Approach
This approach targets wetlands that will be impacted by changes in hydrologic regimes due to altered precipitation patterns and extreme precipitation and drought events. Hydrologic regimes within wetlands reflect the frequency, magnitude, and duration of high and low flow events. These fluxes in hydrology are influenced by water inputs, the storage capacity, and output components of the wetland’s water balance. Where hydrologic connectivity of wetlands to adjacent streams is diminished due to water control structures or diversions, more frequent prolonged droughts may further degrade wetland function and quality. Mismatches between extreme flood timing, phenology, and other biologic processes may also occur and are a concern to managers. Restoring hydrologic connectivity and water storage in wetlands can help mitigate the impacts of altered water budgets and extreme flooding throughout the watershed. While land use management alone cannot fully mitigate changes to water balances at broader spatial scales due to the more significant forces of climate change, local-scale land use management that focuses on runoff reduction, improved infiltration rates, and base flow management may reduce the impacts of climate-induced drought.
Tactics
- Use ditch plugs, fill ditches, or disable drain tile to increase residence time of water in disturbed wetlands.
- Where roads cross wetlands and streams, install adequately-sized drainage structures and stream crossings based on the upper-range of anticipated future conditions.
- Remove or modify restrictions that inhibit longitudinal flow between upstream and downstream habitats, in order to enhance aquatic organism migration to more favorable habitats (e.g. upstream, seasonal habitats, off-channel or cool-water areas).
- Use appropriate restoration techniques for the site, choosing from options that range from process-based (using natural hydraulics) to form-based (hardened infrastructure) options, to reconnect floodplains adjacent to incised river channels.
- Maintain beaver dams in headwater wetlands and avoid straightening stream channels to maintain a high water table in floodplain wetlands, reduce stream incision rates and encourage stream channel aggradation.
- Remove or modify dams and weirs where possible or manage water flow to mimic a more natural flow regime (i.e., frequency, magnitude, duration and timing of flood pulses) at both high flows and low flows.
- Remove legacy sediment to restore hydrologic processes to aggraded floodplains and depression wetlands.
- Amend or remove compacted soils to restore resident time and hydrologic processes in disturbed wetlands.
Strategy
Strategy Text
This strategy outlines resistance and resilience approaches to manage wetlands facing altered water budgets (water inputs, storage capacity, and outputs) due to a changing climate. Hydrology is a leading driver of wetland character and function and so expected changes to hydrologic regimes, hydrodynamics, and water levels concern wetland managers. Projections in the Upper Midwest indicate that wetlands will be influenced both by extreme precipitation and flooding events and longer drought periods between rain events. Some wetlands will become dryer and others may become wetter than long-term averages. Thus, managers face challenges (i.e., extreme flooding; drought) and opportunities (i.e., restored flood pulses to wetlands disconnected from surface or groundwater flows) in managing wetlands in the context of climate change. Restoring hydrologic connectivity has historically been a primary tactic of management efforts to restore wetlands lost or degraded by filling or draining due to land-use conversion and water extraction, and many of those same tactics can be applied or amended by wetland managers to meet climate change adaptation objectives. Restoring hydrologic connectivity and ameliorating saturated, anoxic conditions that limit decomposition also supports the capacity of wetlands to actively remove and sequester atmospheric carbon and mitigates future carbon losses.