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IOC Sub-Commission for the Western Pacific (WESTPAC)

Advancing knowledge and cooperation for a healthy ocean and prosperous society

Scientists study sediment discharge to improve environment in the Western Pacific

Regional scientists gathered for the first time in Thailand to investigate fluvial sediment discharge to the South China Sea.

Over 20 scientists from eight Western Pacific countries recently met at UNESCO’s Intergovernmental Oceanographic Sub-Commission for the Western Pacific workshop, to share and discuss new scientific findings on the study of fluvial sediment supply to the South China Sea at the Department of Marine Science, Chulalongkorn University in Bangkok. The participants came from China, India, Indonesia, Malaysia, Philippines, Thailand, and Vietnam.

This is the fourth international workshop that provides a platform for scientists from various relevant backgrounds to present their studies on fluvial sediment records both on land and in the South China Sea.

“We hope to develop the history and study the change of environment and climate from past to present which the South China Sea has been facing,” said Wahyoe Soepri Hantaro from Center Research for Geo-technology, Indonesian Institute of Sciences.

“What we try to study together, different subjects and different methods could become important scientific findings about the past and present and we could predict what the future condition we will see in the region.

“Our people can be better prepared to live in the future with much better environment conditions,” he said.

Mr. Hantaro presented two papers in this workshop, first on environment change in Lake Sentarum West Kalimantan: data from clay mineralogy, and second on Low Sea level and sedimentation pattern in Sunda Platform: coastal plain and delta development.

As the largest marginal sea in the Western Pacific, the South China Sea receives approximately 570 million tons of fluvial sediments annually through numerous rivers in adjacent continents and islands, including some of the world’s largest rivers such as Pearl, Red, and Mekong, small mountainous rivers, for example, rivers in middle Vietnam, southwestern Taiwan, and Luzon, and from the Gulf of Thailand which receives sediments from several large rivers, such as the Chao Phraya, Mekong, and Bang Pakong. The river-borne sediments have formed high sedimentation-rates and deposits which are mostly on the shelves of the South China Sea, and have recorded anthropogenic and natural climatic changes occurring in land source regions.

“For a moment we don’t know how sediment is formed,” said Prof. Dr. Zhifei Liu from Laboratory of Marine Geology, Tongji University in China. “Usually it is formed by weather, but since the weather has changed, we don’t have information on the formation of sediment. Likewise, for this moment we don’t know how sediment is transported within the sea and how it is mixed in the ocean.

“We need to know what kind of sediments are in the river to build the dam. We need to investigate the quality of water and evaluate the effect of human activities. We need to know what nature thinks. In this project we try to provide answers, and the countries around the South China Sea can benefit from the knowledge in different ways, like coastal management and hazard protection,” said Mr. Liu.

The project “Fluvial Sediment Supply to the South China Sea: Anthropogenic and Natural Aspects (FluSed)” was initiated by the Intergovernmental Oceanographic Commission (IOC) Sub-Commission for the Western Pacific (WESTPAC) to understand how human activities affect sediment discharge and develop scenarios of future changes. Its first phrase started in May 2008 to May 2010 and the second phase is from May 2010 to May 2012. It aims to investigate fluvial sediment discharge to the South China Sea, to determine source and transport of sediments in the South China Sea during the geological past, and to predict the future sediment discharge.

Wenxi Zhu, Head of UNESCO/IOC Regional Office for WESTPAC said: “With the joint efforts of the project group, these objectives have been achieved as evidence by a number of joint activities conducted among participant countries.”

In its first phase of implementation, workshops and joint sampling provided a platform for scientists surrounding the South China Sea and in other regions to share their scientific knowledge, address data gaps and stimulate new ideas on the study of the fluvial sediment discharge. The first and second workshops were held in Tongji University at Shanghai, China in November 2008 and 2009 consecutively, and the third workshop was held in Quezon City, Philippines in November 2010. This fourth workshop was held in Thailand on 14-16 December 2011.

“In the past three years we have completed collecting the samples from all the rivers in South China Sea and the data is ready to be analyzed and later published,” said Mr. Liu, Project Leader from China.

“We have signed many bilateral agreements and MOU [Memorandum of Understandings] and have a number of exchange students between universities in different countries.

“We have very active working groups,” he said.

In this three-day workshop Mr. Liu presented his study titled source to sink process of detrital fine-grained sediments in the South China Sea: a clay mineralogical approach.

Assistant Prof Dr Penjai Sompongchaiyakul, lecturer at Chulalongkorn University and workshop participant said the study of marine geology would not have been possible without collaboration from different countries.

“It costs a lot. Usually no single country would invest in the study alone as each country’s budget on this subject is quite limited. About 70 to 80 per cent of the budget would go for the ship to investigate in the sea, and the equipment and analysis is very costly,” she said.

Ms. Penjai presented her paper on using acid volatile sulfide-simultaneous extracted metals as an assessment tool for metal pollution risk in the Upper Gulf of Thailand.

In welcome remarks Associate Prof Dr Thaithaworn Lirdwitayaprasit, head of Department of Marine Science of Chulalongkorn University suggested a topic for discussion on flooding in Thailand.

“Since Thailand has been affected by the massive flood, the huge amount of sediment will be transported into the inner gulf also, this may be an interesting topic for your discussion or as a model for the study in the future.

“I believe that the opportunity to share the knowledge during this workshop is quite important for more understanding of the ocean in WESTPAC region.”