Louisiana’s wetlands represent about 40% of the continental United States’ wetlands. They extend as much as 80 miles inland and along the coast for about 180 miles. Despite the abundance of wetlands in the state, Louisiana represents about 80% of the wetland losses in the United States.
Although not all wetlands are receding, when it comes to Louisiana, it is highly likely for this area to lose these vital habitats in about 200 years. Reducing the losses has proved to be challenging and costly. Some organizations are putting appreciable efforts to protect the wetlands and to understand how to control wetland evolution.
Barrier Islands
The U.S. Geological Survey (USGS), in collaboration with U.S. Fish and Wildlife Service and university partners from Louisiana State University, conducted a joint field investigation and cooperative study to research the Louisiana coast and gather and interpret baseline information.
The Louisiana Barrier Island Erosion Study started in 1988 and focused on the processes that cause barrier island erosion. Scientists collected data sets on variables, including storm effects, water movement and dispersal of fine-grained sediments, soil development, marsh disintegration, and effects of land subsidence and sea-level rise. After synthesizing and comparing data sets, the data collected from representative sediment-starved and sediment-rich basins in Louisiana enhanced scientific knowledge of wetland functions. The goal is to improve scientific knowledge and thus improve the processes responsible for the creation, maintenance, and deterioration of coastal wetlands.
The Mississippi River Delta and its associated wetlands and barrier shorelines continuously change due to water movement, unconsolidated sands, and mud accumulation. Rivers deltas are the primary source of sediment erosion in a channel. As the river withdraws from the delta, they erode and deposit loose sediment into the river channel. Additionally, marine processes erode and rework the seaward margins of river deltas, which form sandy headlands and barrier beaches. Over time, segmented low-relief barrier islands form and are gradually separated from the mainland by shallow bays and lagoons.
The barrier islands of the Mississippi River Delta act as natural buffers by reducing the effect of ocean waves and currents on associated estuaries and wetlands. However, the environmental consequences of coastal erosion in Louisiana are notable and are at a rate of up to 60 feet per year. The USGS estimates that several barrier islands could disappear by the end of this century. Without a designated buffer, the wetlands along Louisiana’s delta plains would be exposed to the full force and the effects of the ocean, such as wave action, salinity intrusion, and storm surge.
Solutions
There are various solutions to address the gradual loss of barrier islands and wetlands along the Louisiana coast. Soft engineering methods such as barrier island re-nourishment have proven effective. However, these engineering methods can affect small communities, agriculture, and local industry. Hard engineering solutions can include the creation of new navigation channels, constructed sea walls, and breakwaters. A system of seawalls, levees, pumps, and other flood controls can help prevent catastrophic outcomes. However, natural barriers and wetlands act as “speed bumps,” which significantly decrease the impact of storms.