Archive

Marine observation has been integrated into a united network from different platforms of land, sea, and air, which is the inevitable trend of development. Nevertheless the ability to measure undersea environment in China is extremely weak. After reorganizing some developed countries' policies, major projects, and key technical equipment, and analyzing the current issues confronted, some suggestions of development strategy are put forward in this paper as the reference for managers and researchers.

The wave periods play an important role in marine engineering design, especially for the relationships of ocean wave periods. In this study, one year measured wave period data had been applied to investigate the relationships of different wave periods, such as the spectral peak period, significant wave period, the zero-crossing period, the maximum wave period, and so on. The results of this study were compared with those from some literatures and some correlative standards. The corresponding formulae of different wave periods were put forward. Consequently, our results provide support for the marine engineering design and the study of the relationship between wave periods in the South China Sea.

Under the guidance of Changxing platform margin reef reservoir cognition, combination of the 3D and 2D seismic data, analysis of the sedimentary background, development model & ancient physiognomy were studied comprehensivly. In this study, evolution characteristics of reef in Pengxi-Wusheng depression edge in the middle of Sichuan Basin were analyzed, and three development models of reef in Tailai, Yongxingchang and Yihe depression edge in southeast of Sichuan Basin were put forward. Affected by North Kaijiang-Liangping shelf, Emei taphrogenesis & micro-palaeogeomorphology, the reef deposited dominately in depression edge in Tailai,low-energy bioclast-shoals deposited in Yongxingchang and row reef belt and patch reef developed in Yihe. Analysis of sedimentary pattern of Sichuan Basin during Changxing period, the deposition patterns of reef in Pengxi-Wusheng depression edge and Kaijiang-Liangping shelf margin were similar. The vertical developments of reef were in small scale, but the horizontal area distributed widely in depression edge.

The applicability of cathodic protection criteria was studied by surface observation and electrochemical method while the X80 steel was immersed into seawater solution containing SRB. The results revealed:The corrosion was anode control. The corrosion rate was reduced by increasing the SRB adhesion resistance and the charge transfer resistance on the metal surface in the fifth day. While the metal was protected mainly through changing the charge transfer resistance on the metal surface in the tenth day, and the cathodic polarization potential was more negative, the effect was better. The corrosion products were more and poor adhesion on the metal with no-cathodic polarization, and the corrosion products were less and strong adhesion on the metal surface with cathodic protecting. The cathodic polarization could indeed protect the X80 steel in the presence of SRB. In the fifth day, the protection degree was not up to 85% when the metal was polarized to -850 mV_CSE, and it just could meet the protection requirement while polarized to -950 mV_CSE. And in the tenth day the protection degree was declined, it did not meet the requirement while polarized to -850 mV_CSE and -950 mV_CSE. So it was needed to continue to determine the appropriate cathodic protection potential in the presence of SRB.

Combining the remote sensing images and regular data, the continental shorelines at seven periods in Zhejiang were depicted by using the data during the last 100 years. In those seven periods, continental shoreline types and sea reclamation area were calculated and the results are as follows: (1)The spatial pattern of the sea reclamation and way varied from time to time and the proportion of artificial shoreline has been risen from 48.01% to 67.46% during the last 100 years. (2) The relation between the increment of artificial shoreline and the area of reclamation presented three obvious stages from 1913 to 2014: The first stage is that the largest increment of artificial shoreline between 1913-1970 corresponded to the smallest reclamation area change, which meant that people were priority to individual farming during that time. The second stage is that the reclamation area had began to increase rapidly between 1970-1995 while the artificial shoreline reduced, which represented at this time it was collectivized agricultural era. And the third is that the increment of artificial shoreline is relatively small, however, reclamation area increases enormously, which shows that we are now in the stage of both industry and urban land use. (3)The estuarine coastline has been being translated to the sea and the coastline length has increased or decreased. Since 1913, the main estuary reclamation area is about 1 914.85 km², and this is around 76.79% in Zhejiang Province.(4)The major changes in the gulf coast was the blockage of the harbor and the total length of shoreline were being continued to reduce in the last 100 years. Since 1913, these three harbors’ reclamation area is 429.32 km², and it is about 17.22% in Zhejiang Province.

The coastal artificial morphology construction is an important way for coastal countries to exploit the coastal resources. The formation of coastal artificial shoreline changes the pattern of natural shoreline, and influences the succession laws of the natural shoreline. In this study, the mainland coastline in Zhejiang Province in different times was extracted, based on TM remote sensing images in 1990, 2000 and 2010, the structure of mainland coastline and the influence of artificial shoreline construction on the patterns of the coastline in Zhejiang Province were analyzed. The results show that: (1) Affected by the development activities of human, the mainland coastal landscape in Zhejiang Province was characterized by the continued growing of the proportion of the artificial shoreline in recent 20 years. (2) The speed of artificial shoreline construction had significantly differences at different coastal area, especially at the Hangzhou Bay, the Sanmen Bay and the Taizhou Bay. (3) In these 20 years, coastal erosion and retreat occurred at only a small part of mainland coastline in Zhejiang Province. As a whole, it was advancing to the sea obviously. (4) The construction of artificial shoreline shortened the length of natural shoreline and reduced the tortuosity of natural coastline in Zhejiang Province in the process of straightening, but increased the diversity index of the continental coastline.

The Baishamen beach of the Qiongzhou Channel is an important resource for the Haikou city's tourism, but the previous researches presented that it has been in erosion from 1960. The waterlines in 19 Landsat sensing images from 1994 to 2015 were extracted, which were used to calculate the beach slope and analyze the beach erosion and accretion. The results show that the beach was mainly in erosion from 1994 to 2008, the waterline moved 104.71 m to the shore near the high tidal level and 95.49 m to the shore near the low tidal level, but the artificial sand filling in the time around 2000 compensated the erosion. While the beach was mainly in accretion from 2008 to 2015, the waterline moved 34.17 m to the sea near the high tidal level and 25.93 m to the sea near the low tidal level, which may be induced by the Xinbu Island enclose engineering.

Retrieval of offshore bathymetry has important significance in shallow topographic survey, coastal protection and development. In this study, Dongluodao waters in South China Sea was taken as a typical study area, using the SPOT-6 6 m high resolution data, six band ratio model such as blue-green and blue-red were set up respectively based on SPOT-6 multi-spectral data and depth measured values. The results show that green-red band ratio model has the highest accuracy and the R² value reaches 0.706 4. This has certain reference significance for retrieval of offshore bathymetry in tropical oceans. Comparing with the average relative error of the different depths range based on the above model, the conclusion is that the depth range from 0 to 5 m has the higher average relative error, mainly because the conditions are complex. The depth range from 5 to 10 m has a minimum average relative error of 13.62%. Accretion of the average relative error with the increasing of the depth, while SPM, CDOM and chlorophyll concentration are the main causes of this phenomenon.

Attaching a spoiler on the top of pipeline is a new method to enhance self-burial of pipeline. The pipeline state in Hangzhou Bay with spoiler was investigated in this study in order to understand the mechanism of spoiler. Based on the route survey data combined with the seabed and hydrodynamic characteristics, the effect of spoiler on self-burial of pipeline was discussed. The survey data illustrate that the percentage of buried pipeline increased from 50% in 2005 to over 80% in 2013, and the average buried depth increased to 2.60 m, which shows that this self-burial method is applicable in this region. While some sections of the pipeline where the flow direction is parallel to the route or on strong anti-erosion river bed are still exposed on the seabed due to the ineffectiveness of spoiler.

To automatically sample mesoscale eddies by AUVs, the method to automatically recognize the dynamic features of eddies must be developed. In this study, a method for dynamic feature detection of mesoscale eddies was created based on SLA (Sea Level Anomaly) data. The main innovation is that a criterion to decide the succession relations of eddies was developed. With the succession relations of eddies being confirmed, we can calculate the area changing rate of eddy region, velocity of eddy centroid movement and some other dynamic features. Since the calculation cost of this algorithm is not enormous, it can be used in real time eddy tracking context, such as tracking eddies with AUVs. It is worth noting that SSH(Sea Surface Height) data can also be used in this algorithm. And SLA or SSH data can be acquired from the ocean numerical simulation model, satellite remote sensing or other methods. As long as SLA or SSH data are provided, our algorithm can be easily utilized for dynamic feature detection of mesoscale eddies.

Operational ocean observation instruments (OOOI) lay a solid foundation for operational ocean observation system. Typical OOOI of ocean observing station in China and the U.S. were analyzed comparatively in terms of performance indexes. Then current status and trends of OOOI in the world were described and the prior developing technology of OOOI in China was discussed. The results show that the accuracy of tide gauge is one order of magnitude lower than that in comparing with the U.S., and the accuracy of wave height, period and wave direction are 0.2 m, 0.27 s and 5°~10° lower than those of U.S., respectively. Moreover, operation reliability and stability have also shortcomings. In the world, the ocean observation equipment is becoming more informative, intelligent, professional and modular. Besides, their functions are being perfected through serialization development and the reliability is increasing more and more. Under this trend, high-precision sensor and materials, anti-biological fouling and corrosion protection techniques as well as intelligent electronic circuit, artificial intelligence and automation techniques have the higher priority for developing OOOI in China.

Ultra short baseline positioning system can provide accurate positioning information for underwater equipment. The positioning results of the ultra short baseline positioning system contain a variety of factors, the effective processing of the data is the essential prerequisite for position precision. In this study, the acoustic antenna was calibrated, the accuracy of the positioning data was evaluated, the maritime collecting data were analyzed and the gross points of the raw data were filtered and removed. Finally, the reliable results of underwater positioning thereby can be acquired.

In order to meet the requirements of fast and multi-factors monitoring of the marine environment, a kind of shipborne automatic sampling system (SASS) was developed. SASS has a simple and flexible operation system, and has three control modes: automatic, semi-automatic and manual mode. The hardware of SASS mainly consists of pump, composite cable, electric winch, electric control cabinet and storage tank. With the control of the software, the devices such as winch and collecting pump can open and close automatically, to complete the collection of multi-level seawater samples in same site. Compared with the traditional method, this system can greatly reduce the labor intensity of the experimenters, and improve the precision of sampling depth. After a large number of sea trials in the Bohai Sea and in the East China Sea, SASS has been proved to be stable.

In order to solve the sound source measurement problem in the non-free sound field of reverberation environment, a method of sound field reconstruction was presented. In this method, we took measurement, analysis and reconstruction of the sound source. We chose the anechoic tank and reverberation tank as the experimental environment, the transducer as the simulation object, the hydrophone array as the frontend measurer. By using the single layer hydrophone array, the sound pressure distribution of non-free sound field was measured. Sound wave separation was conducted for the measurement results. The sound pressure distributions before and after the sound wave separation were respectively compared with those in the anechoic tank. At last we calculated the errors of sound field reconstruction. The sound field reconstruction errors were presented when the source frequencies were 5 000 Hz and 7 000 Hz. The results show that this sound wave separation method based on sound pressure measured by the single layer hydrophone array can reconstruct the sound field in reverberation environment accurately.