Research from scientists at Indiana University and Louisiana State University reveals new details regarding the part that humans have played in a large-scale land loss in the Mississippi River Delta - crucial information in determining solutions to the crisis.
The study, which was published in Nature Sustainability, compares the effects of various human actions on land loss and explains historical trends.
Until now, scientists have been unsure about which human-related factors are the most important, and why the most rapid land loss in the Mississippi River Delta occurred between the 1960s and 1990s and has since slowed.
Mississippi River Delta Study Reveals Which Human Actions Contribute To Land Loss
"What we found was really surprising," said Doug Edmonds, the Malcolm and Sylvia Boyce Chair in the Department of Earth and Atmospheric Sciences at Indiana University Bloomington, as per ScienceDaily.
It's tempting to blame the land loss crisis on dam construction in the Mississippi River Basin; after all, dams have significantly reduced sediment in the Mississippi River. The current Mississippi River Delta was formed by sediment deposition from the river near the Gulf Coast over the last 7,000 years.
The delta, however, is no longer accumulating sediment as a result of human efforts to harness the river and protect communities.
As a result, coastal Louisiana has lost about 1,900 square miles of land since the 1930s, according to the Louisiana Coastal Protection and Restoration Authority.
Many researchers believe it is the result of different human interventions in the delta, including dam building, flood control levee installation, and subsurface resource extraction.
According to the study, dam construction accounts for only about 20% of land loss in the Mississippi River Delta, while levee construction and extraction of subsurface resources such as oil and gas account for 40%.
The study also suggests that the most rapid land loss and the recent slowdown may be linked to a decrease in subsurface resource extraction.
LSU researchers Robert R. Twilley, Samuel J. Bentley, Kehui Xu, and Chris Siverd also contributed to the study.
To conduct their research, researchers re-created land loss in the Mississippi River Delta's Barataria Basin. They used a model that describes the sediment budget, which is the balance among sediment coursing in and out of a coastal region.
The 2023 Coastal Master Plan for Louisiana takes precedence rebuilding the processes that naturally build land in the delta.
The Mid-Barataria Sediment Diversion, worth more than $2 billion, will divert sediment and water from the Mississippi River into the adjacent Barataria Basin.
Also read: Island Creation in the Maldives Could Counteract Land Loss Due to Sea Level Rise
Human-caused Land Changes
The primary threats to 85% of the species on the IUCN's Red List of threatened and endangered species are habitat loss and fragmentation, as per Earth.org.
Agriculture is a major contributor to this, as vast swaths of highly productive habitats like forest, meadow, and wetland habitats are cleared to make way for fields and grazing land.
Crop monocultures encourage low genetic biodiversity, pest species dominance, and crop susceptibility to disease by homogenizing agricultural ecosystems (i.e., a low variety of plant species and supported wildlife).
In places such as the USA, 75% of processed foods in supermarkets contain genetically modified ingredients, including 92% of maize and 94% of soybean products.
Because these crops are cloned, a single disease or pest can wipe out an entire field. The resulting vulnerable agroecosystem increases reliance on pesticides, herbicides, and fertilizers to promote crop growth and prevent damage.
Every year, more than 68 billion tonnes of topsoil are eroded at a rate 100 times faster than it can be replenished naturally. The soil, laden with biocides and fertilizer, ends up in waterways, contaminating drinking water and protected areas downstream.
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