Clearing the Mississippi Coast, Locating Post Hurricane Katrina Marine Debris

Transcription

1 Joseph Burke (primary author and intended presenter) Project Manager NOAA Division, C&C Technologies, Inc. 730 East Kaliste Saloom Rd., Lafayette LA, USA Phone: , Scott Croft Manager NOAA Division, C&C Technologies, Inc. 730 East Kaliste Saloom Rd., Lafayette LA, USA Phone: , ABSTRACT: As part of a comprehensive coastal debris-mapping project, C&C Technologies Inc. has teamed with the Mississippi Department of Marine Resources, NOAA, and FEMA in an unprecedented hurricane response survey following the devastation of Hurricane Katrina. C&C Technologies Inc. is tasked with mapping the entire coastal zone of Mississippi, extending out one and a half miles into the Mississippi Sound. In order to efficiently collect this data, C&C Technologies deployed multiple small boats throughout the survey area. As of December 2006, survey efforts have been completed from Waveland MS to Belle Fontaine Point MS, and 1,345 contacts have been marked. The contact s positions have been submitted to NOAA for immediate release to local interests. Upon the completion of the survey in the spring of 2007, approximately 4,017 linear nautical miles of side scan sonar and single beam echosounder data will have been collected, covering a total of 114 square nautical miles. In addition to providing the positions of a large number of nautical hazards, the data collected during this survey will be used to update the local nautical charts, which in many cases rely upon soundings several decades old. 1

2 TABLE OF CONTENTS INTRODUCTION... 3 AREA SURVEYED... 3 TEST AREAS... 3 OPR-J977-KR-CC... 4 EQUIPMENT... 7 SURVEY VESSELS... 7 SINGLE BEAM SONAR OPERATIONS... 9 SIDE SCAN SONAR OPERATIONS QUALITY CONTROL SINGLE BEAM SIDE SCAN REVIEW PROCESS CONTACT SELECTION CORRECTIONS TO ECHO SOUNDINGS VESSEL CONFIGURATION CORRECTIONS STATIC AND DYNAMIC DRAFT CORRECTIONS VESSEL MOTION CORRECTIONS SOUND VELOCITY CORRECTIONS VERTICAL AND HORIZONTAL CONTROL RESULTS CONTACTS INVESTIGATIONS AIDS TO NAVIGATION GRAB SAMPLES CHART COMPARISONS DATA SUBMISSION INTERIM DELIVERABLES CONTACT SPREADSHEETS CONTACT IMAGES MOSAICS FINAL DELIVERABLES CONCLUSION

3 INTRODUCTION Hurricane Katrina made landfall near Bay St. Louis, Mississippi on August 28, 2005, preceded by a storm surge of up to 28 feet. In addition to a massive storm surge, the coast and all its infrastructure was subjected to damaging hurricane force winds for approximately seventeen hours. After the skies settled, floods receded, and people began to slowly but surely return to where their homes and businesses had previously existed, photographs of the bits and pieces that remained of coastal towns were quickly spread on the Internet providing a testament to the overwhelming power of a monstrous storm. The damage that could not be captured in those photographs, however, was the amount of debris and trash that was left lying submerged on the bottom of the Mississippi Sound. Following the storm, NOAA, FEMA, and the Mississippi Department of Natural Resources tasked C&C Technologies to conduct four test area surveys along the coast of Mississippi. The data collected in the test areas clearly showed that there was a large amount of debris that had been washed from the coast into the Mississippi Sound, becoming a serious threat to both commercial and recreational boaters. As a result, C&C Technologies was then asked to plan and carry out an extensive survey of the entire Mississippi Coast. This second, larger survey was assigned a NOAA project number, OPR-J977-KR-CC, and the six surveys within the project were assigned unique H-numbers. Over 1,300 contacts were identified during this survey, and their locations were rapidly distributed to local entities through NOAA. In addition to quickly providing local boaters with information about hurricane debris, the results of this survey will also be used to update the local nautical charts. AREA SURVEYED TEST AREAS Four test areas were created and assigned by NOAA after consultation with the Mississippi Department of Marine Resources. The four areas were located such that they could provide a representative sample of how much and what type of debris was present within the sound. 3

4 C & C received the official statement of work and request to proceed on May 10, Survey operations were started in area 4, near Pascagoula, on May 14. Operations began in Pascagoula because there was still a significant lack of infrastructure and facilities available in the western half of the state. Upon completion of an area, we moved west to the next area. Area 3 lay outside of Biloxi, and area 2 was outside of Gulfport. The final area surveyed, area 1 south of Bay St. Louis, was completed on August 7. Much of survey area 4 near Pascagoula was very shallow water. In the northeast portion of the survey area, we were asked to survey within a charted breakwater, where the only available information concerning the water depth is a note on the chart reading Shoaling In addition, there were several instances where the charted depth is 2-3 feet. Because of the shallow depths we chose to utilize the Arlen, a shallow water vessel that drafts less than 2 feet. Area 3, south of Biloxi, was run second. The eastern section of this survey, near Deer Island, is also very shallow. We continued to use the Arlen until the shallow sections had been collected, at which point we switched vessels and began surveying aboard the Hydro Surveyor. The majority of areas 2 and 1, south of Gulfport and Bay St. Louis respectively, was deeper than 6 feet and surveyed with the Hydro. OPR-J977-KR-CC Following the completion of the four test areas, NOAA requested that C & C plan and carry out an additional survey along the entire length of Mississippi, from Louisiana to Alabama, and consisting of five separate H-number surveys. A sixth H-number survey was added to the overall survey area midway through the project. The first five areas were named consecutively from H11616 H The sixth area was named H The final statement of work and request to proceed was received on September 11. C & C arrived on site in Biloxi on September 12, and began working on September 13. 4

5 H11616 Sheet A H11616 is the western-most sheet of the survey, covering the area between Clermont Harbor and Grand Island. The water depths in this survey area are relatively deep, allowing for the entire area to be run by a single vessel, the High Roller. H11617 Sheet B H11617 is located between Waveland Pass and Pass Christian. This area includes Bay St. Louis, and contained the greatest variety of water depths and conditions of any of the six survey areas. As a result, four different boats were assigned to work this survey area; the Arlen, the Beach Surveyor, the High Roller, and the Hydro Surveyor. Most of the Bay is very shallow in typical conditions. Working in the winter, when northern weather fronts push water levels even lower than usual, created a very difficult logistical situation and many areas of the Bay could only be surveyed at high tide following several days of calm weather. Hundreds of contacts were identified in the Bay, particularly along the western wedge of the bay adjacent to the remnants of the town of Bay St. Louis. H11618 Sheet C H11618 falls between Long Beach and Biloxi, and includes the Port of Gulfport. The water depths in this area are similar to those in H11616, and two survey vessels were assigned to the survey of this area, the High Roller and Inland Surveyor. The Port of Gulfport was cluttered with debris. For example, multiple obstructions 30 meters long, in all likelihood banana containers, were found in close proximity to the port wall. H11619 Sheet D H11619 is located between Biloxi and Belle Fountaine Pointe. The area includes Biloxi Bay, and its northern boundary was at the highway 90 and Biloxi Bay railroad bridges, both of which were completely destroyed by the Hurricane. In addition, the channel alongside the destroyed Biloxi casinos was surveyed. The 5

6 Arlen surveyed the shallower waters of Biloxi Bay, while the High Roller covered the relatively deeper waters. H11620 Sheet E H11620 is the eastern-most sheet of the survey, between Round Island and Grand Bay. The majority of this survey was water deeper than 6 feet, and could be surveyed with the High Roller. The Hydro Surveyor surveyed the shallower areas. H11638 Sheet F H11638 was not a part of the original project, but was added as a response to a request by the Mississippi Department of Marine Resources. The survey area includes all of Biloxi Back Bay that is deeper than 4 feet. Contacts and obstructions found within the Back Bay included tractor trailers, numerous sunken boats, and even a chimney! Not all of the areas charted as 4 feet or deeper were actually so, and the Arlen was utilized to survey the very shallow areas. The Hydro Surveyor completed the remaining survey area. 6

7 OPR-J977-KR-CC MISSISSIPPI SOUND SURVEY AREAS EQUIPMENT The major operational systems used to acquire hydrographic data include the Odom 200 khz Hydrotrac single beam echosounder, GeoAcoustics side scan sonar systems, and Imaganex shark side scan sonars. PCs were used to collect onboard all vessels, as well as process all data at our Lafayette, La office. All computers were networked to allow for precise time tagging and georeferencing of the data, and for efficient data transfer. SURVEY VESSELS Five separate survey vessels were used for data collection during this survey, the Arlen, Beach Surveyor, High Roller, Hydro Surveyor, and the Inland Surveyor. The Arlen worked in the shallower sections of H11617 (sheet B), H11619 (sheet D), and H11638 (sheet F). The dates of survey for the Arlen are as follows: 7

8 Survey Dates H11617 Oct. 19 Jan. 19 H11619 May 15 Oct. 10 H11638 Jan. 24 Feb. 3 The Beach Surveyor worked in the middle section of H11617 (sheet B). The dates of survey for the Beach Surveyor are as follows: Survey Dates H11617 Nov. 10 Dec. 6 The High Roller collected all of H11616 (sheet A), as well as large sections of H11617 (sheet B), H11618, (sheet C), H11619 (sheet D), and H11620 (sheet E). The dates of survey for the High Roller are as follows: Survey Dates H11616 Dec. 14 Feb. 7 H11617 Nov. 17 Dec. 6 H11618 Oct. 14 Nov. 14 H11619 Sept. 29 Oct. 25 H11620 Feb. 8 Feb. 27 8

9 The Hydro Surveyor worked in H11617 (sheet B), H11620 (sheet E), and H11638 (sheet F), as well as collecting investigation lines in all of the survey areas. The dates of survey for the Hydro Surveyor are as follows: Survey Dates H11617 July 23 Mar. 5 H11620 Feb. 26 Feb. 27 H11638 Feb. 14 Feb. 20 The Inland Surveyor worked in the eastern section of H11618 (sheet C). The dates of survey for the Inland Surveyor are as follows: Survey Dates H11618 Oct. 14 Nov. 14 SINGLE BEAM SONAR OPERATIONS A hull mounted 200 khz Hydrotrac single beam echosounder was installed on board all five survey vessels. Data from the Hydrotrac was continuously recorded and monitored in real-time. If any data displayed navigation or motion correction problems, that line was rerun. 9

10 SIDE SCAN SONAR OPERATIONS The Imagenex Shark side scan sonar was in used in shallow water survey on board the Arlen. The side scan sonar was towed from the bow of the boat, such that the transducers were positioned directly beneath the GPS antennae. A GeoAcoustics side scan sonar system was used to collect survey data on board the Beach Surveyor, High Roller, Hydro Surveyor, and the Inland Surveyor. On board the Beach Surveyor, High Roller, Hydro Surveyor, the towfish was towed from the bow of the vessel resulting in a negligible layback, with the exception of the High Roller, which has a 2.5 meter layback from the GPS antennae. The side scan was towed from an A- frame on board the Inland Surveyor, resulting in a variable layback. Depending upon the local conditions, survey operations were conducted at speeds averaging between 3 and 5.5 knots. The side scan sonars were operated at various range scales, with line spacing set between 30 and 65 meters depending upon the depth of the water. Confidence checks were performed a minimum of once a day. Imagenex side scan collection software was used when collecting data with the Shark. Chesapeake Technologies SonarWiz software was used when collecting with the GeoAcustics. SonarWiz was also used for the processing of the all side scan sonar data. QUALITY CONTROL SINGLE BEAM Single beam data was monitored real time at all times during data collection. In addition, data was reviewed in Caris within 24 hours of its collection. If it was determined that any data quality issues were present, all lines affected would be noted and rerun. 10

11 SIDE SCAN REVIEW PROCESS All data was reviewed at least twice in the field. The side scan operator reviewed all data during collection and noted in the survey logs any significant features or surface/water column effects. Within hours of collection the data was reviewed for a second time by a geoscientist. CONTACT SELECTION As each line was reviewed sonar contacts, as well as existing infrastructure such as aids to navigation, were tagged and recorded. Considering the shallow depths of the water within the survey area, nearly every contact marked could be classified as significant based upon its height. Because this was a 100 percent side scan coverage only survey, every aspect of a potential contact was reviewed; the height off bottom, as well as other characteristics such as dimensions, strength of return, etc. CORRECTIONS TO ECHO SOUNDINGS VESSEL CONFIGURATION CORRECTIONS Prior to survey operations, offsets to the antennas and other survey equipment were measured on board each survey vessel. Offsets were measured from the Central Reference Point (CRP) to all relevant points on the survey vessel (bow, stern, antennas, transducers, etc.) using traditional survey techniques incorporating plumb bobs, tape measures, and digital levels. On board the High Roller and the Inland Surveyor, the CRP was established as an arbitrary point along the central along track axis of the ship within one meter of the multibeam mounting pole. On board the Arlen, Beach Surveyor, and Hydro Surveyor, the GPS antennae were used as the reference point. 11

12 STATIC AND DYNAMIC DRAFT CORRECTIONS Frequent lead line comparisons to the measured single beam depth were used to verify, and correct as needed, the draft of all five survey vessels. The original lead line draft corrections, as well as any subsequent changes to the draft offset, are recorded in the boats survey logs. VESSEL MOTION CORRECTIONS TSS 335B motion compensators were utilized on board the High Roller and Inland Surveyor. TSS DMH B heave compensators were used on board the Beach Surveyor and Hydro Surveyor. The Arlen did not have any motion correction applied to its single beam data. SOUND VELOCITY CORRECTIONS Sound velocity was measured and applied on a daily basis on board the High Roller and Inland Surveyor using Seabird SBE-19 CTD profilers. A sound velocity correction of 1500 m/s was applied to data collected on board all other vessels. VERTICAL AND HORIZONTAL CONTROL Tidal correction data was downloaded from the NOAA website. NOAA CO-OPS supplied tidal zoning for the entire survey area. Three tidal gauges were used, gauge at Bay Waveland Yacht Club, gauge at Gulfport Harbor, and gauge at the Pascagoula NOAA Lab. The following table shows the tidal zone and correctors that were used for this sheet. Tidal data were processed using the epoch. Tide Zone Reference Time Corrector Station (min) Range Ratio CGM CGM CGM CGM

13 CGM CGM CGM The horizontal datum for the survey is the WGS84. The projection is Universal Transverse Mercator (UTM) Zone 16 North. The vertical datum for the soundings is Mean Lower Low Water (MLLW). RESULTS CONTACTS Debris of every shape and size was identified during this survey. In total, 1,389 contacts were marked inside of the six H-numbered survey areas. The total number of contacts per survey area is displayed in the following table. SURVEY AREA NUMBER OF CONTACTS H H H H H H The debris found was not spread evenly through the survey area. The image below shows the locations of all 1,389 contacts. 13

14 OPR-J977-KR-CC MISSISSIPPI SOUND CONTACT POSITIONS There were several areas where high densities of contacts were found. High contact densities were found in Bay St. Louis, Biloxi Bay, and Biloxi Back Bay. The following images depict both areas and contact locations. BAY ST. LOUIS CONTACTS 14

15 BILOXI AREA CONTACTS Although the channels have been cleared, the waters in and around the Gulfport Harbor are still cluttered with debris. The following image displays the location of debris. GULFPORT HARBOR CONTACTS 15

16 DTONS Twenty-seven DTON reports were submitted during the processing of this survey. Examples of the types of dangers reported include damaged or missing navigational aids, numerous visible shipwrecks and pier remains, and large submerged obstructions identified in side scan imagery. INVESTIGATIONS A total of 350 contact investigations were collected following completion of the pregrid survey. The majority of these investigations were collected in surveys H11617, H11618, H11619, and H11638, where the largest amount of debris was seen. AIDS TO NAVIGATION The positions and conditions of 124 aids to navigation were determined. In cases where the aids were missing or damaged, they were reported as DTONs. Otherwise, their position will be reported to be as charted. GRAB SAMPLES A total of 100 grab samples were collected throughout the survey areas. The positions of the samples, along with their attributes, were logged and included in the final report submission. In addition, all of the samples were kept and given to NOAA for further analysis. CHART COMPARISONS The bathymetry data was smoothed to chart scale in order to make comparisons to the charted depth. In general, the survey depths are similar to the charted depths, although there are several instances of shoaling. Numerous obstructions also exist with least depths less than that of the charted depth. All of these obstructions will be recommended for charting. 16

17 DATA SUBMISSION INTERIM DELIVERABLES In order to transmit the positions of dangerous obstructions as quickly as possible to local interests, NOAA required that contact positions and images and progress sketches be submitted on a weekly basis. CONTACT SPREADSHEETS A spreadsheet in a pre-established format that included contact names, positions, and dimensions, as well as other pertinent information concerning contacts, was submitted on a weekly basis. Side scan data was reviewed on a boat-by-boat basis. As a result, several spreadsheets could be submitted every week, depending upon how many boats had worked. CONTACT IMAGES An image of each contact was submitted to accompany the spreadsheets. Images were submitted as html files, and included all ancillary information concerning the contact. Following is an example of a contact image. This contact was also submitted as a DTON Sonar Time at Target: 01/23/ :08:06 Click Position (Lat WGS84): Click Position (Lon WGS84): Map Proj: WGS 1984 UTM, Zone 16 North, Meter Click Position (X): 257, Click Position (Y): 3,341, Acoustic Source File: E:\H11616_HighRoller\H11616hr\XTF\invest2h.xtf Ping Number: 597 Range to Target: Meters Fish Height: 2.08 Meters Event Number: 1 Line Name: invest2h Area / Block: Dimensions Target Height = 0.45 Meters Target Length: Meters Target Shadow: Meters Target Width: 8.13 Meters 17

18 MOSAICS For the coverage map requirement of the interim and final deliverables we submitted side scan sonar mosaics and progress sketches based upon these mosaics. These mosaics were generated in the field and served as another quality control tool. As the geoscientist reviewed the data a mosaic was produced. Any gaps in coverage were noted, logged in the rerun log, and brought to the attention of the party chief. The mosaic images were also overlain with the nautical charts, sonar contact plot and bathymetry data to give a full picture of the survey area. FINAL DELIVERABLES A final report, incorporating all of the survey procedures and results will be submitted to NOAA. CONCLUSION This survey is of significant importance to all of the people who live and work along the Mississippi Coast, where Hurricane Katrina laid waste to so much of the local infrastructure. The results of this survey confirmed what is an obvious assumption; when a hurricane makes landfall, the path of destruction and debris it leaves behind is not limited to only the shore, but extends well away from the coast. Without a proper survey to determine the extent and location of debris left lying submerged, any person and their vessel operating in coastal waters is in danger of striking an unknown object. NOAA acted quickly and efficiently in their response to this massive natural disaster. In turn, C & C Technologies responded just as quickly when given the opportunity to help in the recovery and reconstruction of the Mississippi coast. Working together with NOAA, the positions of over 1,300 contacts have been identified, and transmitted out to local entities as part of an effort to prevent any further disruption to the lives of the people along the coast. 18

19 Hopefully this survey will be an important part of the hard working recovery effort happening along the Gulf Coast, and we will all be able to once again say The Coast is Clear! 19