About the investigation method of the present situation of coral reef at present, the main choice is scuba diving investigation no matter domestic and foreign countries. Take the coral reef of physical examination in Taiwan as example, divers use transects as basic methods to calculate the coverage rate of coral reef and characteristic of the seabed environment and to survey specific fish and quantity of the invertebrate in order to judge the influence that the human activity causes to the coral reef.
In above-mentioned methods can really make full and accurate investigation to the coral reef of monitor area, so the method has already been adopted and walked for many years by the domestic and international relevant organization. But its shortcomings are slower investigating speed and lack accurate fixed position methods, and the divers also have hiding danger. However, some characteristics of side-scan sonar system just can mend the weak points of them. For the speed of investigating, our side-scan sonar's survey range can reach the belt area of hundred meters wide in both route sides, so it can substantially improve the speed of investigating. For the accuracy of fixed position, the side-scan sonar system match to GPS can obtain certain longitude and latitude of targets¡]the precision about 10 m¡^. So, this research is using side-scan sonar system to survey the seabed around LIU-CHIEU YU¡]the survey area about 2.6 km2¡^, the steps contain: mapping the distribute condition¡]sand, mud and rock¡^of seabed bottom, then identifying growing coral reef of rocky area, final assessing its feasibility by the process and result of survey. The ultimate purpose is an attempt to provide a new method for coral reef survey.
The result of study shows: the seabed bottom around LIU-CHIEU YÜ can be divided into several parts by the difference of acoustics reflectivity. Among them, coral reef covers maximum area, and the area can reach to 1,133,670m2¡]46.4% of effective survey area¡^.
In the part of identifying growing coral reef in the acoustics image, this study compares with optics images of TOV and acoustics images of side-scan sonar to establish the characteristics of growing coral reef in the acoustics image. Among them, the tree-like corals have some characteristics about high backscatter, individual risings, tree-like figures and acoustics shadows, unregulated reflection surfaces and complicated color tones in the reflection surface, but the cover-form reefs do not have tree-like figures and acoustics shadows. Then, using the above-mentioned characteristics to identify survey area seabed shows¡GThe cover area of growing coral reef is 547,438 m2¡]22.4% of effective survey area¡^, and the growing coral reef distributes in the southwest, southern and eastern sea area of LIU-CHIEU YÜ. And the optics images of the TOV shows the growth state of growing coral reef in the southeast sea area is superior to the southwest sea area,
Finally, assessed by the process and result of this research, basically it is feasible to map the distribute condition of growing coral reef by side-scan sonar system.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0812104-003333 |
| Date | 12 August 2004 |
| Creators | Yan, Shyh-Bin |
| Contributors | none, none, none, none, none |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0812104-003333 |
| Rights | unrestricted, Copyright information available at source archive |
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