Using Data to Help Characterize and Plan for Future Climate Variability in the Metro Atlanta Region

Water supply, water quality and watershed management are key areas of planning in the Metro North Georgia Water Planning District (Metro Water District). The Metro Water District covers a 15-county region including and surrounding the city of Atlanta, and is responsible for developing plans that address and plan for water supply, wastewater and watershed management issues. These plans are adopted by water utilities and local governments and enforced by the State of Georgia through water permits. By evaluating and analyzing the potential vulnerability posed by climate variability in these areas, utility managers can be better informed when engaging in long-term planning.

The Metro Water District initiated a utility climate resiliency study to assess the potential impacts of climate variability on the region's water resources and infrastructure. By identifying and characterizing potential climate variability impacts out to the year 2050, the Metro Water District was able to develop a suite of adaptation measures to address and mitigate risks to water resources and infrastructure.

The study developed a set of potential future climate scenarios to look at possible impacts to water resources and risks to water infrastructure. These scenarios relied on a combination of global climate model (GCM) projection data sets as well as historically available climate data. The GCM projection datasets included published climate model projections for future air temperature and precipitation. The GCM data were pooled into five different ensembles to develop future climate scenarios (central tendency, hot/dry, hot/wet, warm/wet, warm/dry) for use in subsequent analyses. The historical analysis included continuous monthly historical climate records for each calendar month from 1930 - 2013 for temperature and 1900 - 2013 for precipitation.

The future climate scenarios helped assess climate impacts on the Metro Water District's water resources and quantify the region's vulnerability - in terms of water demand, supply, water quality, watersheds and infrastructure. The study also included recommendations and adaptation strategies that could potentially be implemented by utilities and local governments to address major risks identified to water, wastewater and stormwater systems and infrastructure.

In addition to long-term planning using the climate resiliency study, the Metro Water District also relies upon short-term information presented by the US Drought Monitor, the National Weather Service Forecast Office and Climate Prediction Center, USGS National Water Information System, and the US Army Corps of Engineers to evaluate current water supplies and potential for changes in water supply levels in the near term. For example, Georgia and Metropolitan Atlanta experienced a severe drought during early 2016 through mid-2017. This drought included a 12-month period with the lowest inflows into Lake Lanier, the largest water supply source for Metropolitan Atlanta, and also impacted local smaller reservoirs. The Metro Water District continually evaluated climate predictions and communicated with local utilities on management practices to determine approaches to help manage supplies throughout the drought.