Presentation on theme: "Louisiana Coastal Erosion. The problem LA contains approximately 40% of the nation's wetlands and experiences 80% of the nation's coastal wetland loss."— Presentation transcript:
The problem LA contains approximately 40% of the nation's wetlands and experiences 80% of the nation's coastal wetland loss. LA is losing 25 to 35 square miles of wetland per year and the highest rates are occurring in the Barataria and Terrebonne basins at 10 and 11 square miles per year. At current land loss rates, an area the size of Rhode Island will be gone by 2050.
With 500 million tons of waterborne cargo passing through Louisiana's system of deep-draft ports and navigational channels, Louisiana ranks first in the nation in total shipping tonnage. - If present land loss rates continue, more than 155 miles of waterways and several of the ports will be exposed to open water within 50 years. LA's commercial fisheries are the most bountiful of the lower 48 states, providing 25% - 35% of the nation's total catch. LA is first in the annual harvest of oysters, shrimp, crabs crawfish, red snapper, wild catfish, sea trout and mullet. - By 2050, the annual loss of commercial fisheries will be nearly $550 million. For recreational fisheries, the total loss will be close to $200 million a year.
Problem (continued) Wetlands and barrier islands provide a protection barrier from strong winds and hurricanes: every 2.7 miles of wetlands absorbs one foot of storm surge. Data from past hurricanes indicates that the loss of every one-mile strip of wetlands along the coast, results in an estimated $5,752,816 average annual increase in property damage. Between 60 and 70% of LA's population lives within 50 miles of the coast. Infrastructure along coastal LA is estimated at $150 billion.
Economic Impacts to LA and the Nation LA's wetland loss could cost the nation $36.6 billion from lost public use value over the next 50 years. 18% of U.S. Oil Production; 24% of US natural gas production originates, is transported through, or is processed in LA coastal wetlands. - One fourth of our nation's energy supply depends on the support facilities in South Louisiana. - LA's oil and natural gas industries have a value exceeding $16 billion a year. Over 20,000 miles of pipelines are located in federal offshore lands and thousands more inland. - Wetlands protect pipelines from waves and insure that the lines stay buried in place. - When pipelines are exposed to more waves and storms, it becomes more likely that they will pose a threat to passing water traffic.
Annual precipitation and runoff for continuous corn watersheds, no-till and conventional tillage, 1979-1988 yearPrecipitation mm runoff no-till mm runoff conventional mm 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1124 1175 1057 889 1027 909 929 966 841 854 3.81 4.90 0.14 0.00 0.00 2.31 0.01 9.23 0.15 0.03 140.2 312.8 142.2 - - - - - - - Source: W M Edwards: Soil structure: process and management in Lal & Pierce: Soil management for sustainability, 1991.
How erosion occurs Storms often cause coastal erosion, in particular those storms that have high winds and big waves. These waves eventually wash away the soil and rocks that are built up in the land. What is now the coast in many areas, used to be miles away from the coast.
In Louisiana hurricanes are a big contributor to the erosion of our coast. When these storms come, their high winds and wave take out the barrier islands that protect the coast. After years of hurricanes all of the old barrier islands have disappeared and one of the new islands protecting our state is Grand Isle. Unfortunately this island may not have much time left.
A COMMON KNOW FACT No matter what,beaches suffer from a natural retreat in its shoreline. This is not what makes erosion a problem is human made stuctures. When a person builds a structure on the shoreline it interrupts the natural process that a beach goes through.
A Kick In The Groin Property owners put up rock walls along the shore called a groin. This at the time was a simple solution to progressing erosion. It worked by slowing the currents down and gathering sand on the up drift side of the wall. But it was soon discovered that these structures helped the property owners and took away from the beaches.
Solution Already in effect are the piles of rock often called jetties that reduce that break down the waves before they reach the beach, this had saved a lot of the beach and Grand Isle and it is possible that itwould do the same in other areas.
Solution (continued) A possible solution is that all areas with beaches make a setback point. This is the point where the shoreline is estimated to be in 100 years. This would prevent building structures too close to the beach.
Breakwaters Another simple and affective solution is building offshore breakwater structures that will reduce the wave energy before it reaches inland, therefore reducing the amount of impact that a wave has on the inland. This will decrease the amount of land lost.
Our Solution Louisiana’s coastal erosion is caused by the diversion of the Mississippi river. It is a known fact that all of our land was built up by sediment that flowed down the Mississippi. If we were to diverge the Mississippi back to its normal route it is possible that it would build our lands back up.