Copicut Reservoir Sidescan Sonar. Fall River, MA May 7, 2013

Transcription

1 Copicut Reservoir Sidescan Sonar Fall River, MA May 7,

2 Table of Contents Section 1: Mission Overview... 3 Background... 3 Vehicle General Information... 3 Vehicle Mission Details... 4 Area of Operation... 4 Perimeter Mission Track... 5 Dam Mission Track... 6 Sites of Interest... 7 Section 2: Klein 3500 Sidescan Sonar Images... 8 SonarWiz5 Processing... 8 Mission 1: Perimeter Region... 8 Mission 2: Dam Subsurface Region Section 3: Mission Summary Summary:

3 Section 1: Mission Overview Background: In 1973, the City of Fall River, MA, converted an old quarry into a body of water known today as Copicut Reservoir. The lake serves as the reserve water supply to North Wattupa Pond, Fall River s primary drinking water supply. Recently, the Fall River Water Department requested an evaluation of the integrity of the reservoir s shoreline and an investigation into possible signs of erosion alongside the embankment of the Copicut Reservoir Dam. Working in association with the Fall River Water Department, UMass Dartmouth s Coastal Systems Technology (CST) group performed a preliminary survey of the perimeter and dam subsurface regions of the reservoir utilizing underwater acoustic imaging technologies. The two missions were conducted using a small man-portable Iver2-AUV equipped with a highresolution Klein 3500 sidescan sonar system (see Figure 1 bellow). Figure 1: A man-portable Iver2 AUV equipped with Klein sidescan sonar Vehicle General Information: Table 1: Vehicle General Information Participants Coastal Systems Technology (CST), OceanServer Technology, Inc. Vehicle Identification no. 167 Active sensors DVL, Klein 3500 Sidescan Sonar Operating area Copicut Reservoir Fall River, Massachusetts, USA Date and day of run Tuesday, 7 May

4 Vehicle Mission Details: Table 2: Vehicle mission details for each mission Mission # Region Duration (hr:min:sec) Number of Waypoints Vehicle depth from surface (ft) Speed of vehicle (kn) 1 Perimeter 1:16: Dam 0:23: subsurface Area of Operation: Figure 2: Copicut Reservoir Figure 2 is a satellite image of Copicut Reservoir. 4

5 Perimeter Mission Track: Figure 3: Perimeter mission track In Figure 3, the perimeter mission track is superimposed on a satellite image of Copicut Reservoir. 5

6 Dam Mission Track: Figure 4: Dam Subsurface mission track Figure 4 displays the dam mission track overlaid on a satellite image of Copicut Reservoir. 6

7 Sites of Interest: Figure 5: Sites of interest In Figure 5, Klein 3500 images acquired from the perimeter and dam subsurface missions are overlaid on the satellite base-map of Copicut Reservoir. 7

8 Section 2: Klein 3500 Sidescan Sonar Images SonarWiz5 Processing: During the post-processing phase of the project, the CST team utilized Chesapeake Technology s SonarWiz5 software to render the high-resolution Klein 3500 sonar images acquired during the missions. The pictures corresponding to the perimeter and dam subsurface missions are depicted below. Image properties such as sidescan range, vehicle depth from surface (DFS), and vehicle speed are provided for each set of images. Mission 1: Perimeter Region Table 3: Perimeter Region Image Specifications Sidescan type Klein 3500 Frequency enabled 900 khz Sidescan range 60 m Speed of vehicle underwater 2.5 kn DFS 0 ft Figure 6: Site 1 Figure 6 is a discarded pile of granite. Figure 7 shows a close-up view of the same feature. 8

9 Figure 7: Magnified image of Site 1 Figure 8: Site 2 9

10 Figure 8 shows the contour of the shoreline and a possible walkway. Figure 9: Site 3 The bottom depicted in Figure 9 is mostly flat with sand. Several piles of rocks lay on the bottom of the reservoir. 10

11 Figure 10: Site 4 Figure 10 shows the contours of the shoreline, depicting open flat sandy regions, as well as large rocky areas. 11

12 Figure 11: Site 5 Linear patterns of rocks are indicated in Figure

13 Mission 2: Dam Subsurface Region Table 4: Dam Subsurface Region Image Specifications Sidescan type Klein 3500 Frequency enabled 900 khz Sidescan Range 60 m Speed of vehicle underwater 2.5 kn DFS 3 ft Figure 12: Site 6 Figure 12 depicts the edge of the dam (the broad lightly colored band) and two ridges in the shoreline just past that. Figures 13 and 14 are magnified screenshots of the dam subsurface embankment. Figure 13: Magnified image of Site 6 13

14 Figure 14: Magnified image of Site 6 Section 3: Mission Summary Summary: A small man-portable Iver2-AUV equipped with a high-resolution Klein 3500 sidescan sonar system was sent into Copicut Reservoir to collect underwater acoustic images of the shoreline and dam subsurface. During post-processing, Chesapeake s SonarWiz5 software was the enabling technology that was utilized to generate high-resolution imagery of the bottom features of the reservoir. These detailed pictures provided a comprehensive idea of the integrity of the reservoir s shoreline, as well the structural characteristics of the Copicut Reservoir Dam. Several abandoned piles of rocks observed near the shoreline of Copicut Reservoir offer supporting evidence of the area s previous quarry operation. After inspection of the dam subsurface region, it can be concluded that no anomalies were detected in the dam face. 14