Salt Water Intrusion

When it comes to Louisiana, there is no one reason for coastal land loss. Causes are both natural and man-made, but when those forces combine, they are detrimental to Louisiana’s coast. One example contributing to these synergistic forces is known as salt water intrusion.

Facts about Salt Water Intrusion: [4]

  • May occur in freshwater systems like aquifers or coastal marshes.
  • Is the movement of saltwater into interior areas or underground sources such as aquifers of freshwater marsh.
  • Most common in coastal regions, where freshwater is displaced by the inland movement of saltwater from the ocean.
  • Can also occur inland, far away from an ocean, as freshwater is pumped out from underground reservoirs and the salt-laden water from surrounding salty layers of the earth flow in.
  • Most common cause of saltwater intrusion is the pumping of freshwater from wells near coasts.
  • Climate change can increase saltwater encroachment along coastal regions as sea level rises.
  • Increased salinity of coastal freshwater can threaten the plant life and wildlife of coastal areas, destroy habitats such as marshes, and force the abandonment of drinking-water supplies.

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Coastal Louisiana is currently experiencing higher than expected salinity in traditionally freshwater marshes, waterways, and reservoirs [1]. It is possible for wildlife to adapt to locally saline conditions, but that is a process that requires time. A study by two professors at the University of Louisiana at Lafayette concluded:

  • Resident marsh fishes have genetic adaptations for localized salinity conditions [1].
  • Continued adaptation will be most successful if salinity increases gradually [1].
  • The existence of adaptation to salinity tolerance will be most important in aiding survival during surges of high salinity, such as those associated with hurricanes [1].

At the same time that sea level is rising, man-made actions are intensifying salt water intrusion through [4]:

  • Canal dredging, including oil and gas access canals
  • Channelization or straightening of natural waterways
  • Construction of levees for flood control
  • General development activities in the coastal zone

CWPPRA hydrologic restoration projects help reduce the inland march of salt water. Culverts and pumps restore the flow of freshwater into marshes, while locks and weirs create “one-way” channels out of the marsh that salt water can’t access.

Sources:

[1] Leberg, P. and Klerks, P. 2004. Final Report: Saltwater Intrusion On The Gulf Coast: An Assessment Of The Interactions Of Salinity Stress, Genetic Diversity And Population Characteristics Of Fish Inhabiting Coastal Marshes. University of Louisiana at Lafayette (ULL). Available: https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/5385 [May 22, 2018].

[2] Spatafora, James. 2008. Saltwater Intrusion of Coastal Aquifers in the U.S. Available: http://kanat.jsc.vsc.edu/student/spatafora/default.htm#homepage  [May 22, 2018].

[3] Encyclopedia.com. 2018. Available: https://www.encyclopedia.com/environment/energy-government-and-defense-magazines/saltwater-intrusion [May 22, 2018].

[4] Southern Regional Water Program. 2018. Louisiana Environmental Restoration. Available: http://srwqis.tamu.edu/louisiana/program-information/louisiana-target-themes/watershed-restoration/ [May 22, 2018].

[5] Fowler, Kristen. “Saltwater Intrusion – EnvS 546 Univ of Idaho”. ” 23 April 2016. Online video clip. YouTube. Accessed on 24 May 2018. <http://www.youtube.com/watch?v=puSkP3uym5k>

[6] PBS Newshour. “Testing the limits of saltwater intrusion”. 17 September 2015. Online video clip. Youtube. Accessed on 24 May 2018. https://www.youtube.com/watch?v=75CoHNQVbY8

[7] LSU AgCenter Video Archive. “Saltwater intrusion threatens rice acres”. 8 Jan 2016. Online video clip. Youtube. Accessed on 24 May 2018. https://www.youtube.com/watch?v=Z4TGPtq4bD0

[8] Stanford Alumni. Rosemary Knight, “Sentinel Geophysics: Imaging Saltwater Intrusion from Monterey to Santa Cruz”. 2 April 2014. Online video clip. Youtube. Accessed on 24 May 2018. https://www.youtube.com/watch?v=k4XcBx7OT3Y