Climate change and the vulnerability to our drinking water
When we talk about ‘climate change’ in this article, we do not specifically mean global warming, though that does play a part. The climate of an area regularly goes through fluctuations, and we are currently experiencing an extreme in that cycle. Most folks refer to that as global warming. No matter what you call it, climate changes affect precipitation, the flow of water in watersheds, and the quality of marine and aquatic environments. As these changes occur, we can also expect to see changes in the agencies and programs that are designed to protect and manage these critical water resources.
In 2010, the Environmental Protection Agency (EPA) distributed a report from its Office of Water and Office of Research and Development, in which they reviewed some specific practices of water utility managemenat agencies across the country. The focus was on how they assessed their systems for climate change vulnerability.
Climate Change poses a number of problems to water utilities, and there are uncertainties on how to downscale global models of climate change in order to understand how climate change really affects local systems. The EPA believes that some sort of climate change vulnerability assessment is an important component for any water resource manager to use in creating a plan for climatic and hydrological changes in their areas.
The EPA researchers identified ten water utilities who already had these vulnerability assessments in place at the time the research was being conducted. Many other water management agencies had interest in putting these practices in place but had either not published data from their efforts or had not actually done anything yet. Due to time and other constraints, they were only able to use 8 of these utilities in their report. Their point in reviewing these systems was to give other water utilities a basis for designing their own assessments.
They do not make any recommendations on which are the best practices, nor do they judge the systems. They merely review and summarize the efforts of these water utilities.
The eight Utilities in the review are as follows:
- East Bay Municipal Utility District (EBMUD); A water supply and wastewater utility serving 1.3 million customers.
- City of Boulder Utilities Division; A water supply and wastewater utility serving 113,000 customers.
- Denver Water; A water supply utility serving 1.3 million customers.
- Massachusetts Water Resources Authority (MWRA);A water supply and wastewater utility serving 2.2 million customers.
- New York City Department of Environmental Protection (NYCDEP); A water supply and wastewater utility serving 9.2 million customers.
- Portland Water Bureau (PWB); A water supply utility serving 860,000 customers.
- Lower Colorado River Authority (LCRA); A conservation and reclamation district that manages water supply along a 600-mile stretch of the Colorado River in Texas, operates six dams, and helps communities plan and coordinate their water and wastewater needs.
- Seattle Public Utilities (SPU); A water supply utility serving 1.35 million customers.
- Two Approaches to Assessing Climate Change Vulnerabilities
When it comes to assessing the effects of climate change, there are generally two different ways to discover the vulnerabilities of a particular system. There is a top-down modeling assessment approach, and a bottom-up threshold analysis approach. Water managers typically begin with one or the other, but eventually use both approaches, or at least elements from both approaches, in order to evaluate their system’s vulnerability to climate changes.
The top-down approach involves modeling future climate changes, such as temperature variances and precipitation levels, and evaluating the effects of those changes on the various water systems. This is the most resource intensive approach to assessing climate change, and usually involves partnering with an academic institution or consulting firm that has expertise in climate change modeling. Six of the utilities that were reviewed in this report utilized this approach, and there are three main subcategories of this modeling approach; scenario analyses, sensitivity analyses,
and paleoclimate data or historic climate observations to define temperature and precipitation
patterns for water system planning purposes.
Scenario Analysis involves defining different possible futures with different climate changes, and working down from a global model to a local model, and assessing each model for it’s water system’s vulnerabilities. This generally involves a lot of computing, take time, and uses a lot of resources.
Sensitivity Analysis involves creating scenarios with incremental changes in temperature and precipitation. This method does not involve using GHG emissions projections, using climate model projections, or downscaling climate model output, and can also be used in a bottom-up approach.
Paleoclimate or Historical Analysis involves using data from paleoclimate projections and historical observations to define patterns of water and temperature variations. This method often projects worst case scenarios and the utilities that used this method, only used it to compliment their other efforts.
The bottom-up approach is mainly qualitative and involves utilizing knowledge of the current water system, and evaluating the elements of the current system (or even elements that will be put into place) for potential vulnerabilities. This method can be used to identify critical failure thresholds of the various elements of a system, discover exactly what would cause these failures, and take steps to prevent such failures. Typically, a bottom-up approach involves less resources, and is done in house by people who have strong technical knowledge of the current water systems and by using data that is available. Two of the utilities reviewed utilized this bottom-up qualitative approach.
Constraints on Water Management Utilities
Many water managers face constraints on manpower or fiscal resources. Setting up vulnerability assessments take time and money, but for managers who are intent on making climate change a part of your management plans, there are ways to get started. If you are financially constrained, begin with a bottom-up approach. If you are short on human resources, but you have financial means, then try outsourcing the research.
Another major constraint on utilities is the political environment. Many water managers do not have the political support to engage in extensive climate change vulnerability assessments. In cases where there is little or no policy support, the EPA recommends that water managers begin by using a bottom-up approach to identify areas that need more extensive research done. Once you’ve identified areas that require additional research, it may become easier to garner political support.
Summary of Sources and Uses of Data
The data used by the utilities that were surveyed in this report came from the instrumental record, paleoclimate data, literature reviews, and climate projections from Global Climate Models. Climate projection data was typically the most computationally demanding source of information. The data from the various sources was then processed through various utility specific models to determine where the vulnerabilities of a system lay. Then the various utilities used the data gathered to design plans to compensate for the vulnerabilities. You can find out more specific information on the sources and methods by reading the the full report here.
After reviewing the aforementioned utilities, the EPA makes some recommendations for further study. They said, “Climate change is a complex issue and will require ongoing work to establish reliable practices for incorporating climate change into water utility decisions and planning.” The researchers posed these questions in order to develop this line of research and planning:
- How are decision makers and rate payers responding to these types of analyses?
- Would the results vary if different methods were used by the same utility?
- How do the different methods compare in effectiveness, over time?
- What other decisions, utility models, etc. need climate vulnerability assessments?
- How are vulnerability assessments being conducted for understanding climate
impacts on managing:
- Water quality?
- Intense precipitation and storms (stormwater, floods, wind)?
- Sea level rise?
Finally, the EPA suggests that water managers keep accurate records of their methods and experiences in climate change vulnerability assessments, in order to help create an industry standard of best practices in this area.
The field of climate change assessment is still quite young. As this new field of research develops, better and best practices are developing, too. If you are interested in how climate change could affect you and your family, then you should do some research into the methods being used to protect your water sources from climate change. Maybe you can help change policies in order to let your water manager conduct the appropriate research and take appropriate steps in preparing for climate change in your area. the EPA has to say about climate change Check out what and water here.
posted by mark contorno