Sediment Problems - Matter of Global Concern

In the twenty-first century, humanity will be confronted with three major problems, namely rapid increase in population, shortage of natural resources and protection of the environment. There will be a pressing demand for more land and water resources, more raw materials and a decent environment with more balanced ecology for people to live in. Sediment problems in general, including those arising from land erosion, sediment transport in streams and sediment deposition in reservoirs and lakes, will directly affect the rational development of water and soil resources, the control of floods in rivers and the protection of the environment as well as ecology in river basins and hence will impact all the three problems listed above.

According to preliminary sediment statistics available for the world, the annual erosion of surface soil from river basins amounts to 60 billion tons, of which 17 billion tons are discharged into the oceans. In the process, as much as 5 to 7 million ha of farmland are annually ruined and about 1% of the precious storage capacity of the world's reservoirs is annually lost to deposition.

In addition to the loss of flood-control storage due primarily to reservoir deposition, there are numerous instances of aggravation of flood disasters and deterioration in ecology and environment caused by erosion and deposition of sediment. Extensive erosion of bare lands by water or wind has intensified desertification and turned the rivers turbid, after depriving the land of good top soil. Aggradation due to heavy deposition of sediment in river channels has transformed the downstream reaches of many rivers into “perched” rivers with beds higher than the riparian valley floor. This adverse situation has increased the risk of major breaches of levees and led to heavy casualties and loss of properties in case of levee failures, accompanied by extensive damages to the surrounding environment and ecology through extensive flooding. Steep slopes with a loosely formed soil surface and lack of adequate vegetative cover under torrential storms have often triggered debris flows, which devastate both rural and urban areas. Slope disintegration, another form of soil erosion, along with landslides, has caused extensive movement of coarse materials downhill to cover much of the once fertile land in foothill regions. In some cases the loss of such farms has driven tens of thousands of farmers to flee from their homes to search for new lives elsewhere. Adsorption of nutrients and heavy metals onto fine sediments deposited in reservoirs has contaminated the water of many reservoirs and lakes through eutrophication and other biological as well as chemical processes. Heavy sediment deposition in river channels, harbours and estuaries has impeded inland navigation, especially the passage of large vessels between inland metropolitan areas and important coastal cities.

The sediment problems described briefly in the foregoing are typical ones, which have constituted the core of sediment research in the past. There are more sediment problems and their possible solutions yet to be addressed in the future. Only the sound management of erosion and sedimentation may contribute to the mitigation of sediment problems and help strive toward the sustainable development of natural resources, especially soil and water.

It is probably apt to quote Sundborg and Rapp of Sweden [ ( 1986 ] ) herein: “The accelerated rate of technical development, the rapid increase in world population and the great need for more food and energy have drastically increased the impact of human activities during recent decades. Problems of soil erosion and sedimentation may prove to be some of the most serious obstacles to future development. These problems are felt all over the world. In this sense, they are a matter of global concern.”

The Need for More Comprehensive Organization to Promote Sediment Research

Although the erosion , transport and deposition of sediment are natural phenomena, their scales and impacts on other related problems are greatly influenced by human activities. For example, the economic development of human societies is by and large accompanied by the unceasing exploitation of land and waters, such as oceans, lakes and rivers, at a constantly escalating scale and with increasing intensity. As a result, sediment problems are becoming increasingly grave and demands for their solution increasingly urgent.

Although sediment problems have resulted from natural events, they are closely related to social, economic and other human activities. Therefore, the sound solution of sediment problems must come from the concerted efforts of experts in various fields concerned and is thus always interdisciplinary. The disciplines involved may include soil conservation, environmental science and engineering, ecology, hydrology, fluvial geomorphology and hydraulics, applied mathematics, geography, sedimentology, hydraulic engineering, hydro-power engineering, agriculture, water supply, irrigation and drainage engineering, navigation, forestry, coastal engineering, isotope hydrology, remote sensing, chemistry, soil science, biology, municipal engineering, economics, sociology, political science, and history, among others. Some countries, such as China, have kept long records of irrigation projects on turbid streams and flooding of sediment-laden rivers caused by levee breaches. These data are believed to be also useful in the modern studies of rivers.

Many international organizations, such as ICOLD, IAHR and IAHS among others, also direct attention to sediment problems. Some of them have even set up ad hoc divisions or committees in the area of sediment research. Understandably, however, the scope of these divisions or committees is often limited to the specific topics of interest in the individual organizations. To date, a truly comprehensive organization for promotion of sediment research, embracing most, if not all, of the relevant disciplines is still lacking. Its present status is thus contrary to the interdisciplinary nature of sediment problems and there is the urgent need to promote their studies. For this reason, the International Research and Training Center for Erosion and Sedimentation (IRTCES) hereby proposes a world organization to promote multidisciplinary sediment research. Emphasis is to be placed on the interdisciplinary nature of an organization needed to embrace all the disciplines listed above. It is believed that an organization of this nature can grow to the extent that it can benefit all countries through the sound progress of sediment research. This type of organization is definitely and urgently needed now and even more so in the coming years, if the sustainable development of the world economy is to be achieved. The proposed organization is aimed at uniting the world's scientists and engineers engaged in various fields of sediment research, thereby helping to solve all kinds of sediment problems in the world, using an interdisciplinary approach. An holistic effect on the advance of sediment research may be expected through mutual inspiration, when specialists in different disciplines come together.

The proposed organization is expected to cooperate closely with other related organizations, thus complementing rather than competing with them.

Possible Name of the Proposed Organization

The following name is tentatively suggested for the proposed organization.

World Association for Sedimentation and Erosion Research (WASER)

Please suggest another name as you wish.

Venue

IRTCES was founded in 1984, under the joint sponsorship of UNESCO and the Chinese Government, to promote research and training in solving scientific and engineering problems related to the erosion and deposition of sediment. Since then, it has organized many international training courses and workshops in fields pertaining to sediment research in the Asian-Pacific region. Its research activities are outlined and appended to this proposal. Its headquarters in Beijing comprises offices and conference rooms with modern communication and video-audio facilities and could serve as the base for the Secretariat of the proposed organization (thenceforth referred to as the Association).

Constitution and Bye-laws

A draft constitution of the association will be prepared and circulated for revision, provided that the present proposal is favorably accepted by the international community in sediment research. For the time being, it is suggested that an international ad hoc Council consisting of eminent scientists and scholars invited from all over the world would lead the Association. This Council in turn would elect the President and Secretariat of the Association from the Council members. The council under the general direction of the President would prepare bye-laws for divisions or committees under the Association with the assistance of the Secretariat.

Existing Series of International Symposia

Ever since its founding, IRTCES has served as the permanent Secretariat of the international series of Symposia on River Sedimentation. To date, eight such symposia have been held in China, U.S.A., Germany, India, Hong Kong and Egypt, respectively. The next one is scheduled to be held in 2004 at the site of the partially completed Three Gorges Project on the Yangtze River near Yichang, China. This series of symposia may be scaled up to serve as the official Symposium of the Association.

The Ministry of Water Resources of the People's Republic of China has kindly agreed to host the Symposium. It may be worth mentioning that the reservoir of this 18,200 Mw project has already been impounded to an elevation of 135 m with a depth of water at the dam of 125 m and has supplied its first power. Also the twin flights of 5 huge locks have been completed and are partially opened to shipping traffic. These locks will eventually enable 10,000 t tows to navigate through a total head of about 120m and sail over the dam. The normal pool behind the dam is to be at an elevation of 175 m.

Journal for the Proposed Organization

Since 1987, IRTCES has published the International Journal of Sediment Research, which is the only English-language journal that is devoted exclusively to the field of sediment research in the world. It is presently published quarterly and enjoys the support of many countries, leading in sediment research. This journal could become the official journal of the Association.

Membership

Members of the Association should be holders of degrees or diplomas in related disciplines from universities or colleges or their equivalents, and should be actively engaged or interested in soil erosion and sedimentation studies, including both research and engineering practice. Persons without the said degrees or diplomas but with appropriate practical experience may also apply for membership. A committee will be appointed by the President of the Association to consider all applications.

The annual membership fee for a regular member will be 30 US dollars with postage for surface mail included. This membership fee includes a subscription to the International Journal of Sediment Research, which is published quarterly.

All members are entitled to the reduced rates of registration when attending international meetings to be organized by the Association.

Appendix---Outline of Research Activities of IRTCES

In the field of research, IRTCES has cooperated with research institutions and universities in China and planned and coordinated the national studies of sediment problems for the huge Three Gorges Project on the Yangtze River of China since 1985. Many key sediment problems have been studied. A large programme of field studies costing hundreds of millions in RMB has been set up to collect field data after 2003 for the validation of the previous studies, including both physical and mathematical modelling. It also supervises fundamental studies of the changes in the yield of sediment as well as in runoff from the loess plateau region of the Yellow River basin resulting from extensive soil conservation work. For the regulation of the Lower Yellow River, which is a “perched” or above-the-ground river, it initiated the novel idea of diverting seawater to scour the estuary as a possible way to induce lowering of long reaches of the river.

IRTCES has organized the decade-long China-Germany cooperative research on unsteady transport of sediment. This project has been generously supported by VW-Foundation of Germany and National Science Foundation of China (NSFC). In addition, IRTCES has also organized the China-USA bilateral research cooperation on environmental sediment studies supported by US Science Foundation and National Science Foundation of China.

From 1989 to 1993, IRTCES, under the direction of the Beijing office of UNESCO, managed and completed a regional training programme on erosion and sedimentation for Asia, sponsored by UNDP. This programme was formally participation by 12 countries.

(Drafted by Bingnan Lin, Revised by D. E. Walling and Cheng-Lung Chen)

REFERENCE

Sundborg, A. and Rapp, A. 1986, Erosion and sedimentation by water: problems and prospects. AMBIO . , 1986.

P.O. Box 366, Beijing 100044, China, Fax: 86 + 10+ 6841 1174, E-mail: irtces@public.bta.net.cn