In February 2010, the Water Environment Research Foundation (WERF; Alexandria, Va.) released a report on the implications of climate change on the wastewater and stormwater sectors. The report, Implications of Climate Change for Adaptation by Wastewater and Stormwater Agencies (CC2R08), is part of a 5-year WERF program on the potential effects of climate change on wastewater and stormwater utilities.
The report says four major types of local climate change have the potential to affect wastewater and stormwater sectors. They are
· sea-level rise,
· warmer and shorter winters,
· warmer and drier summers, and
· more-intense rainfall.
These types of changes have many implications, such as an increased risk of storm and flood damage to facilities and frequently altered biology and chemistry of receiving waters.
If sea levels rise, there is a risk of increased intensity of coastal erosion and coastal storms. Sea-level rise may alter the biology and chemistry of brackish waters and increase the salinity and acidity of coastal waters.
Warmer and shorter winters increase the risk for earlier spring melt of snow and runoff. Warmer temperatures and fewer extreme cold days can alter the biology and chemistry of receiving waters.
Warmer and drier summers, which are expected over most of North America, could lead to more hot-weather operating challenges, increased water temperatures, and lower dissolved-oxygen concentrations.
Finally, warming is expected to lead to more-intense rainfall, with an increased risk of flooding, sedimentation, bacterial contamination, and more-frequent wet weather operating challenges, among other things.
These are only potential risks, and their magnitude and timing are uncertain, the report says. Nevertheless, it notes, adaptation planning is an important approach to use to identify the risk of the events and to plan accordingly.
The WERF research team identified future research needs for the wastewater and stormwater sector to pursue to adapt to climate change. To approach adaptation planning, the team recommended a risk-management framework based on the familiar steps of risk identification, risk assessment and characterization, and risk management (adaptation). In the climate arena, this is referred to as a “bottom up,” or threshold, approach to adaptation planning.
While some of the identified risks imply that wastewater and stormwater agencies already should be implementing some types of adaptive strategies, other types of risks may not require significant changes in facilities or operations for decades, according to the report.
Before implementing adaptation strategies, it is prudent first to undertake a vulnerability analysis to assess how soon the effects may materialize at a level that represents a meaningful threat to existing or planned facilities and operations, according to the report. This analysis will help define the most appropriate adaptive responses, the report says.
Since greater uncertainty will exist for planning long-term infrastructure projects, adaptation planning may be a cross-generational strategy, the report says. The sustainable path for infrastructure planning means that current managers will lay the foundation for future generations to re-evaluate the presumed useful lives of wastewater and stormwater assets.
The report states that wastewater infrastructure planners will need to assess how things are changing, as well as assess how practices can best be adapted to meet these changes. Although adaptation planning includes elements of a long-term strategy, utilities are recommended to begin moving on these items in the near term, the report says.
The report, written by John Cromwell of Stratus Consulting (Boulder Colo.), can be obtained from WERF’s Web site, www.werf.org. It is free to WERF subscribers and costs $50 for nonsubscribers.
©2010 Water Environment Federation. All rights reserved.