1、3515789 070971b 933 = US Army Corps of Engineers Waterways Experiment Station Technical Report CHL-97-22 December 1997 Results of Monitoring Study of Agat Harbor, Guam by DavidD. McGehee, WES Stanley BOC, Pacific Ocean Division Approved For Public Release; Distribution Is Unlimited Prepared for Head
2、quarters, U.S. Army Corps of Engineers Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endor
3、sement or approval of the use of such commercial products. The findings of this report are not to be construed as an official Department of the Army position, unless so desig- nated by other authorized documents. Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
4、om IHS-,-,-Technical Report CHL-97-22 December 1997 Results of Monitoring Study of Agat Harbor, Guam by David D. McGehee U.S. Army Corps of Engineers Waterways Experiment Station 3909 Halls Ferry Road Vicksburg, MS 391 80-61 99 Stanley Boc US. Army Engineer Division Bldg. 230 Fort Shater, HI 9fj858-
5、WO I Pacific Ocean Final report Approved for public release: distribution is unlimited Prepared for US. Army Corps of Engineers Washington, DC 2031 4-1 O00 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_ = 3515789 0709719 b42 Waterways Experiment S
6、tation Cataloging-in-Publicatation Data McGehee, David D. US. Amy Corps of Engineers. Resuits of monitoring study of Agat Harbor, Guam / by David D. McGehee, Stanley Boc ; prepared for 180 p. : ill. ; 28 cm. - (Technical report ; CHL-97-22) Includes bibliographic references. 1. Breakwaters - Guam. 2
7、. Harbors - Guam. 3. Ocean waves - Guam. 4. Water waves - Guam. 5. Agat Harbor (Guam) I. BOC, Stanley J. II. United States. Army. Corps of Engineers. 111. U.S. Army Engineer Waterways Experiment Station. IV. Coastal and Hydraulics Laboratory (US. Army Engineer Waterways Experiment Station) V. Title.
8、 VI. Series: Technical report (U.S. Amy Engineer Waterways Experiment Station) ; CHL-97-22. TA7 W34 no.CHL-97-22 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- 3535787 O709720 364 Contents Preface vi Conversion Factors. Non-SI to SI Units of Measur
9、ement viii 1-introduction . 1 2-Project Description 2 Site Description 2 DesignCriteria . 3 DesignMethods 4 3-MonitoringPlan 7 Objectives 7 Monitoring Elements . 8 Analysis and Sampling Plan . 16 System Installation . 17 The Unanticipated Monitoring Element . 18 path and observations 29 Wave transfo
10、rmation; pressure time series . 30 Energy spectra for sites 1B (a) and 2A. 2B. and 4A 0) on 10/16/92 O600 hr 31 Energy spectra for sites 1B (a) and 4A (b) on 8/06/93 1600 hr . 32 Pressure thne series at site 2-M for typhoons Omar and Brian 33 Breakwatersurface . 35 One-hour “blow-up” of oscillations
11、 at sites 2-M and 3.0. 25October 36 Schematic representation of reef flat circulation/oscillation . 40 iv Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- 3515789 D709722 137 List of Tables Table 1 . Sampling and Analysis Scheme for Onshore System .
12、16 Summary of Reef Flat Wave Transmission Events . 29 Table 2 . Table 3 . Seiche Modes for a Rectangular Basin . 38 V Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-W 353578% 0709723 073 Preface This report was prepared by the U.S. Army Engineer Wat
13、erways Experiment Station (WES) Coastal and Hydraulics Laboratory (CHL), which was formed in October 1996 with the merger of the WES Coastal Engineering Research Center and Hydraulics Laboratory. Dr. James R. Houston is the Director of CHL and Messrs. Richard A. Sager and Charles C. Calhoun, Jr., ar
14、e Assistant Directors. The report is a product of the Monitoring Completed Navigation Projects (MCNP) Program and represents a joint effort between CHL and the Pacific Ocean Division (POD) of the U.S. Army Corps of Engineers. The MCNP Program Manager was Ms. Carolyn Holmes, CHL. Program Monitors of
15、the MCNP Program at Headquarters, U.S. Army Corps of Engineers were Messrs. John Lockhart, Barry Holliday, and Charles Chesnutt. The Principal Investigator of the Agat Harbor Work Unit was Mr. David D. McGehee; and the seiche and current measurement program was conducted by Dr. David King, both of C
16、HL. During the course of this study they were supervised by Mr. William Preslan, Chief, Prototype Measurement and Analysis Branch (PMAB), and Mr. Thomas Richardson, Chief, Engineering Development Division, CHL. The POD Co-Principal Investigator was Mr. Stanley Boc. Coordination and local management
17、at POD were the responsibilities of Mr. Frank Dayton, Environmental Engineer in the Guam Operations Office. Messrs. Boc and Dayton were supervised by Mr. George Young, Chief of the Civil Works Technical Section, Planning and Operations Division. Local technical support on Guam was provided by Mr. Pa
18、ul Tobiason, of Datacomm, Inc., Mr. Dean Henley of Integrated Systems Analysis, Inc., and Pacific Basin Environmental Consultants, Inc. Special thanks are owed to the U.S. Coast Guard Station on Guam and the crew of the USCG Cutter Basswood. Permission to use facilities at Agat and other logistics a
19、ssistance were provided by the Port Authority of Guam. Their contribution to the study is gratefully acknowledged. The following CHL personnel contributed to this study: the remote monitoring system and its software were designed by Messrs. Jay Rosati and Gary Howell. Installation of the system was
20、planned by and conducted under the supervision of Mr. William Kucharski. Data analysis vi Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-m 3515789 09061724 TOT m and plotting were accomplished by Mr. James McKinney and Ms. Margaret Sabol. At the tim
21、e of publication of this report, Director of WES was Dr. Robert W. Whalin. Commander was COL Robin R. Cababa, EN. The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an oficial endorsement or approval of th
22、e use of such commercial products. vi i Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-m 3535789 0709725 946 = 1 Conversion Factors, Non-SI to SI Units of Measurement Multiply BY To Obtain feet 0.3048 meters Non-SI units of measurement used in this
23、report can be converted to SI units as follows: inches knots (international) miles (U.S. nautical) pounds (mass) pounds per square inch 2.54 centimeters O. 1 51 44444 1.852 kilometers 0.4535924 kilograms 6.89 kilopascal meters per second viii Provided by IHSNot for ResaleNo reproduction or networkin
24、g permitted without license from IHS-,-,-3515789 0?0972b 882 1 Introduction The Monitoring Completed Coastal Projects (MCCP) Program was estab- lished by Headquarters, U.S. Army Corps of Engineers (HQUSACE) in 1981 to evaluate the performance of the Corps in planning, design, construction, and opera
25、tion and maintenance of selected Civil Works coastal projects. The program was renamed Monitoring Completed Navigation Projects (MCNP) in October 1996. The MCNP is funded by the Operations and Maintenance (O Figure 4 shows the completed project prior to construction of berthing and shoreside facilit
26、ies. The original design and survey data were provided in English units. Data collected for this study are reported in metric units, with the exception of some overwater distances, which are provided in nautical miles, foliowing nautical convention. See page viii for conversions. 2 Chapter 2 Project
27、 Description Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-= 3515789 0709728 b55 jF I - - - - aofiaF$ miid bottom slopes; and no current (Chen and Houston 1986). 4 Chapter 2 Project Description Provided by IHSNot for ResaleNo reproduction or networ
28、king permitted without license from IHS-,-,-Figure 3. Agat Harbor channel under construction Amplification factors were calculated for incident energy in 1-sec interval period bands from 8 to 20 sec and approaching from three incident angles. Output was reported at 32 locations (grid elements) withi
29、n the harbor for the two initial plans and three alternative plans. The outer boundary of the numerical grid was within the reef flat. Three water levels were tested: 0.72 m, 1.4 m, and the 2.2 m design condition. The final plan recom- mended, Plan 4, extended the north end of the detached breakwate
30、r by 45 m from the original design (Farrar and Chen 1987). Breakwater Breakwater design was accomplished using standard practices found in the 1977 Shore Pro?ection Manual. The Hudson formula was used to select the armor size for the design wave height. The design wave for the structure was selected
31、 as the depth-limited breaking wave at the structure toe, or 0.78 h, where h = water depth. The design depth assumed for the constructed plan was 2.5 m, derived from a mean higher high water level of 0.7 m, plus an estimated combined surge and wave setup of 1.4 m, over a reef flat with an average el
32、evation of 0.3 m. The resulting design wave is 1.9 m. Chapter 2 Project Description 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3515789 070S31 L4T Figure 4. Agat Harbor under construction 6 Chapter 2 Project Descnpon Provided by IHSNot for Resa
33、leNo reproduction or networking permitted without license from IHS-,-,-3535789 0709732 D8b D 3 Monitoring Plan Objectives Agat Harbor was selected for monitoring because it has potential for pro- viding information on an environment for which littie engineering data exist. Design guidance on wave ch
34、aracteristics on cord reefs needs improvement, as most data on wave shoaling and breaking are derived from observations of waves approaching sandy shorelines. Figure 5 contrasts the offshore profile at Agat with the typical equilibrium beach profile. Wave transformation across I 2 km I 1 km -0 -6 m
35、-30 m - 100 m Figure 5. Idealized reef and sand beach profiles Chapter 3 Monitoring Pian 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-= 3515789 0799733 T12 this regime can be expected to be markedly different than across sand beaches. Even less
36、information is available on maximum surge levels behind reef shore- lines. How these factors affected the selection of the design parameters was an important but difficult question. The answer required observations during conditions at or near the design wave and surge conditions or at least condi-
37、tions sufficiently energetic to cause structural damage. Unless a typhoon approached from the west during monitoring, there would be no opportunity to assess breakwater stability. Shoaling of the channel at the entrance was not expected because it was cut through limestone, and exited the live reef
38、face where the water depth was well below project depth. Neither were impacts on adjacent shorelines anticipated, since there was little erodible material on the reef flat and upland areas. Nevertheless, the monitoring plan included periodic inspections of the structure and surrounding shoreline. Th
39、e major issues to be addressed in the study were as follows: a. b. C. d. e. f. Deepwater incident wave climate for the region around Guam. Wave transformation across coral reefs as a function of depth and dis- tance from the reef face. Wave and surge levels behind coral reefs during large wave event
40、s (distant storms to the west would produce large incident waves, even without a local typhoon). Validation of the HARBS model. Wave transformation down steep-sided channels. Response of project and adjacent shoreline. Monitoring Elements A monitoring plan was developed to examine these issues throu
41、gh analysis of data collected over a 3-year observation period (Boc and McGehee 1989). Elements of the monitoring effort are related to the study issues. As is usually the case with coastal engineering field studies, the “ideal” monitoring plan had to be modified to accommodate instrumentation, logi
42、stic, and economic con- straints. The elements of the plan, referenced by letter to the issues are as follows: a. Directional wave energy spectra and surface winds from an offshore site. 8 Issue g, “Wave-induced circulation on a reef flat,” is discussed on pages 18 and 19. Chapter 3 Monitoring Plan
43、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-b. Wave energy spectra at several locations on a shore-normal transect across the reef flat. c. Wave conditions and water elevations at the structure, and harbor response during large wave events. d. (1
44、) Directional wave energy spectra at the outer boundary of the model. (2) Wave energy spectra at several sites within the harbor. e. Wave energy spectra at the outer and inner ends of the channel. f. Periodic site inspections and aerial photographs of the harbor and surroundings. Element a requires
45、a long, continuous record to obtain the distribution of calm conditions as well as the extreme events that describe the wave climate. Elements b-e require a range of conditions above some threshold of interest, ideally including the modeled incident conditions. In order to capture a suffi- cient ran
46、ge of conditions, including episodic events, it was considered desirable to monitor these sites continuously over the course of the study. Periodic measurements or experiments were not considered initially because of the difficulty of synchronizing measurements with events of interest and because th
47、ese events develop rapidly, making it difficult to fix instruments securely in place before conditions become too violent for placement. The preferred position for measuring the incident climate is directly off- shore of Agat in deep water. These depths are attained relatively close to shore, but in
48、strument constraints, discussed below under “System Design; Data management,” forced a position further offshore. Initially, a site southwest of the island (1A) was selected; a second site to the northwest (IB) was desig- nated to improve performance (see Appendix B, “Performance Critique”). Gauge placement in the channel and harbor posed no particular logistic restrictions, allowing sites to correspond to the channel beginning and end (sites 5A and 5B), and with three of the HARBS model grid points (sites 4B 4D). Site 5A also represents incident wave condit
