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Environmental Atlas of the Lake Pontchartrain Basin

Lake Pontchartrain Atlas Home
Lake Pontchartrain Atlas:
Preface
Table of Contents
Introduction
Environmental Overview
Environmental Status & Trends
Restoration
Physical Environments
Basin Geology
Biological Resources
Environmental Issues You are at the Environmental Issues section of the Environmental Atlas of Lake Pontchartrain
Bibliography
Resources
Contributors
Acronyms
Contact:
Jack Kindinger
Environmental Issues: Coastal Land Loss | Shoreline Change and Rates | Urbanization | Aggregate Dredge Holes | Dredge Pit Characterization | Bonnet Carré Diversion | Water Quality | Sediment Quality & Dispersal

Environmental Issues - Shoreline Change and Shoreline Change Rates

Contributors: Zganjar, Westphal, McCarty, Bridges, Penland

Shorelines compiled in this map were derived from either topographic or near-vertical aerial surveys conducted between 1850 and 1995 (Figure 10 a, b and c). The high-water line is used as the official shoreline on cartographic data and is interpreted and determined on near-vertical aerial photographs according to the location of the wet and dry beach contact or the high-water line. To evaluate change in shoreline position, shore-normal transects were constructed at approximately two minute intervals of longitude or latitude and used to measure the change in location of two corresponding shorelines in different years (Figure 11). Average rates of movement were calculated by dividing absolute measurement by elapsed time. Tables 7 and 8 present the transect measurements and shoreline change rates for Lake Borgne. A negative (-) sign signifies landward shoreline movement or erosion and no sign (positive) signifies a lakeward shoreline movement or progradation.

Figure 11: 1850 vs. 1995
Map showing shoreline change rates of Lake borgne from 1850 to 1995 and lcoation of transects.

Figure 11: Location of shore-normal transects for Lake Borgne.

Table 7: Shoreline Movement in Meters
Transect
1850-1995
Rate
(m/yr)
1930-1995
Rate
(m/yr)
1960-1995
Rate
(m/yr)
1 -207 -1.4 -26 -0.4 -35 -1.0
2 -272 -1.9 -56 -0.9 -43 -1.2
3 -262 -1.8 -69 -1.1 -34 -1.0
4 -202 -1.4 -119 -1.8 -57 -1.6
5 -202 -1.4 -132 -2.0 -13 -0.4
6 -272 -1.9 -137 -2.1 -66 -1.9
7 -209 -1.4 -172 -2.6 -63 -1.8
8 -352 -1.4 -21 -0.3 -20 -0.6
9 -652 -2.4 -175 -2.7 0 0.0
10 -767 -4.5 -206 -3.2 -12 -0.3
11 -1217 -5.3 -380 -5.8 -320 -9.1
12 -467 -8.4 -306 -4.7 -241 -6.9
13 -527 -3.2 -398 -6.1 -317 -9.1
14 -239 -3.6 -120 -1.8 -67 -1.9
15 -257 -1.6 -233 -3.6 -76 -2.2
16 -387 -1.8 -164 -2.5 -98 -2.8
17 -427 -2.7 -145 -2.2 -57 -1.6
18 -410 -2.9 -135 -2.1 -29 -0.8
19 -356 -2.8 -192 -3.0 -53 -1.5
20 -452 -2.5 -260 -4.0 -58 -1.7
21 -332 -3.1 -157 -2.4 -42 -1.2
22 -218 -2.3 -103 -1.6 -51 -1.5
23 -220 -1.5 -100 -1.5 -25 -0.7
24 -303 -2.1 -164 -2.5 -47 -1.3
25 -489 -3.4 -222 -3.4 -77 -2.2
26 -427 -2.9 -199 -3.1 -52 -1.5
27 -185 -1.3 -146 -2.2 -73 -2.1
28 -379 -2.6 -209 -3.2 -92 -2.6
29 -250 -1.7 -138 -2.1 -55 -1.6
30 -244 -1.7 -139 -2.1 -74 -2.1
31 -158 -1.1 -142 -2.2 -78 -2.2
32 -274 -1.9 -68 -1.0 -47 -1.3
33 -277 -1.9 -158 -2.4 -111 -3.2
34 -238 -1.6 -206 -3.2 -122 -3.5
35 -461 -3.2 -223 -3.4 -97 -2.8
36 -203 -1.4 -239 -3.7 -112 -3.2
37 -120 -0.8 -223 -3.4 0 0.0
38 -318 -2.2 -357 -5.5 -69 -2.0

Table 7: Measured change of shoreline position (m) along Lake Borgne for three time intervals and the corresponding shoreline movement rate (m/yr) for each transect.

Table 8: Average Shoreline
Movement in (m/yr) for Lake Borgne.
1850-1995 -2.40
1930-1995 -2.69
1960-1995 -2.17

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