what dredging equipment, and what to use the dredged sediment for need to be based on an efficient sediment quality monitoring system, hazardous waste methodology as well as a health risk assessment protocols derived for the intended use of the sediment (on land use or return to the surface water body).
