Impacts of Climate Change and Variability on Water Resources in the Southeast USA
- Climate change is affecting the southeastern USA, particularly increases in rainfall variability and air temperature, which have resulted in more frequent hydrologic extremes, such as high‐intensity storms (tropical storms and hurricanes), flooding, and drought events.
- Future climate warming likely will increase water loss through evapotranspiration (ET) due to increased evaporative potential and plant species shift. Greater ET can decrease total streamflow, groundwater recharge, flow rate, and regional water supplies.
- Water supply stress is projected to increase significantly by 2050 due to hydrologic alteration caused by climate change and increased water use by key economic sectors, such as domestic water supply, irrigation agriculture, and power plants. Water supply stress will become most severe in the summer season when normal rainfall is typically not sufficient to meet evaporative demand of the atmosphere.
- Declining runoff and increasing demands for water resources are likely to increase the pressure on the existing reservoirs, leading to deeper and longer lasting drawdowns.
- Runoff and soil erosion potential are projected to increase in some areas due to changes in rainfall that either increase rainfall erosivity or decrease vegetative cover protection.
- Inland water temperature is projected to increase with increases in air temperature, resulting in possible adverse impacts on coldwater fish habitat in the Appalachians.
- Salinity intrusion in coastal fresh water systems likely will increase in response to sea level rise and decrease of fresh water inputs from uplands due to climate change. Flooding related to sea level rise may also threaten coastal infrastructure in low lying areas.
- Ecosystem restoration, including afforestation, has the potential to mitigate or reduce adverse impacts of hydrologic extremes (droughts or floods) and water quality caused by climate change.
- Best management practices (BMPs) should be adjusted and enhanced to increase watershed resilience to likely adverse impacts of climate change on water quantity and quality.
- Programs to increase water‐use efficiency, to use recycled water, and to increase water storage capacity should be developed to help alleviate water supply stress.
- Large knowledge gaps exist about how future climate change and other stressors‐‐such as human population growth, land use change, energy security, and policy shifts‐‐will interactively affect both surface and ground water availability.
- Consequences of proposed adaptation management options, such as increase in irrigated agriculture and bioenergy development, must be carefully evaluated to maximize their effectiveness and cost‐benefit.