In March, the United Nations (UN) released the 2020 edition of its annual World Water Development report, with a special focus on climate change.
The report advises a combination of climate change mitigation and adaptation measures, covering such practical considerations as agriculture, finance, and disaster risk reduction.
Of particular interest to water professionals, the report offers specific recommendations for water resource management and infrastructure.
Upcoming Water Treatment Challenges
The report predicts a sharp increase in water eutrophication due to agricultural runoff, as well as increased water temperatures and reduced dissolved-oxygen contents, weakening water ecosystems’ ability to self-purify. According to the report, broad increases in both flooding and drought will amplify existing water stresses and lead to greater risks of water pollution and pathogenic contamination.
Urbanization, the report predicts, will increase water treatment costs and reduce its effectiveness as demands on water resource recovery facilities (WRRFs) grow, particularly in developing nations.
“Climate change may indirectly exacerbate groundwater contamination risk through the switch to unprotected on-site sanitation and open defecation when droughts limit water availability for flush toilets and proper hygiene practices associated with well-managed sanitation systems,” the report reads.
Infrastructure Problems Ahead
Experts predict in the report that risks to water infrastructure originate primarily from more intense and frequent floods, potentially causing damage or fouling. Another issue is variability in rainfall intensity and patterns which can make current infrastructure, designed according to flood standards that are growing increasingly outdated, obsolete.
However, the report notes climate change effects will merely exacerbate a broader, worldwide issue of ageing infrastructure.
“The issue manifests itself through sedimentation, increased operation and maintenance costs, structural changes, increasing risks of breakage, and overall operational efficiency decline as a structure approaches its design life,” the report reads. “But ageing is also influenced by the changing river inflow variability associated with climate change.”
According to the report, countries also increase their susceptibility toward climate change by neglecting to decommission aging dams when necessary. Although many countries have begun removing dams, they are often small dams with little environmental impact, authors write. The report notes that even large dams often have limited or no value, and while their removal may be a lengthy and costly process, it can have positive long-term implications.
Solutions For An Uncertain Future
The report emphasizes the need for “green,” nature-based solutions, which are often less expensive and more robust than conventional, “grey” water management infrastructure. Experts recommend investing in hybrid approaches that make the best use of both green and grey infrastructure.
Authors also discuss other solutions for drinking water and wastewater management, such as incentivizing dry- and low-flush toilets, implementing small-bore and shallow sewers, investing in water reclamation, recycling, and desalination projects, and focusing research on atmospheric moisture harvesting.
Read the full, open-access report at the UN website.
— Will Fowler, WEF Highlights
June 9, 2020
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