Divert/block/stop saltwater inputs
Overall effectiveness category No evidence found (no assessment)
Number of studies: 0
Background information and definitions
Marshes and swamps may be threatened by inputs of the wrong type of water. This action involves limiting inputs of salty water to marshes or swamps of lower salinity. Clearly, this includes keeping brackish, saline and hypersaline water out of freshwater sites. Less intuitively, it might also be desirable to keep hypersaline water out of brackish or saline sites. Both inland and coastal wetlands can suffer from excess saltwater inputs. Chronic inputs may be related to groundwater extraction (causing subsidence of coastal areas), construction of canals (which allow salt water to penetrate further inland), elongation of tidal creeks, and global sea level rise (Wang 1988; White & Kaplan 2017). Acute inputs can occur during storms and tsunamis.
Specific infrastructure to divert or block water includes pipes, channels, waterways, pumps, impoundments, plugs or dams. Intervention may be permanent (e.g. blocking input channels) or temporary (e.g. diverting saltwater inputs during storm surges).
Caution: Diversions could shift the problem to another habitat: a suitable recipient habitat, where impacts will be minimal, should be chosen. Consider potential negative impacts of reducing water and sediment inputs to the focal marsh or swamp.
Related actions: Plug/dam canals or trenches (freshwater marshes – brackish/salt marshes – freshwater swamps – brackish/saline swamps); Actively manage water level, including by adding fresh water (freshwater marshes – brackish/salt marshes – freshwater swamps – brackish/saline swamps); Divert/block/stop freshwater inputs; Build barriers to protect littoral habitats from rising water levels and severe weather (freshwater marshes – brackish/salt marshes – freshwater swamps – brackish/saline swamps).
Wang F.C. (1988) Dynamics of saltwater intrusion in coastal channels. Journal of Geophysical Research: Oceans, 93, 6937–6946.
White E. Jr. & Kaplan D. (2017) Restore or retreat? Saltwater intrusion and water management in coastal wetlands. Ecosystem Health and Sustainability, 3, e01258.