Guidelines for Marine Archaeological Investigation (MAI)
The standard practice for MAI should consist of four separate tasks, i.e. (1) Baseline Review, (2) Geophysical Survey, (3) Establishing Archaeological Potential and (4) Remote Operated Vehicle (ROV)/Visual Diver Survey/Watching Brief.
(1) Baseline Review
1.1 A baseline review should be conducted to collate the existing information in order to identify the potential for archaeological resources and, if identified, their likely character, extent, quality and value.
1.2 The baseline review will focus on known sources of archive data. It will include:
a. Geotechnical Engineering Office (GEO) – the Department holds extensive seabed survey data collected from previous geological research.
b. Marine Department, Hydrographic Office – the Department holds a substantial archive of hydrographic data and charts.
c. The Royal Naval Hydrographic Department in the UK – the Department maintains an archive of all survey data collected by naval hydrographers.
1.3 The above data sources will provide historical records and more detailed geological analysis of submarine features which may have been subsequently masked by more recent sediment deposits and accumulated debris.
(2) Geophysical Survey
2.1 Extensive geophysical survey of the study area should be deployed by using high resolution boomer, side scan sonar and an echo sounder. The data received from the survey would be analysed in detail to provide:
a. Exact definition of the areas of greatest archaeological potential.
b. Assessment of the depth and nature of the seabed sediments to define which areas consist of suitable material to bury and preserve archaeological material.
c. Detailed examination of the boomer and side scan sonar records to map anomalies on the seabed which may be archaeological material.
(3) Establishing Archaeological Potential
3.1 The data examined during Tasks 1 and 2 will be analysed to provide an indication of the likely character and extent of archaeological resources within the study area. This would facilitate formulation of a strategy for investigation.
3.2 The results would be presented as a written report and charts. If there is no indication of archaeological potential there would be no need for Task 4.
(4) Remote Operated Vehicle (ROV)/Visual Diver Survey/Watching Brief
4.1 Subject to the outcome of Tasks 1, 2 and 3, accepted marine archaeological practice would be to plan a field evaluation programme to acquire more detailed data on areas identified as having archaeological potential. The areas of archaeological interest can be inspected by ROV or divers. ROV or a team of divers with both still and video cameras would be used to record all seabed features of archaeological interest.
4.2 Owing to the heavy marine traffic in Hong Kong, the ROV/visual diver survey may not be feasible to achieve the target. If that is the case, an archaeological watching brief is the most appropriate way to monitor the dredging operations in areas of identified high potential to obtain physical archaeological information.
4.3 A sampling strategy for an archaeological watching brief would be prepared based on the results of Tasks 1, 2 and 3 to focus work on the areas of greatest archaeological potential. Careful monitoring of the dredging operations would enable immediate identification and salvage of archaeological material. If archaeological material is found, the AMO should be contacted immediately to seek guidance on its significance and appropriate mitigation measures would be prepared.
4.4 If Task 4 is undertaken, the results would be presented in a written report with charts.