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Shoreline/Wetland Changes
To determine shoreline and wetland change, digital analyses of historical
charts and aerial photographs were used. These were compared with recent
surveys and charts. Scientists can use information on shoreline
change over the past 100 years to predict areas of future change.
Shoreline erosion and wetlands loss are serious concerns in and around Lake
Pontchartrain. Causes of loss involve a complex interaction between natural
and human activities. Direct removal of land for canals, redistribution of
material for development and other processes that alter hydrography create
conditions of erosion, submergence and degradation of vegetation
(see classification of land loss).
In general, the utilization of Pontchartrain Basin's natural resources,
steady population growth (see below) and land
development over the past century have contributed to the shoreline and
wetland loss that we see today. Natural subsidence, a result of dewatering in
geologically young sediments, also contributes to the loss in currently unknown proportions.
Population Growth
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Historic Growth of New Orleans |
From its beginnings over two centuries ago, New Orleans has grown consistenly
in area and population. Its strategic position on the Mississippi River for
security and trade made the city the seventh largest in the country by the
early 1800's. Throughout the last two centuries, New Orleans has expanded
to currently cover approximately 175 square miles with over one million people
in the surrounding parishes.
This growth has brought significant change to the environment in the
Pontchartrain Basin. This change has been recorded in the sediments
of Lake Pontchartrain, which receives drainage from the Basin and directly
from the New Orleans area.
The sediments display a history of change in pollen assemblage, indicating a
transition from hardwoods to clear-cut grasslands and agricultural fields.
Trace metals concentrations in the sediments indicate an increase from background
of industrial-related contaminants.
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Expansion and Northward Migration: Sources - U.S.
Census Bureau and the Louisiana Population Center. 1997 and 2020 figures are estimated.
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In most recent times there has been a migration of population growth.
Historically the south shore of Lake Pontchartrain has seen rapid development,
whereas the marshlands and pine forests on the north shore have remained relatively
intact. Over time, farmland had been encroaching on the lake from the north.
With the construction of the Lake Pontchartrain Causeway across the lake and
Interstate 10 along the eastern shore, accessibility to the north shore has
been greatly improved. This accessibility has been reflected in a population
shift, where growth in the parishes along the north shore has caught up and
even surpassed that of the New Orleans area. This trend is expected to continue
and changes in environmental parameters associated with development should have an
impact on the conditions within the lake.
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U. S. Department of the Interior | U.S. Geological Survey
