Shoreline Erosion at Mad Island Marsh Preserve, Matagorda County, Texas

SHORELINE EROSION AT MAD ISLAND MARSH PRESERVE, MATAGORDA COUNTY, TEXAS

Webster Mangham, B.A.

Thesis Prepared for the Degree of

MASTER OF SCIENCE

UNIVERSITY OF NORTH TEXAS

August 2005

APPROVED:

Harry Williams, Major Professor Paul Hudak, Minor Professor and Chair of the Department of Geography Pinliang Dong, Committee Member Sandra L. Terrell, Dean of the Robert B. Toulouse School of Graduate Studies

Mangham, Webster, Shoreline Erosion at Mad Island Marsh Preserve, Matagorda

County, Texas . Master of Science (Applied Geography), August 2005, 44 pp., 5 tables, 29 figures, 4 appendices, 27 references.

The Nature Conservancy of Texas (TNC) is concerned with the amount of shoreline erosion taking place at its Mad Island Marsh Preserve (MIMP), located in Matagorda Bay,

Texas. The MIMP is a 7,100 acre nature preserve that borders the Gulf Intracoastal Waterway and is eroded by waves generated by barge traffic. TNC is concerned that erosion will shorten

Mad Island Bayou which may increase the salinity of Mad Island Lake; with detrimental effects on lake and marsh habitats. This study uses global positioning system (GPS) technology to map the current shoreline and geographic information systems (GIS) to determine ten year erosion rates (1995 – 2005). Results show that erosion is occurring at various rates along the shoreline as well as along the oxbow bend in Mad Island Bayou.

Webster Mangham

ii ACKNOWLEDGEMENTS

This project could not have been completed with out the help of Jared Laing (Nature

Conservancy of Texas) and the input from Paul Hudak (University of North Texas, Geography

Department Chair), Pinliang Dong (University of North Texas, Professor), and Reid Ferring

(University of North Texas, Professor). Special thanks to: Harry Williams (University of North

Texas, Professor) for ideas, revisions, and guidance; Bruce Hunter (University of North Texas,

Center for Remote Sensing and Spatial Analysis) for technical expertise; and Roger Mangham for fieldwork assistance, “protection,” and passing onto me a true love of Science.

iii TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS………………………………………………………………………iii

LIST OF TABLES.……………………………………………………………………………..…v

LIST OF FIGURES....……………………………………………………………………………vi

Chapter

1. INTRODUCTION.….………………………………………………………………….1

Introduction Study Area Previous Research and Ongoing Projects

2. METHODOLOGY.….………………………………………………………………..10

Shoreline Delineation Data Preparation and Fieldwork Error Data Analysis

3. RESULT...……………………………………………………………………………19

Overview WEST Section WEST ESCARPMENT Section CONCRETE MAT Section CENTER SECTION EAST Section OXBOW BEND Subsection

4. DISCUSSION………………………………………………………………………..29

Entire Study Area Recommendations Discussion of Methods Recommendations for Further Research

APPENDIX A……………………………………………………………………………………35

Williams’ One Year Monitoring Program Measurements

iv APPENDIX B……………………………………………………………………………………37

2005 GPS Shoreline Creation Error Measurements

APPENDIX C……………………………………………………………………………………39

1995 Shoreline Creation Error Estimates

APPENDIX D……………………………………………………………………………………41

Difference Between 1995 and 2005 Shorelines

REFERENCES…………………………………………………………………………………..42

v LIST OF TABLES

Page

1. Williams’ 48-year MIMP Erosion Measurements...... 7

2. Shoreline Description by Section...... 10

3. Root Mean Square Error Between ArcMap Measurements and Tape Measurements ... 16

4. MIMP Erosion Rates by Section and Rate Comparisons with two Previous Studies .... 19

5. Land Loss Calculations...... 20

vi LIST OF FIGURES

Page

1. Mad Island Marsh Preserve Study Area Map...... 2

2. MIMP Shoreline Showing Dredge Spoil Islands and Approximate Original GIWW...... 3

3. Close Up of the Oxbow Bend ...... 4

4. MIMP Study Area Divisions ...... 5

5. Williams' Base Map: Showing Letters Corresponding to Measurement Locations and Erosion Measurement Stake Locations (Every Fifth Shown)...... 7

6. Projected Location of the Reefblk Erosion Control Structure...... 9

7. Selected Section (WEST Section) of 2005 GPS Shorelines...... 11

8. Selected Section (CENTER Section) Showing 2005 Baseline GPS Shorelines and Transects ...... 12

9. Selected Section (CENTER Section) Zoomed in to Demonstrate Separation Between 2005 GPS Shorelines ...... 13

10. Selected Section (CONCRETE MAT Section) Zoomed in to Demonstrate Creation of Average 2005 Shoreline...... 14

11. Photograph of Williams’ Erosion Monitoring Stake ...... 15

12. Selected Section of Williams’ Stakes Demonstrating ArcMap and Tape Measurement Distances...... 16

13. Ground Control Point at the MIMP Office Building...... 17

14. Ground Control Points at Selected MIMP Road Intersections ...... 17

15. Selected Section (WEST Section) Showing Polygons Created Between the 1995 and 2005 Shorelines...... 18

16. WEST Section with 1995 and 2005 Shorelines...... 21

17. WEST Section Photograph ...... 21

18. WEST ESCARPMENT Section with 1995 and 2005 Shorelines ...... 22

19. WEST ESCARPMENT Section Photograph...... 23

20. CONCRETE MAT Section with 1995 and 2005 Shorelines...... 24

vii 21. CONCRETE MAT Section Photograph ...... 24

22. CONCRETE MAT Section Failure Photograph...... 24

23. CENTER Section with 1995 and 2005 Shorelines ...... 25

24. CENTER Section Photograph...... 26

25. EAST Section with 1995 and 2005 Shorelines...... 27

26. EAST Section Photograph ...... 27

27. BAYOU BEND Subsection with 1995 and 2005 Shorelines ...... 28

28. MIMP Erosion Rate Graph: Comparison Across Three Studies ...... 29

29. Recommended Changes to the Bayou Bend Section...... 31

viii CHAPTER 1

INTRODUCTION

Introduction

In November 1528, Cabez de Vaca learned the perils of the Texas coastline first-hand when he shipwrecked on what is believed to be Galveston Island; subsequently, LeSalle lost two ships in the Matagorda Bay in the 1860s. The treachery of the Texas coastline became legendary as settlement increased. Ship after ship was lost to the erratic nature of the shifting sand bars, unpredictable weather, currents, and tides.

The Texas coastline spans approximately 367 miles from Louisiana to Mexico (Texas

Almanac, 2005). Including the numerous wetlands, bays, and inlets, the actual mileage of the land/water interface is about 624 miles (Texas Almanac, 2005). Texas’ Gulf coast contains hundreds of miles of marshes, barrier islands, estuaries, and bays that support some of the United

States’ most productive fisheries (Texas Parks and Wildlife (TPW), 2005). Recently, environmental effects of urbanization and industrialization have become concerns in the Gulf coast region (United States Environmental Protection Agency (USEPA), 2002). It is widely known that these factors, along with upstream river damming, have exacerbated erosion problems on Texas’ coastline (Phillips et al., 2004).

Shoreline erosion problems are a major concern for managers of the Nature Conservancy of Texas’ Clive Runnells Mad Island Marsh Preserve (MIMP). This study uses geographic information systems (GIS) and global positioning systems (GPS) technology to calculate the erosion/accretion rate of the MIMP’s shoreline between 1995 and 2005. It also looks at variation of shoreline erosion rates based on shoreline type, as well as erosion rate comparisons with two previous erosion studies completed at the MIMP.

1 Study Area

The MIMP is located to the southeast of Collegeport, Texas on the eastern portion of

West Matagorda Bay ( Fig. 1 ). In 1989, Clive Runnells donated 3,148 acres, of what is now known as the MIMP, to the Nature Conservancy of Texas (TNC, 2004). In 1993, TNC acquired

3,900 additional adjacent acres to make the total area of the preserve 7,148 acres (TNC, 2004).

Additionally, the MIMP connects to TPW’s 5,700 acre Mad Island Wildlife Management Area

(TNC, 2004).

Figure 1. Mad Island Marsh Preserve Study Area Map

The MIMP has approximately 2,500 meters of coastline that it shares with the Gulf

Intracoastal Waterway (GIWW). This section of the GIWW was constructed in 1941 by

2 dredging the bottom of the bay and depositing spoils on the southern side of the waterway

(Fig. 2 ) creating artificial barrier islands

(Williams, 1993b). Originally, the GIWW was 30.48 m wide and 3.66 m deep ( Fig. 2 ).

Studies in the 1990’s revealed that erosion caused by barge traffic had enlarged the

GIWW to about three times its original width

(Williams, 1993). Other studies have Figure 2. MIMP Shoreline Showing Dredge Spoil Islands and established that waves generated by passing Approximate Original GIWW ships cause shoreline erosion (Amromin et al., 2004), and in 2001 there were 101,818 (one-way) barge trips through the GIWW (American Society of Civil Engineers, 2004). This number does not include the thousands of recreational boats that traverse the GIWW each year.

Tropical storms and hurricanes are not uncommon to the study area. According to the

National Oceanic and Atmospheric Administration (NOAA) and Unysis weather data, four tropical storms and two hurricanes have made landfall in the Matagorda Bay area since 1991

(Unysis, 2005; NOAA, 2005). Tropical Storm Fay (2002) and Hurricane Claudette (2003) caused extensive flooding on the MIMP. Hurricane Claudette flooded the bottom section of the

MIMP’s office building, destroyed the roof, and caused widespread water damage to the structure. Single event storms can have acute impacts on shorelines and large-scale, high-energy events can erode significant amounts of coastline in a very short period of time (Morton et al.,

1995).

3 Bays, wetlands, bayous, estuaries, marshes, and lakes are some of the most productive, species rich, and diverse habitats in the world (Halsted, 2003). The MIMP is comprised of a network of salt marshes, open water estuaries, freshwater and brackish lakes, wetlands, riparian hardwood communities, rice fields, and coastal prairies (Halsted, 2003). The estuaries and wetlands on the preserve provide an important habitat for many aquatic organisms that are both recreationally and ecologically important (Halsted, 2003). They include southern flounder

(Paralichthys lethostigma ), red drum ( Sciaenops ocellatus ), blue crab ( Callinectes sapidus ), brown shrimp ( Penaeus aztecus ), white shrimp ( Penaeus setiferus ), and oyster ( Crassostrea virginica ) (Halsted, 2003). In addition, many open water fish use these estuaries as nurseries for their young (U.S. Fish and Wildlife Service, 2005a ).

The MIMP is an important wintering ground for millions of migratory birds that use the central flyway each year (TNC, 2004). It is home to over 250 species of migratory and resident songbirds, shorebirds, waterfowl, and colonial waterbirds during some part of the year (TNC,

2004; Halsted, 2003). Since 1993, Mad Island has ranked among the top-five areas in the nation in number of species counted during the annual

Audubon Society’s Christmas Bird Count (Halsted,

2003).

Mad Island Bayou is a winding channel approximately 1,300 meters long that serves as the only tidal input for the approximately 400 acre Mad

Island Lake (USFWS, 2005b). Fresh water inputs to the lake include precipitation, runoff, and inflow from Mad Island Slough. Over the last 60 years, Figure 3. Close Up of the Oxbow Bend

4 urbanization, overgrazing, reduction of freshwater input and saltwater intrusion have combined to reduce the ecological diversity in the lake (Williams, 1993). TNC is concerned that increasing salinity will further disrupt the estuary’s ecosystem (TNC, 2001). One major point of concern is the imminent breaching of a large oxbow bend in the bayou (Fig. 3) that is threatening to decrease the length of the bayou by approximately 450 meters. If this breakthrough occurs, it may have adverse effects on this highly productive environment (USFWS, 2005b).

Figure 4. MIMP Study Area Divisions

This study focuses on the southwest shoreline of the MIMP from the western boundary fence to the sandy beach across from the break in the barrier islands (Fig. 4) . East of the opening between two of the dredge spoil barrier islands, the coastline is a combination of sandy beaches, riprap, concrete erosion control structures, and spartina marsh. Erosion in this area of the coastline will not affect the salinity of the Mad Island Lake. In addition, a cursory visit to the

5 area showed that the long-term erosion measurement stakes (installed by Williams, 1992) for this portion of coastline were destroyed, missing, or hidden by dense vegetation.

Previous Research and Ongoing Projects

Williams (1992) completed an erosion study at the MIMP funded by the Nature

Conservancy of Texas. Williams analyzed sequential aerial photographs dating from 1930,

1943, 1958, 1978, and 1991 to determine erosion rates along the MIMP’s shoreline for the previous 48 years. A secondary portion of the study included the establishment of a long term erosion monitoring program. A review of his study follows.

Williams mapped the edges of the erosional scarp/vegetation line from each year’s photo onto a single base map (scales adjusted to 1:8,000). The final base map showed a noticeable shift in the shoreline. Williams selected 26 points along the preserve boundary and measured erosion perpendicular to the shoreline (Williams, 1993b).

William’s measurement points (A, B, C, D, and E) shown in Figure 5 pertain to the study area for this project and are listed in Table 1. The data shows that the shoreline eroded an average of 47.2 meters (0.98 m/yr) from 1943 to 1991 resulting in approximately 0.074 km² of lost land area (Williams, 1991). In addition, Williams (1993b) found that the mouth of the bayou retreated by an estimated 50 meters during the same time period. In the vicinity of the oxbow bend section discussed earlier, Williams (1993b) estimated that the distance between the GIWW and the bayou was about 30 meters in 1991 and he predicted a breach within 24 years.

Figure 5. Williams' Base Map: Showing Letters Corresponding to

Measurement Locations and Erosion Measurement Stake Locations (Every Fifth Shown) (Adapted from Williams, 1992, 1993a, 1993b)

Table 1. Williams 48 year MIMP Erosion Measurements (Adapted from Williams, 1991) 1942-91 Erosion 1942–91 Erosion Rate Section m m/yr

A 57 1.19

B 56 1.17

C 43 0.9

D 29 0.61 E 51 1.06

7 In 1991, Williams installed a series of 93 stakes 30.48 m apart (except for three spaced

15.24 m apart along the area opposite of the barrier island opening) along the MIMP’s shoreline and measured the perpendicular distance from the shoreline to the stake. The stakes were 1.22 m lengths of 3/8 inch rebar which were driven approximately 0.61 m into the ground. Each stake had a tag number (1-93 sequentially from the west boundary fence to the east boundary fence) attached to it. For this study, stakes and data from numbers 1 - 38 ( Fig. 5 ) are within the study area and are listed in Appendix A.

One year later, Williams returned and re-measured the distances to determine the shoreline change over 1 year (Williams, 1993). For stakes 1-38 (Fig. 5) , changes ranged from 0 to 2.56 m/year with an average erosion rate of 0.75 m/year (Appendix A). The highest measurement was at stake #35 which is directly across from the break in the barrier islands (Fig.

5) . No measurements showed any accretion. For stake #14 (located at the aforementioned oxbow bend), Williams determined an erosion rate of 0.64 m/year. He estimated that this rate would cause a breach within about 10 years and revises his first study’s estimate of 24 years.

Twelve years later, the distance between the bend and the GIWW is about 3 meters, and after a period of heavy rainfall in the summer 2004, saltwater was observed flowing over the remaining land and into the bayou.

During initial field work in the summer 2004, only 7 stakes (1, 3, 8, 9, 10, 11, and 13) within the study area were located (2 additional stakes were found on the east portion of the preserve). The stakes were heavily corroded and several of the tags were missing. The tags that were attached with what appeared to be an aluminum wire were still in good shape, but the ones attached with steel wire were either missing or in poor condition. Neither Williams nor TNC completed further follow up studies to measure erosion rates and ensure the maintenance of the

8 stakes. Consequently, many stakes are now missing (presumably destroyed or hidden). Using a

30.48 m tape, stakes that were missing tags could be identified.

A project to stabilize the shoreline with an additional structure has been proposed and is awaiting funding. The proposed structure will tie into an existing concrete mat erosion control structure installed in 1996 and stretch approximately 244 m to the west ( Fig.6 ). The oxbow bend in the Mad Island Bayou is adjacent to this section of the shoreline. The design incorporates the

Reefblk™ erosion control system which uses a combination of reinforced iron stock and crushed oyster shell to construct an artificial reef which provides a site for oysters to colonize, further strengthening the structure and providing shoreline erosion protection (Coastal Environments,

Inc., Baton Rouge, Louisiana, www.coastalenv.com). Once established, TNC plans to create a spartina marsh along the shoreline. The Reefblk system may directly assist in protecting the

Mad Island Bayou by reducing the amount of wave energy that reaches the shoreline (Texas

Figure 6. Projected Location of the Reefblk Erosion Control Structure

9 CHAPTER 2

METHODOLOGY

Shoreline Delineation

The study area’s shoreline is divided into five classifications based on shoreline type

(Table 2, Fig. 4 ):

Table 2. Shoreline Description by Section Section Name Location Shoreline Type

Runs approximately 400 m Mud flats with spartina marshgrass 1. WEST Section E from the MIMP’s west extending into the water. boundary fence

Runs approximately 160 m Salt grass mud flats with an 2. WEST ESCARPMENT E from the end of the approximately 0.5 m cliff to the Section WEST Section waterline.

Runs approximately 120 m E from the end of the 3. CONCRETE MAT Interlocking concrete lattice erosion WEST ESCARPMENT Section control structure. Section to the mouth of Mad Island Bayou

Runs 200 m E from the Thick woody vegetation with an 4. CENTER Section mouth of Mad Island approximately 1.5 m cliff to the Bayou waterline.

Spans approximately 140 m from 30 m W to 30 m E 5. EAST Section Sandy beach of the break in the barrier islands

Spans approx. 60 m along Salt grass mud flats with an BAYOU BEND the S bank of the oxbow approximately 0.5 m cliff to the Subsection bend in Mad Island Bayou water line

10 1995 shoreline data comes from a corrected 1995 1 meter Digital Orthophoto Quarter

Quadrangle (DOQQ) (Universal Transverse Mercator (UTM), North American Datum (NAD)

83, Zone 14N) downloaded from the Texas Natural Resource Information System (TNRIS) and is the base map for this study. This image was chosen because it was the highest quality no-cost image available.

The shoreline for this study was defined as the erosional scarp. For the 400 m WEST

Section, the vegetation line was used because an erosional scarp does not exist. For approximately 99 percent of the study area, vegetation grows up to the water’s edge. The shoreline was defined in this manner because it is readily identifiable on air photographs and is consistent with Williams’ 1991 methods.

Data Preparation and Fieldwork

In February 2005, a sub-meter accuracy Trimble global positioning system (GPS) unit was used to map the Mad Island Marsh Preserve’s (MIMP) shoreline (data logged at 5 second intervals) three separate times. It was deemed appropriate to collect three shorelines to help evaluate the GPS error and the inherent error caused by walking in difficult terrain.

GPS data were downloaded and differentially corrected in Pathfinder

Office using base files from the Lake

Houston Base Station approximately

178 km away. The corrected data were Figure 7. Selected Section (WEST Section) of 2005 GPS Shorelines exported as shapefiles and projected into

11 UTM, NAD 83, Zone 14N to be consistent with the 1995 DOQQ base map.

The process of creating a single 2005 shoreline was based largely on the Digital

Shoreline Analysis System (available free from USGS) extension written for the ArcView® digital mapping system (Environmental Systems Research Institute, Redlands, CA, www.esri.com) (Theiler et al., 2003). The intent of this program is to measure historical shoreline changes by creating landward baselines and casting perpendicular transects to be used as measurement locations across multiple shorelines (Theiler et al., 2003). To create the average

2005 shoreline, the three GPS shoreline files ( Fig. 7 ) were added to the ArcMap® 9.0 digital mapping system (Environmental Systems Research Institute, Redlands, CA, www.esri.com). All three shoreline files were selected and a 3 meter buffer was created around the lines, resulting in a single buffer 3 meters around the outer most line. This buffer was added to ArcView 3.3.

Using the Digital Shoreline Analysis System extension for ArcView, the buffer was converted to a polyline and the line was split on the top left and top right directly above the end of the

Figure 8. Selected Section (CENTER Section) Showing 2005 Baseline (top) GPS Shorelines (Bottom 3) and Transects (Numbered Lines)

12 shorelines. The bottom and side sections of the buffer were deleted resulting in a single line 3 meters from the 2005 GPS shorelines that represents the general shape of the 2005 shoreline

(Fig. 8 ).

The 2005 baseline was added to ArcMap 9.0, divided at 5 meter intervals (divide line tool), values calculated for the Id field ( Id=FID + 1), and the symbology of the baseline was changed so that each 5 meter line segment was discernable. The transect lines were manually created by snapping to the beginning of each 5 meter segment and drawing a line perpendicular

(perpendicular line tool) to the baseline and down across all three 2005 GPS shorelines ( Fig. 8 ).

Once the two hundred and thirteen transect lines were created, a new polyline file was made. For each transect, the line was zoomed into and a new line was snapped to the upper most shoreline, drawn down tracing the transect line, and snapped to the bottom most shoreline.

After repeating the process for Figure 9. Selected Section (CENTER Section) Zoomed in all transects, the new file to Demonstrate Separation Between 2005 GPS Shorelines contained the distance across the three 2005 GPS shorelines at each transect ( Fig. 9 ). Using the calculate length command, the length of each segment was added to the data base table. The average distance across the three

2005 GPS shorelines was 0.69 m ( Appendix B).

Because the average separation between the three shorelines was less than a meter, it was deemed adequate to create the 2005 average shoreline visually. Beginning at transect one, a

13 polyline vertex was placed along each transect at the estimated average distance between the three 2005 GPS shorelines. The end result was a single average 2005 shoreline created by connecting the two-hundred and thirteen transect lines ( Fig. 10 ).

Figure 10. Selected Section (CONCRETE MAT Section) Zoomed in to Demonstrate Creation of Average 2005 Shoreline. Red Line Represents the Average 2005 Shoreline

The 1995 shoreline was created from the one-meter resolution 1995 DOQQ downloaded from TNRIS. The 1995 DOQQ presented an unanticipated problem. At some locations, the shoreline was difficult to identify at a large scale due to the subtle color changes in the pixels; whereas, at smaller scales, the shoreline was more distinct. The following method was used to create a single shoreline and to provide assessment of the error associated with drawing the shoreline visually. Three separate 1995 shorelines were drawn at the following scales: 1:500

(large visible pixels), 1:1,000 (medium visible pixels), and 1:1,500 (small visible pixels). Two- hundred and sixteen five-meter transects were created using the same methods as the 2005 shorelines and the average distance between the shorelines was found to be 0.97 m ( Appendix

14 D). A single polyline representing the 1995 shoreline was created from the three shorelines by the same methods as the 2005 shoreline.

Error

For each of Williams’ remaining stakes, a GPS point was recorded, the perpendicular distance from the stake to the shoreline was measured with a 30m tape ( Fig. 11 ), and the shoreline position was recorded with a GPS point. For GPS point data, 20 GPS readings were collected at 5 second intervals and automatically averaged by the GPS equipment into one point.

The tape measure was also used to measure the distances between Williams’ stakes. The GPS points were added to ArcMap, polylines were created, and lengths were calculated to measure the same distances tape measured in the field ( Fig. 12 ). Table 3 was created and the root mean square error (RMSE: ±0.14m) was calculated to determine the difference between the tape measurements and the ArcMap measurements.

Figure 11. Photograph of Williams’ Erosion Monitoring Stake

15 Figure 12. Selected Section of Williams Stakes Demonstrating ArcMap Measurement Distances (m)

Table 3. RMSE Between ArcMap Measurements and Tape Measurements

A B C D Stakes Tape Measurement ArcMap Measurement A - B C² m m m m 1 20.0 20.1 -0.01 0.00 1 to 3 62.0 62.2 -0.14 0.02 3 14.9 15.1 -0.20 0.04 8 22.1 22.1 -0.03 0.00 9 21.6 21.7 -0.09 0.01 10 19.9 19.8 0.11 0.01 11 18.2 18.3 -0.04 0.00 13 5.4 5.3 0.04 0.00 8 to 9 30.4 30.5 -0.19 0.04 9 to 10 30.7 30.7 -0.02 0.00 10 to 11 30.4 30.2 0.18 0.03 11 to 13 60.9 60.5 0.32 0.10

D = Mean of C² 0.02 Sqrt. D 0.14

RMSE ±0.14m

Figure 13. GCP at the MIMP Office Figure 14. GCPs at Selected MIMP Building Road Intersections

Ground control GPS points (GCP) were taken at eleven road intersections throughout the

MIMP. The road intersections at the Mad Island Marsh Preserve are sweeping turns; not 90° intersections. Therefore, ground control points were collected at the visually estimated apex of each turn. When the GCPs were added to the 1995 DOQQ, they appeared to be in the correct location. However, because the “on-the-ground” location had to be visually estimated, it was impossible to estimate the actual error ( Fig. 14 ).

One GCP was collected at the NW corner of the Nature Conservancy of Texas’ (TNC) office building ( Fig. 13 ), and two GCPs were collected at the NW and SW corners of the barn.

For the corner of the TNC office building, the GCP was within the correct pixel on the DOQQ suggesting an error of no greater than 1m. For the barn, both GCPs appeared to be in the correct pixels; however, there was less contrast between the building and the ground (compared to the

TNC office building), resulting in greater uncertainty in identifying pixels representing the corners of the building.

17 Because the quantifiable error estimations were less than 1m, the GPS equipment is rated sub-meter accuracy, and the GCPs appeared to be in the correct pixels on the DOQQ, the positional error for this project was estimated at ±1.0 m. The points defining each end of a line have an error of ±1.0 m; this translates to an error of ±2.0 m for distances derived from GPS positions.

Data Analysis

The averaged 1995 and 2005 GPS derived shorelines were added to ArcMap and a baseline and 10 meter transect lines (resulting in 110 transect lines) were generated using the method described for the 1995 and 2005 shorelines. A new polyline shapefile was created by snapping lines between the 1995 and 2005 shorelines along the 10 m transects. The calculate values command was used to measure the amount of erosion/accretion between the two shorelines along each transect. The data base file was exported to spreadsheet software and areas of erosion were given negative values ( Appendix D).

To determine the total area of lost land, two polygon files were created. The first encompass areas of erosion and the second encompasses areas of accretion between the 1995 and

2005 shoreline ( Fig. 15 ). The calculate area tool was used to determine the total m² of net lost land area.

Figure 15. Selected Section (WEST Section) Showing Polygons Created Between the 1995 and 2005 Shorelines

18 CHAPTER 3

RESULTS

Overview

Table 4 shows that the average erosion rate for the entire study area was calculated to be

0.23 m/yr (including the ±0.2 m/yr error: -0.03 to -0.43 m/yr). Of the 110 measurement locations ( Appendix D), 78 showed erosion and 22 showed accretion (range +6.37 m to -11.61 m). Rate comparisons are shown in Table 4. Because of the varying shoreline types, it is more relevant to study the results on a per-section basis. Land loss calculations ( Table 5 ) show that

2,997 m² of land eroded and 518 m² accreted, resulting in a total net loss of 2,479 m² of land

(error factor not included in these calculations).

Table 4. MIMP Erosion Rates by Section and Rate Comparisons with two

Previous Studies 1943-91¹ 1992-93² 1995-05 Section m/yr m/yr m/yr ENTIRE STUDY AREA Stakes 1 -- 110 -0.99 -0.75 -0.23 ±0.2m WEST Section Stakes 1 -- 43 -1.18 -0.69 -0.22 ±0.2m WEST ESCARPMENT Sec. Stakes 44 -- 61 -1.04³ -1.26 -0.69 ±0.2m CONCRETE MAT Section Stakes 62 -- 74 -0.9 -0.82 +0.08 ±0.2m CENTER Section Stakes 75 -- 96 -0.61 -0.45 -0.01 ±0.2m EAST Section Stakes 97 -- 110 -1.06 -0.88 -0.33 ±0.2m BAYOU BEND Subsectionª Stakes B1 – B8 NO DATA NO DATA -0.37 ±0.2m

¹ Williams, 1992 ² Williams, 1993a; Williams, 1993b ³ Average of Williams (1993b) Section B and C ª Considered a sub-section: methods slightly different.

Table 5. Land loss calculations (Error not Included)

Accreted 1995-2005 Eroded 1995-2005

Id Polygon Area Id Polygon Area 1 0.11 sq. m 1 0.10 sq. m 2 5.64 sq. m 2 51.08 sq. m 3 29.47 sq. m 3 303.82 sq. m 4 1.34 sq. m 4 262.77 sq. m 5 0.21 sq. m 5 19.59 sq. m 6 0.57 sq. m 6 400.99 sq. m 7 104.34 sq. m 7 16.02 sq. m 8 105.94 sq. m 8 22.94 sq. m 9 77.29 sq. m 9 1200.56 sq. m 10 1.40 sq. m 10 221.68 sq. m 11 142.09 sq. m 11 64.36 sq. m 12 49.75 sq. m 12 8.46 sq. m 13 424.82 sq. m

Accreted 518.15 sq. m Eroded 2997.19 sq. m

Eroded 2997.19 sq. m Accreted 518.15 sq. m

Net Land Loss 2479.04 sq. m

WEST Section

The erosion rate for the WEST Section ( Fig. 16, Table 4 ) was calculated at -0.22 m/yr

(including the ±0.2 m/yr error: -0.02 to -0.42 m/yr) and showed the third highest rate of erosion

(95-05). It appears that the WEST Section’s shoreline type has changed over the last decade.

For Williams’ 1993 study, approximately 70% the shoreline was identified as cliff (Williams,

1993a, 1993b). During field work in 2005, the shoreline was gradually sloping with spartina marsh along the land water interface ( Fig. 17 ). The reason(s) for this change are unknown; it is possible that the installation of the concrete mat to the east affected erosional processes on this section of shoreline.

Figure 16. WEST Section with 1995 and 2005 Shorelines

Figure 17. WEST Section Photograph

21 WEST ESCARPMENT Section

The erosion rate for the WEST ESCARPMENT Section ( Fig. 18, Table 4 ) was calculated at -0.69 m/yr (including the ±0.2 m/yr error: -0.49 to -0.89 m/yr). Of the 18 measurement locations, 17 showed erosion and 1 showed accretion (range: +0.41 to -1.16 m/yr).

This section showed the highest erosion rate; more than double that of any other section.

The WEST ESCARPMENT Section begins approximately 25 meters to the east of the center of the oxbow bend in Mad Island Bayou and the shoreline in this location is a small

(approximately 0.5 m) cliff with vegetation extending to the cliff’s edge. The majority of the root mass is well above the water line and waves strike bare sediment ( Fig. 19 ).

Figure 18. WEST ESCARPMENT Section with 1995 and 2005 Shorelines

Figure 19. WEST ESCARPMENT Section photograph

CONCRETE MAT Section

The accretion/erosion rate for the CONCRETE MAT Section ( Fig. 20, Table 4 ) was calculated at +0.08 m/yr (including the ±0.2 m/yr error: +0.28 to -0.12 m/yr) which is within the

±0.2 m/yr error. Of the 13 measurement locations, 1 showed erosion and 12 showed accretion

(range: 0.18 to -0.13 m/yr). The results from this section are misleading. In 1996, after the capture of the 1995 DOQQ image, an interlocking lattice of concrete blocks ( Fig. 21 ) was installed as an erosion control barrier. It would appear from the data that the mat is working; however, several failures were observed in the mat. One section of the mat, approximately 10 meters in length, has collapsed ( Fig. 22 ) and saltwater was observed freely flowing over the top of the mat into the bayou in the summer 2004. In addition, several sections of the mat were only held up because of the arched shape of the mat. Underneath, the mat is hollow and saltwater

23 moves freely between the Gulf Intracoastal Water Way (GIWW) and Mad Island Bayou. It appears that the concrete mat, although still “in place,” has failed to stem erosion.

Figure 20. CONCRETE MAT Section with 1995 and 2005 Shorelines

Figure 21. CONCRETE MAT Section Figure 22. CONCRETE MAT Section Photograph Failure Photograph

24 CENTER Section

The erosion rate for the Center Section ( Fig. 23, Table 4 ) was calculated at -0.01 m/yr

(including the ±0.2 m/yr error: +0.19 to -0.21 m/yr) and is within the ±0.2 m/yr error. Of the 22 measurement locations, 14 showed erosion and 8 showed accretion (range: +0.6 to -0.45 m/yr).

The shoreline consists of a cliff (approximately 1.5 m) with dense hardwood and grassy vegetation extending up to and along the cliff face. It appears that the dense root mat ( Fig. 24 ) along the shoreline reduces wave erosion.

Figure 23. CENTER Section with 1995 and 2005 Shorelines

Figure 24. Center Section Photograph

EAST Section

The erosion rate for the EAST Section ( Fig. 28, Table 4 ) was calculated at -0.3 m/yr

(including the ±0.2 m/yr error: -0.1 to -0.5 m/yr) and showed the second highest rate of erosion

(excluding the Oxbow Bend Subsection). Of the 14 measurement locations, 11 showed erosion and 3 showed accretion (range: +0.24 to -0.75 m/yr). It appears that the lack of vegetation in this location ( Fig. 26 ) has contributed to a higher erosion rate than most of the vegetated sections. It was anticipated that this section would show the highest erosion rate because it is not protected by the barrier islands and is subject to both wave attack from the Matagorda Bay and from barge traffic in the GIWW. Data shows that this hypothesis was incorrect.

Figure 25. EAST Section with 1995 and 2005 Shorelines

Figure 26. East Section Photograph

27 BAYOU BEND Subsection

Because it was intended to serve only as a visual reference, only a single 2005 GPS polyline, instead of three, was recorded for the south bank of the oxbow bend in the Mad Island

Bayou. Unlike the remainder of the study area, this single GPS line serves as the 2005 shoreline of the bayou. This line was taken during the same time frame with the same equipment as the shoreline of the GIWW, so the error is assumed to be the same ± 0.2 m/yr. The creation of the

1995 shoreline, transects, and erosion distance measurements were completed using the same processes listed previously.

The erosion rate for the BAYOU BEND Subsection ( Fig. 27, Table 4 ) was calculated at

-0.37 m/yr (including the ±0.2 m/yr error: -0.17 to -0.57 m/yr) and showed the second highest rate of erosion. Of the 8 measurement locations, all showed erosion (range: -2.91 to -4.41 m).

Figure 27. BAYOU BEND Subsection with 1995 and 2005

Shorelines

28 CHAPTER 5

DISCUSSION

Entire Study Area

Of the five sections, three (WEST, WEST ESCARPMENT, and EAST) showed that erosion was occurring along the Mad Island Marsh Preserve’s (MIMP) shoreline and two sections (CONCRETE MAT and CENTER) were within the ±0.2 m/yr error ( Fig. 28 ).

However, field observations suggest that the results from the CONCRETE MAT Section are erroneous because portions of the land under the mat have been eroded away.

0.2 ENTIRE STUDY WEST WEST ESC. CONCRETE MAT CENTER EAST Area Section Section Section Section Section 0

-0.2

-0.4

-0.6 m/yr

-0.8

-1

1943-1991 1992-1993 1995-2005

-1.2

1) All 95-05 data should be considered with a +/- 0.2 m/yr error -1.4 Figure 28. MIMP Erosion Rate Graph: Comparison Across Three Studies ¹1943 – 1991 Data (Williams, 1991) ²1992 – 1993 Data (Williams, 1993) ³ 1995 – 2005 Data Error = ± 0.2 m

The data suggests that shoreline erosion rates may be more influenced by shoreline type than protection from the forces of wave attack. Although it receives protection from the barrier islands, the WEST ESCARPMENT Section’s (approx. 0.5 m cliff) erosion rate was more than

29 double that of the EAST Section (sandy beach) which is open to additional wave attack from the

Matagorda Bay.

Studies have suggested that 10 years is the minimum timeframe for erosion studies to accurately portray long term trends (Gibeault, 2003), providing environmental conditions remain constant. Including the ±0.2 m/yr error, results from this study showed that current erosion rates for 1995 to 2005 are much less that both of Williams’ previous studies ( Fig. 28 ). The discrepancy between the studies could be due a change in conditions. For example, a dense root mat that was absent from the 1940’s through 1980’s may currently protect the Center Section. In addition, the development of spartina marsh throughout the last decade along the WEST Section may have been a factor in the decreased erosion rates. This study may be useful for predicting future shoreline erosion rates if environmental conditions remain relatively constant.

It was assumed that the major threat to the oxbow bend in Mad Island Bayou was from erosion along the WEST Section. However, the imminent breakthrough may also result from erosion of the south bank of Mad Island Bayou. Interviews with TNC personnel revealed that a sign post along this section recently washed away into the bayou. Erosion along the south bank of the bayou may be caused by boat traffic from commercial crab boats and sport fishers in the bayou, the diurnal tidal in/out flow, and the physical processes of water speeding up along the outer edge of a bend.

Based on 1995 to 2005 erosion rate calculations, the oxbow bend in Mad Island Bayou will breach in approximately ten years. At the apex of the bend, measurements showed that spartina marsh is currently growing. The break through is likely to occur about 10 m west of the apex of the bayou bend where the GIWW shoreline and the Mad Island Bayou are both eroding.

However, it is important to note that, after a period of heavy rainfall in the summer of 2004,

30 saltwater was observed flowing over the center of the oxbow bend and into the bayou.

Therefore, it is possible that the bayou could breach sooner.

Recommendations

1. The Army Corps of Engineers (USACE) is tasked with maintaining the GIWW and part

of the process includes regular dredging of the channel. The USACE dumps the spoils to

the south, which replenishes the shoreline of the barrier islands. The USACE should

consider dumping the spoils to the north thereby adding landmass to the MIMP’s

shoreline.

2. TNC should reconsider the

location of the Reefblk™

erosion control system project

(Coastal Environments, Inc.,

Baton Rouge, Louisiana,

www.coastalenv.com) .

Fieldwork showed that the

concrete mat has not stopped

erosion along the mouth of Mad

Island Bayou. TNC could install Figure 29. Recommended Changes to the the Reefblk along the Bayou Bend Section

CONCRETE MAT Section and alter the shape of the oxbow bend. For example, the

oxbow bend could be cut short and that sediment could be used to fill in the bayou along

the oxbow bend resulting in a shorter bend that is protected by more land mass.

31 3. TNC should determine the usefulness of the road along the EAST Section. If deemed

un-important, financial resources should be allocated to combat erosion elsewhere. As

erosion continues along the EAST Section, the shoreline will reach the densely vegetated

north side of the road. This will create a “shoreline type” similar to the Center Section

which showed erosion rates within the margin of error.

4. TNC should use the GIS data from this study to monitor erosion rates at yearly intervals.

With limited effort, GIS data could be collected and analyzed following the same

methods of this project. The transects and baseline data provided by this study could be

used as template to make future studies user-friendly and field work and GIS mapping

could be completed in less than a day. In addition, measurements will be compared at

the exact same locations, which should give TNC managers reliable data with which to

make management decisions.

Discussion of Methods

The methodology used by this study could be used at various scales and may be relevant for other coastal areas and other water body types (e.g. lakes, reservoirs, rivers, and etcetera). In addition, it may provide a cost effective alternative to smaller municipalities who lack funding for more large scale and expensive measurement techniques like light detection and ranging

(LIDAR) mapping. With limited resources, cities could establish long-term erosion monitoring projects that are easily repeatable.

The methods may also be useful for monitoring single, large-scale event situations. For example, a shoreline damage assessment could be done immediately following hurricane and tropical storm weather events. Or, cities could use the data to determine changes in rivers and streams following large scale construction projects in the area. As stated earlier, one benefit of

32 this methodology is that it allows for measurement comparisons at the same locations. Also, because transects are the same year to year, follow up study can be completed regardless of personnel changes.

The lack of ground control points (GCPs) in rural locations should be addressed. Within a city, ground control points like road intersections and buildings are easily determined and utilized. In rural areas, there may be no readily identifiable GCPs within a study area. On a statewide scale, decision makers should consider installing on-the-ground objects in rural locations that can be seen from aerial photography. On a smaller scale, organizations or a small municipalities could install a series of GCPs throughout their purview so that air photographs can be quickly and accurately georeferenced. It is essential that the GCPs be made of a sturdy material, be larger than on meter, and be visible from the air.

Recommendations for Further Research

There is a need for two additional studies to be completed at Mad Island Lake.

Primarily, geographic information systems (GIS) technology could be used to model the outcome of increased salinity in Mad Island Lake. The study should focus on how much salt the ecosystem can handle before adverse affects are realized. For example, there should be a threshold salinity established and the lake should be monitored so that increases will be recognized prior to reaching levels that result in major ecosystem change. Secondarily, GIS could be used to model salinity levels based on the length of the Mad Island Bayou. For instance, how much will the salinity of the lake increase with the loss of 100, 200, 300… meters of bayou? Both of these studies could make excellent dissertation or thesis projects for a combination of geographers, biologists, chemists, or environmental scientists.

APPENDIX A

WILLIAMS’ ONE-YEAR MONITORING PROGRAM STAKE MEASUREMENTS

Adapted from Williams, 1993.

Distance to Distance to Shoreline Stake Shoreline 6/9/92 Shoreline 5/22/93 Migration Number meters meters m/year 1 23.90 23.07 0.85 2 20.91 20.30 0.64 3 20.33 19.63 0.73 4 18.71 18.11 0.64 5 17.37 16.22 1.22 6 25.88 25.45 0.46 7 24.99 23.99 1.07 8 24.38 23.68 0.73 9 25.45 24.81 0.67 10 28.04 27.89 0.15 11 24.38 23.77 0.64 12 11.83 11.43 0.43 13 5.79 5.24 0.58 14 5.03 4.42 0.64 15 10.42 9.54 0.94 16 10.06 9.27 0.82 17 12.71 10.76 2.04 18 14.26 13.11 1.22 19 11.77 10.85 0.98 20 5.33 4.69 0.67 21 4.88 3.54 1.40 22 2.68 2.10 0.61 23 3.54 2.96 0.61 24 5.33 5.30 0.03 25 2.35 2.32 0.03 26 2.62 2.59 0.03 27 4.27 4.24 0.03 28 1.52 1.52 0.00 29 2.83 1.52 1.37 30 5.55 4.05 1.58 31 5.64 5.15 0.52 32 6.40 6.19 0.21 33 6.55 6.40 0.15 34 11.19 10.06 1.19 35 5.88 3.44 2.56 36 9.75 8.11 1.74 37 11.58 11.28 0.34 38 11.73 11.73 0.00

Average Study Area Erosion Rate 0.75 m/yr

APPENDIX B

2005 GPS SHORELINE CREATION ERROR MEASUREMENTS

Transect Length 56 1.356 113 0.474 170 1.018 Number (m) 57 0.743 114 0.304 171 0.379 1 0.349 58 1.615 115 0.313 172 0.209 2 0.064 59 1.504 116 0.328 173 0.232 3 0.206 60 1.346 117 0.528 174 0.805 4 0.289 61 0.753 118 0.196 175 0.270 5 0.207 62 0.391 119 0.786 176 0.451 6 0.143 63 0.699 120 0.572 177 0.380 7 0.275 64 1.140 121 1.046 178 0.582 8 0.456 65 0.399 122 1.018 179 0.304 9 0.139 66 0.592 123 1.085 180 0.063 10 0.248 67 0.772 124 0.877 181 0.171 11 0.505 68 0.981 125 0.866 182 0.862 12 0.094 69 1.442 126 0.869 183 0.417 13 0.326 70 1.605 127 0.461 184 1.455 14 0.611 71 1.891 128 0.836 185 0.989 15 1.444 72 1.740 129 0.900 186 0.268 16 4.324 73 1.564 130 0.607 187 0.159 17 3.074 74 0.783 131 0.897 188 0.383 18 1.033 75 0.944 132 0.845 189 0.284 19 3.816 76 1.124 133 0.590 190 0.274 20 3.929 77 1.058 134 0.294 191 0.258 21 3.037 78 0.775 135 0.592 192 0.271 22 0.472 79 1.009 136 0.322 193 0.259 23 1.778 80 1.301 137 0.532 194 0.408 24 1.604 81 1.310 138 0.628 195 1.765 25 0.635 82 0.373 139 0.924 196 0.206 26 0.564 83 1.025 140 0.623 197 0.192 27 0.525 84 1.021 141 0.629 198 0.325 28 0.529 85 1.263 142 0.603 199 0.155 29 0.662 86 0.710 143 0.186 200 0.162 30 0.445 87 0.586 144 0.086 201 0.050 31 0.222 88 0.460 145 0.477 202 0.381 32 0.730 89 0.347 146 0.620 203 0.355 33 0.346 90 0.231 147 0.283 204 0.673 34 0.083 91 0.168 148 0.460 205 0.405 35 0.283 92 0.385 149 1.335 206 0.390 36 0.182 93 0.456 150 0.054 207 0.215 37 0.099 94 0.225 151 0.134 208 1.779 38 0.167 95 0.316 152 0.220 209 0.450 39 0.107 96 0.245 153 0.291 210 0.504 40 0.256 97 0.183 154 0.447 211 0.346 41 0.607 98 0.677 155 0.083 212 0.530 42 0.877 99 0.427 156 0.892 213 0.362 43 0.531 100 0.530 157 0.405 44 0.143 101 0.589 158 0.311 45 0.260 102 0.509 159 0.214 46 0.792 103 0.497 160 0.403 47 0.574 104 0.339 161 0.116 48 2.597 105 0.393 162 0.341 49 2.844 106 0.279 163 0.090 50 1.904 107 0.328 164 0.753 51 1.416 108 0.753 165 0.623 52 0.909 109 0.708 166 0.972 53 1.753 110 0.548 167 0.202 54 0.620 111 0.538 168 0.302 55 0.190 112 0.652 169 0.463

APENDIX C

1995 SHORELINE CREATION ERROR ESTIMANTS

Transect 65 1.151 131 0.451 197 1.317 Number Length 66 1.172 132 1.159 198 0.438 1 1.087 67 1.050 133 1.116 199 0.772 2 0.414 68 0.925 134 1.445 200 0.525 3 0.239 69 0.717 135 2.042 201 0.878 4 1.531 70 0.840 136 1.428 202 0.958 5 1.675 71 0.464 137 0.816 203 0.524 6 2.431 72 0.460 138 1.614 204 0.985 7 0.913 73 1.013 139 0.751 205 0.991 8 0.633 74 2.517 140 0.771 206 0.417 9 0.806 75 1.821 141 1.345 207 0.122 10 0.629 76 1.670 142 1.083 208 0.773 11 0.507 77 1.152 143 1.395 209 0.657 12 0.136 78 0.428 144 0.811 210 0.562 13 0.483 79 0.954 145 1.229 211 0.479 14 0.772 80 1.040 146 1.431 212 0.618 15 1.314 81 0.530 147 0.654 213 0.561 16 0.361 82 0.758 148 0.804 214 0.489 17 0.232 83 1.549 149 0.392 215 0.645 18 0.475 84 1.112 150 0.902 216 0.700 19 0.483 85 0.898 151 1.507 20 0.722 86 0.617 152 1.229 21 0.429 87 1.992 153 1.201 22 0.302 88 1.238 154 0.796 23 0.745 89 0.868 155 1.578 24 0.728 90 0.721 156 1.162 25 1.106 91 1.277 157 0.711 26 0.668 92 0.911 158 1.152 27 0.640 93 0.627 159 0.662 28 1.243 94 0.650 160 0.653 29 0.824 95 0.855 161 1.150 30 0.334 96 0.739 162 1.244 31 0.720 97 0.687 163 1.507 32 0.580 98 0.921 164 1.128 33 0.776 99 1.430 165 0.785 34 0.584 100 0.983 166 0.864 35 1.407 101 1.038 167 1.092 36 0.603 102 1.120 168 1.055 37 1.113 103 0.961 169 1.170 38 1.091 104 0.629 170 1.481 39 0.982 105 0.922 171 1.233 40 0.648 106 0.913 172 1.998 41 1.165 107 3.055 173 0.469 42 1.200 108 2.472 174 0.598 43 0.858 109 1.062 175 1.204 44 0.259 110 1.584 176 0.694 45 0.521 111 1.327 177 0.592 46 0.328 112 1.025 178 0.111 47 0.846 113 0.808 179 0.591 48 1.103 114 0.871 180 0.709 49 1.223 115 1.017 181 1.189 50 0.905 116 0.598 182 1.160 51 1.716 117 0.728 183 1.159 52 1.566 118 0.988 184 1.542 53 1.002 119 1.097 185 0.372 54 0.544 120 1.301 186 0.466 55 2.554 121 1.155 187 0.211 56 1.004 122 1.438 188 1.002 57 0.906 123 0.863 189 1.993 58 0.856 124 0.986 190 0.996 59 0.421 125 0.988 191 0.719 60 0.775 126 0.642 192 1.107 61 0.859 127 1.394 193 0.458 62 1.206 128 2.554 194 0.515 63 0.940 129 3.314 195 0.549 64 1.092 130 0.908 196 1.207

APENDIX D

DIFFERENCE BETWEEN 1995 AND 2005 SHORELINES. AREAS OF EROSION ARE

NEGATIVE VALUES ERROR ±0.2 m

Entire Study Length 47 -5.625 95 5.136 Area Dif. 48 -6.393 96 2.566 Transect Number 95 -- 05 49 -6.914 97 -1.792 1 -0.089 50 -7.665 98 -5.457 2 -2.602 51 -9.581 99 -5.890 3 -0.813 52 -10.189 100 -7.015 4 -1.375 53 -11.612 101 -7.472 5 -0.309 54 -11.380 102 -7.362 6 0.943 55 -10.322 103 -6.820 7 -3.468 56 -10.112 104 -3.867 8 -7.244 57 -7.788 105 -2.318 9 -4.529 58 -7.916 106 2.465 10 -4.495 59 -7.959 107 1.930 11 -6.769 60 -4.628 108 0.363 12 -4.117 61 -3.610 109 -1.489 13 -1.905 62 -1.314 110 -1.378 14 -0.606 63 1.776 15 1.561 64 1.659 16 2.036 65 0.667 17 -2.290 66 1.142 18 -3.282 67 1.750 19 -0.339 68 1.454 20 -3.551 69 0.426 21 -6.946 70 1.099 22 -4.451 71 0.026 23 -1.986 72 0.504 24 -4.190 73 0.605 25 0.344 74 0.643 26 -0.732 75 6.368 27 -1.696 76 4.519 28 -4.577 77 2.125 29 -5.474 78 -1.562 30 -4.651 79 -2.671 31 -4.219 80 -2.688 32 -5.715 81 -3.400 33 -5.278 82 -4.473 34 -5.192 83 -3.166 35 -5.258 84 -3.026 36 -0.988 85 -3.043 37 -1.519 86 -0.727 38 -0.176 87 -0.850 39 -1.992 88 -1.645 40 3.636 89 -2.105 41 3.677 90 -1.820 42 3.516 91 -1.143 43 4.014 92 2.565 44 4.127 93 2.816 45 -1.875 94 4.677 46 -4.254

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