Use of decision support systems to improve dam planning and dam ...

DSSs can make important contributions to many aspects of estimating downstream environmental flows.
For the simpler approaches the best are those, such as the DRM, that compute both high and low flow
requirements based on naturalized flow series. The more complex approaches will often utilize a range of
DSSs to investigate intricate ecological processes and requirements (e.g., habitat requirements for specific
fish species) as well as the social and economic implications of different possible flow regimes.
The broad impacts of modification of the flow regime are now well understood. However, all dams are
unique and often there is often great uncertainty of specific impacts and, in particular, the likely socioeconomic
implications of change. DSSs are being increasingly combined with expert judgment to gain insights into
flow-ecosystem links and in turn the links to livelihoods (see Appendix 1, Application of DRIFT).
Environmental flows are essential for the sustainable and equitable development of aquatic resources. The
countries of sub-Saharan Africa would benefit significantly from programs to build capacity in environmental
flow assessment. As a starting point, these should be developed using the expert opinion of national ecologists,
hydrologists, social scientists and others who have detailed knowledge and experience of the region’s rivers,
with guidance from experts in the process of environmental flow assessment. Such programs should include
research to better understand flow-ecology-livelihood links as well as how to proceed with limited knowledge
and improve relevant DSSs. Even if the initial results are uncertain, attempting environmental flow assessment,
utilizing teams of appropriately guided experts, would facilitate holistic approaches and assist interactions
between different disciplines. This would be a useful first step in the development of national and regional
expertise in environmental flow assessment.
6.4 Considering possible health impacts and the role of dam operation in mitigation
In Africa there are particularly strong links between diseases and the construction of infrastructure, including
dams. However, the public health impacts arising from the construction and operation of dams are often
poorly understood and often overlooked during planning and operation of dams. Public-health agencies are
often not involved or only marginally involved. As a result, adverse disease impacts are often passed to health
authorities to deal with, rather than being more fundamentally incorporated into the planning process.
Inadequate consideration of public-health impacts can seriously reduce the envisioned benefits of large dams
and, in some circumstances, may undermine their sustainability (Section 3.6).
An innovative approach to disease control that has not been widely explored in Africa is the use of dam
management as a form of environmental control, for example, reducing malaria by managing reservoir water
levels to reduce mosquito breeding habitat. Research conducted in Ethiopia has shown that at least under
certain circumstances, manipulation of water levels has the potential to reduce breeding habitat by drying
out puddles around reservoir shores (see Appendix 1, Use of reservoir operation as a tool for malaria control).
DSSs can contribute significantly to both improved understanding of the complex links between disease
vectors and reservoirs and also better management of likely health impacts. Many models have been developed
that simulate the mechanisms underlying disease vector dynamics and their relations to the environment.
Although much research still needs to be undertaken, these models enable a better understanding of the
mechanisms underlying disease transmission both generally and also in specific geographic environments.
As such, they provide a starting point for predicting the likely impacts prior to dam construction and the
impacts that may arise from specific interventions to reduce transmission.
By quantifying the likely health impacts, DSSs can contribute to Health Impact Assessments (HIAs),
which are similar to EIAs but focus on health (WHO 1999). They provide a systematic approach for
screening, assessing, appraising and formulating management plans to address key public health issues
associated with development projects, including dams. However, HIAs are generally under utilized as
32