Approach
This approach addresses the need to consider future climate conditions in the design and management of wetland restoration. Modeling efforts show a high degree of uncertainty in parameters such as groundwater recharge and discharge, with the possibility of both increases and decreases. Like natural wetlands, designed wetlands will also be influenced by extreme precipitation and flooding as well as longer drought periods between rain events. Increased uncertainty in the hydrologic regime (especially the amount and timing of precipitation) and outputs (such as evapotranspiration, longer growing seasons, and anthropogenic withdrawal) will affect water levels and soil saturation in unpredictable ways that may vary from site to site and from year to year within a site. In addition, there is a need to augment traditional hydraulic design analysis of system responses to individual, conceptual extreme events, such as a “100-year flood”, which are occurring more frequently, with more detailed system response to long simulation periods, which give a more detailed and accurate assessment of wetland conditions and performance over time. Consideration of future hydrologic regimes in the up-front design of wetland restoration will increase the likelihood of their success in meeting performance criteria and providing desired ecosystem services.
Tactics
- For new wetland creations, increase habitat heterogeneity by increasing amount of edge through creation of irregularly-shaped shorelines (i.e., higher perimeter-to-area ratio), and increasing topographic/elevational heterogeneity.
- Incorporate long-term dynamic simulations into hydrologic and hydraulic analysis to simulate wetland response to a changing climate, e.g., changing 100-year floods and five-year storms.
- Design, construct and manage engineered wetlands in low-lying former agricultural areas to perform desired ecosystem services (e.g., flood control, sediment retention, nutrient removal, and fish and wildlife habitat).
- Adjust the location and size of wetland areas to new or changing water levels, such as moving riparian areas up or downslope to match current or future conditions and/or increasing the sinuosity of stream channels.
- Reduce excessive wave disturbance in impoundments by planting shelterbelts, artificially lowering water levels, creating artificial reefs at a distance from the shoreline in about 1 m of water, or deploying floating timber booms.
- Install artificial floating wetland islands (floating treatment wetlands) in storm water ponds and reservoirs to improve water quality of effluent, enhance fish and wildlife habitat, and reduce shoreline erosion.
Strategy
Strategy Text
This strategy outlines approaches to facilitate ecosystem adjustments to cope with altered hydrology, water budget components (inputs, outputs, and storage of water) and water quality. Managers face both challenges and opportunities from a periodic lack of water (e.g., from drought and higher evaporation) as well as excess water (e.g., from larger precipitation events) that go beyond the historical range of variation in both magnitude and duration. Wetland managers will therefore need to adjust systems to maximize desirable ecosystem functions despite altered hydrology. This adjustment includes all components of wetland systems such as flood storage capacity, site nutrient cycling, as well as the habitat suitability of plants, wildlife, and aquatic species. Adjusting wetland ecosystems to climate changes applies equally to natural areas, as it does to wetland creations and enhancements, and existing hydrologically managed systems (e.g., lakes, impoundments, and rivers regulated by dams and other hard infrastructure). Proactive consideration of hydrologic change can help managers reduce future risks and take advantage of opportunities to sustain hydrologic functions into the future.