Ocean Waters Invade Our Coastal Ecosystems
Small changes make a big difference, and eight inches of sea-level rise along the East Coast of the USA impacts coastal cities and forests. Eight inches of rising seas over 70 years seems insignificant, and the current rate of sea-level rise, 3.4 millimeters per year, also seems small. But the cumulative effects of these changes are huge, and they alter the ecology of coastal forests and create headaches for coastal communities.
The problem is increasing amounts of saline groundwater. Geologists and hydrologists refer to the invasion of salt water into fresh groundwater as “saltwater intrusion.” Groundwater includes water in the clays and soils below our feet and water occupying pore spaces, or open spaces, in rocks like sandstone or limestone. These rock and soil zones are called aquifers when they fill with water. As aquifers turn increasingly salty, the land becomes less livable.
Jennifer Jurado, chief Climate Resilience Officer for Broward County, Florida, points out the greater Miami area is under threat. She talks about the encroachment of saltwater into the daily lives of local residents. “As the seas rise, that saltwater front moves farther inland.” It’s not a future threat, “It is already happening.” Communities are now raising funds for costly water treatment plants that turn salty water into drinking water, and taxpayers feel the pinch.
Flooding From Above and Below
Living at sea level increases a person’s exposure to tidal changes. Anyone who has lived on the Florida coast is familiar with king tides, which occur when the gravitational pull of the sun and moon align. This extra pull increases water levels during high tides by about one foot. This effect leads to a rise in nuisance flooding as saltwater floods neighborhoods and coastal ecosystems.
Each time seawater inundates a local community, some salty ocean water seeps into the ground, contributing to corrosion of the city’s water and sewage pipes. More flooding translates into more deterioration. Several years ago, Key West made the news as one of its neighborhoods reached the three-month milestone of continuous flooding.
However, there is a second factor contributing to the saltwater problem. Seawater does not always soak into the ground from above — it can flow in from below. Coastal Florida provides an example of saltwater intrusion due to its geology. Very porous limestones underlie much of the state. Because geology doesn’t stop at the coastline, these same porous limestones extend into the ocean. The high porosity within the limestones provides a direct flow conduit between the sea and coastal groundwater aquifers.
Fort Lauderdale faces some harsh realities as the city soaks in sewer waste. Six sewage spills leaked over 126 million gallons of raw sewage into the city waterways last year. Of course, the purpose of sewage lines is to separate nasty waste materials from the rest of the environment. But corrosion, enhanced by saltwater, turned the city’s sewage pipeline network into a leaky sieve. Groundwater leaked into the pipes, and raw sewage leaked out. Fixing the problem in Fort Lauderdale will take $1.4 billion they don’t currently have.
A recent article from NBC News discussed growing concerns about Ghost Forests along the USA’s Gulf Coast and Eastern Seaboard. The term “ghost forests” includes large stretches of white cedar forest where the trees turn from lush green to ghostly white. The trees are victims of salt poisoning from increasing inland flooding related to storm surge events and nuisance high tides.
When ocean waters are driven onshore during flooding events, not all the water returns to the ocean. Some of the seawater percolates through the soil, contaminating the inland water table. Trees in these inundated areas have reached and exceeded their maximum tolerance for saltwater, which is a testimony to the increased frequency and intensity of Atlantic Ocean storms and aggressive king-tide type flooding. Both are the direct result of climate change.
Coastal woodlands from the New Jersey shores to the Gulf Coast show the effects of stress related to saltwater intrusion. Where flat coastal plain topography keeps the forests hovering only slightly above the high tide line, small rises in sea level significantly impact coastal ecosystems.
Not all the ramifications of climate change are immediately apparent like hurricane winds and destructive storm surges. Below the ground, changes take place more slowly, gradually corroding our city’s infrastructure and poisoning our coastal ecosystems with saltwater.
King tides, bringing reality home (by WM House; ArcheanWeb)
Saltwater invades Florida’s water supplies (by WM House; ArcheanWeb)
More from ArcheanWeb:
ArcheanWeb: Exploring the environment, art, science, and more
ArcheanArt: Innovative digital art
ArcheanWeb On Medium:
EarthSphere Publication — Science and the environment
Dropstone Publication — Stories, life observations, art, and more
Reflections on life’s journey and thoughts on the Tao Te Ching — In Search of a Path
A fictional adventure about the origins of life — The Strings of Life
Ghost forests creep up U.S. East Coast (by Andrew Bossone and Maura Barrett, NBC News)
Rising Waters (Source: NASA)
Invading seawater jeopardizes South Florida’s drinking water, but we can lessen the threat | Editorial (Source: Sun Sentinel)