Urban and environmental issues in East and Southeast Asian coastal lowlands

ENGiNEERiNG

GEOLOGY" ELSEVIER

Engineering Geology 37 (1994) 25-29

Urban and environmental issues in East and Southeast Asian coastal lowlands Jon L. Rau Natural Resources Division, Economic and Social Commission for Asia and the Pacific (ESCAP), Bangkok, Thailand (Revised version accepted October 20, 1993)

Abstract Rau, J.L., 1994. Urban and environmental issues in East and Southeast Asian coastal lowlands. In: E.F.Y. de Mulder (Editor), Engineering Geology of Quaternary deposits. Eng. Geol., 37: 25-29. Rapid progress has been made in the application of geologic principles for land use planning in large Asian cities and coastal areas, The rapid rate of growth of most Asian cities makes it imperative that geoscientists continue to develop thematic maps derived from basic geologic maps at appropriate scales for layman. More work needs to be done to make coastal zone managers more aware of the important contributions that geoscientists can make to the resolution of resource conflicts in the coastal zone. Thematic maps prepared by Geological Surveys for planners have proven useful in a number of countries in East and Southeast Asia. Effective programs for providing all types of geological information to planners have been developed in China, Malaysia, Indonesia and the Philippines. A number of countries in South Asia also have produced large-scale geological and thematic maps for land-use planners. Especially good progress has been made in Bangladesh, India and Pakistan. India has had an environmental geology programme for over 20 years and the Geological Survey of India has prepared thematic maps for planners in dozens of its larger cities. However, more should be done to show the usefulness of geologic data for planning decisions. Thematic maps prepared by geoscientists are not yet in widespread use in Asia. Geologic maps, for the most part, should be reinterpreted before they can be used by planners and decision makers. More research should be focused on what types of information planners need and how it should be transmitted to them by the Geological Survey. Planners and geologists continue to work in isolation in more than 50% of the Asian countries. Social and economic problems receive far more attention than single geologic events that can destroy a city in a few seconds and take the lives of tens of thousands of people. The author believes, and hopes, that by the year 2000 environmental and urban geology will be one of the highest priorities for Geological Surveys in the region.

1. Urban geology and coastal management issues Geoscientific data are becoming increasingly important for the assessment and m a n a g e m e n t o f complex u r b a n and coastal ecosystems. Geologic conditions such as structure, stratigraphy, geomorphology, natural hazards, geotechnical properties

o f subsoils and active geologic processes such as wave attack, tides, tidal currents, sediment transport, downslope movements, erosion and sedimentation all have a powerful impact on economic development, and if not properly understood, can seriously affect the viability o f projects, resulting in p o o r land-use decisions, resource-use conflicts,

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Jon L. Rau/Engineering Geology 37 (1994) 25-29

and environmentally unsound development. Urban development of coastal lowlands and deltaic areas has already resulted in major land-use problems stemming from a lack of understanding of basic geology, i.e., subsidence, salt water intrusion, coastal flooding, and coastal erosion. Large parts of the coastal areas in some countries are slowly submerging due to a combination of tectonic movement and sea-level rise. Deltas contain sensitive soft clays and thick peat deposits which invariably must be mapped carefully and require special types of development strategies for proper management. This report focuses on the progress of the application of geoscience for the development of ten Asian countries (i.e., Cambodia, China, Malaysia, Indonesia, Papua New Guinea, Philippines, Republic of Korea, Singapore, Thailand and Vietnam). These countries are collectively referred to here as the CCOP countries, because they are member countries officially linked by an intergovernmental body which has long been active in the study of Asian seas and coasts, the Committee for Coordination of Joint Prospecting for Mineral Resources in Asian Offshore Areas (CCOP). Geoscientists have not yet addressed the problems of coastal zone management, hitherto considered the responsibility of environmental agencies. Moreover, geoscientists have not been able to provide their data in a useful form for decision makers, and the basic geologic framework of most critical coastal zones or environmentally sensitive ecosystems is poorly understood and frequently ignored by planners. Geologic conditions and terrestrial/marine processes need to be understood in advance of development to avoid degradation of the urban and coastal environment and to properly evaluate the potential impact of man on coastal ecosystems. Since 1985, the Economic and Social Commission for Asia and the Pacific (ESCAP) has encouraged countries of this region to apply geological principles in land use planning and development. A number of workshops, seminars and training courses were organized around the theme of urban geology and more than 100 papers on the urban geology of Asia were published in the ESCAP Atlas of Urban Geology series. Some of the most remarkable results have been

obtained in CCOP countries. Large-scale mapping is now being performed in many urban and coastal areas of Asia and the Pacific. Nevertheless, more progress is needed to ensure that the principles of geology and especially the knowledge of geologic processes and natural hazards be taken into consideration by planners in selecting land use options. Geoscientific disciplines, including oceanography, geology, geophysics and related coastal engineering and geotechnical disciplines are essential in resolving the dichotomy existing between environmental quality and sustaining economic development. East Asian Seas embrace some of the most rapidly industrializing countries of Asia and the Pacific. It is useful to review the context of the use of geologic knowledge to resolve the present coastal zone issues in the region. East Asian Seas and their associated coastal areas link the countries of Southeast and East Asia. The mineral and hydrocarbon resources of these areas have been the focus of exploration activities for more than 50 years. The Seas and their adjacent land areas form a critically important interface between the Pacific and the Indian Oceans and are characterized by extensive high diversity ecosystems, both terrestrial and marine. The richness of the natural living resources is supported by a warm tropical climate and ocean currents, as well as by abundant precipitation, especially in the area south of latitude 30 ° N. The countries bordering the East Asian Seas have an extensive combined length of coastline of more than 150,000 km. East and Southeast Asian countries had a mid-1989 population of 1.7 billion (China's population was 1.1 billion) and a projected population in 2010 of 2.1 billion. In these countries urban and coastal development is rapid with approximately 75% of the current population living in coastal cities and towns. Some of Asia's largest cities are located on deltaic plains of East and Southeast Asia (Bangkok, Kobe, Manila, Nagasaki, Osaka, Fushou, Guangzhou, Hangzhou, Hanoi, Ho-Chi-Minh City, Jakarta, Pusan, Shanghai, Seoul, Shenyang, Singapore, Surabaya, Tianjin, Tokyo and Yokohama). If the geologic environments of these coastal cities were examined, it would be noted that many of the cities have a similar physical setting, and

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hence, share such problems as extensive and poorly drained backswamps, soft clays, thick peat deposits, salt-water intrusion, clogged rivers and distributary systems, unstable river banks, extensive flooding and subjection to periodic typhoons, tropical cyclones and tsunamis. A few areas are periodically subjected to devastating earthquakes (China, Indonesia, Philippines). In addition to the general problems associated with low-lying lands near the sea, many of these cities have overexploited their groundwater, resulting in subsidence and loss of a supply of potable water. The cities of Asia continue to experience explosive growth and, subsequently, have outpaced any plans that were originally made. In almost every case their development has proceeded with a virtual ignorance of the geologic conditions. The urban and coastal zones of these regions are heavily utilized to support a broad range of socio-economic activities such as industry, transport and commerce, recreation, farming, etc. With this development a great strain has been placed on the coastal environment. Mariculture and coastal aquaculture development is extensive and growing within the region with ongoing conversion of mangrove forests into aquaculture ponds. Tourism, particularly coastal tourism, plays an important role in the economy of most of these countries and unexploited coastal areas are continually being developed for this purpose. The dependence of these regions on the sea is evident from the average annual marine catch which has been increasing steadily. However, two major fishing areas, the Gulf of Thailand and the Strait of Malacca, already have been overfished or polluted by urban discharge. The fishery of Southeast Asian countries has contributed 11% (about 6000 metric tons in 1985) of the world's marine catch. The value of the catch has increased about 38% since 1975 (these data exclude the catch from China and Japan). Forestry resources of the coastal regions are far less important than they were twenty years ago, however, the countries of Southeast Asia are still major suppliers of rice, coffee, tea, sugar, spices, rubber and palm oil. Mineral resources are especially important in the coastal areas of Indonesia, Malaysia, Thai-

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land and, to a lesser extent, China, Japan, the Philippines and Papua New Guinea. The most important mineral mined in the coastal and nearshore area is cassiterite but the region is characterized by other mineral sands of economic importance including zircon, monazite, rutile, ilmenite and gold. Rich deposits of gemstones are found in near-shore and coastal areas of several countries. East and Southeast Asia are characterized by large rivers which have built more than a dozen large deltas into the South China Sea. These deltas and their offshore extensions have been highly productive with respect to oil and gas. Indonesia is the leading producer of natural gas in the region and remains the world's largest exporter of LNG. Indonesia's natural gas production in 1990 was 41 __+1012m3. Production of natural gas in China was increased steadily over the period 1985-1990. Natural gas production in China was 14.7 × 1012m3 in 1990. Natural gas production in Malaysia has increased sharply from the start of gas production from eastern Malaysia in 1983 and totalled 40× 1012m3 in 1990. Thailand is a major gas producer and sales rose to a record level of 5 × 10X2m3 in 1987. In Papua New Guinea the Hides gasfield was being developed rapidly and an 11-km pipeline from the top of Hides mountain to a power station at the Porgera gold mine was under construction in 1991. The Philippines has little gas production at present, but produced more than 660,000 tons of oil in 1990. Offshore and coastal areas of Cambodia and Viet Nam are expected to become important producers in the years ahead. Many important oil and gas fields are located in the lowland areas of Southeast Asia or occur only a few kilometres offshore. The Asia-Pacific proven natural gas reserves of 370.8 trillion cubic feet (Tcf) are approximately 8.75% of the World total proven gas reserves. Oil production from the CCOP member states reached a level of about 200,000,000 tons in 1987, about 8% of the World production. CCOP has considerable expertise with regard to the assessment of mineral and hydrocarbon resources in coastal and nearshore waters. Any plan for sustainable development must take into consideration the continuing efficient exploitation of these resources. Professional staffs of many

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Asian countries have a sound basic knowledge of resource issues which are important to coastal development plans and their input should be reflected in national and regional coastal management discussions and planning. Presently, there is an opportunity to capitalize on their geological expertise and to improve their capabilities to manage coastal and near-shore mineral and hydrocarbon exploitation while retaining the values of natural coastal and marine ecosystems. During the last decade, many Asian countries have also developed excellent capabilities to study Quaternary sediments which blanket most of the coastal areas of the region. Knowledge of these deposits is considered especially important in providing technical input to coastal management planning. Shallow geologic conditions (up to depths of 100 m) in and around the coastal lowlands and deltas of the region are best surveyed using methods already in practise. However, the application of these methods and techniques has not yet resulted in a comprehensive, large-scale mapping of critical areas of the coastal zone. Deltaic deposits are, in general, poorly known and rarely mapped at adequate scales to provide the necessary input to national and regional development plans. For example, in parts of the coastal lowlands of Thailand, Malaysia and Indonesia, development is spreading into areas in which the subsoils contain thick sequences of unconsolidated sediments including peat deposits. In these areas the development is normally accompanied by drainage of the peatlands resulting in compression of as much as 3 m. Structures built on such deposits are eventually damaged and frequently have to be abandoned. The geology of important transportation routes and related infrastructure is becoming extremely important, especially with regard to the use of rivers in deltaic areas, and public works departments are now recognizing that geological input is necessary for the planning of highway routes, ports, harbours, bays and lagoons, as well as in keeping open the major river arteries frequently clogged by silt. The development of coastal roads and waterways which are essential for transport and access to inland ports has reached a critical stage. The large sediment loads of Asian rivers has resulted

in sedimentation in parts of the river distributary system and actually closes some river channels during part of the year in the Mekong delta. The river improvement required has necessitated large expenditures for dredging, construction of river structures, bank protection and the setting up of a comprehensive navigation system. The maintenance of navigable channels in rivers of unstable regime is increasing and the cost of transport is increasing. Consequently, the planning of rivers and port development depends on adequate knowledge of geologic processes, especially erosion and sedimentation, both within the river/distributary system and along the coastline. Such considerations are of primary importance in the management of delta ecosystems in such countries as China, Malaysia, Thailand, Indonesia, Philippines and Viet Nam. Engineering considerations are equally important. The ecosystems in which engineering data are of prime importance in management decisions are the following: river estuary, river mouth, beach, coastal lagoon, offshore bar, coral reef and coastal waterways. Coastal geology and engineering data are necessary inputs to develop an infrastructure in these ecosystems. Coastal engineers are frequently attached to public work departments but need to coordinate their activities closely with national geological agencies that have the responsibility of mapping and monitoring active geologic processes in coastal environments. Consequently, a high value should be placed on strengthening mechanisms for cooperation between coastal engineers and geoscientists, so that their joint input is utilized in development planning of the coastal zone and in the management of natural resources therein. Coastal engineering includes ports, harbours, wharves, jetties and breakwater structures, urban waterfront and estuarine development, marinas, ocean outfalls, cooling structures and dredging operations. Ocean engineering includes offshore platforms, offshore structures, submarine pipelines, ocean energy stations, buoy technology, navigational aids such as beacons and lighthouses and marine cities. Coastal zone management should include the knowledge of the impact of these structures on natural resources. Their developmen-

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tal and operational aspects, especially with regard to siting and construction, are normally preceeded by a geological investigation and an assessment of geotechnical conditions of the subsoil at the site. Consequently, geologists have the responsibility of indicating, at an early stage, any adverse impacts associated with the concerned engineering projects. They have a better chance to provide a 'control' mechanism on environmentally unsound planning by indicating the possible problems well in advance of development. Geoscientists can provide the data required to ensure that projects are actually built in harmony with nature, rather than degrading coastal ecosystems. One approach is to bring geologists and coastal engineers into the planning process because of their important role in providing basic data from coastal and marine surveys.

2. National strategies Most governments recognize the potential use of geoscience information for land-use planning but this has rarely been a priority for governments. The traditional goals of geological surveys and mining agencies have been to provide information on mineral and hydrocarbon potential for national planning and development. However, the reorientation of emphasis of national development plans now includes a significant component related to the application of the geologic knowledge of landuse planning. What has been lacking is a decision by governments to reorient more of the work of geological surveys so as to sharply increase their outputs with regard to environmental geology and the provision of geologic data to various other government agencies on a regular and systematic basis. This has taken place to a limited extent in a few geological surveys in the region, namely, in Bangladesh, China, India, Indonesia, Malaysia,

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Republic of Korea, Pakistan and the Philippines. In fact, in Malaysia a separate section of the Geological Survey handles the dissemination of appropriate maps and geologic data to city engineers and planners, as well as to regional planning bodies. In some countries public work departments, town planners and construction ministries are much more aware of the importance of including geologic data in their basic framework for managing the development of natural resources, the environment and, specifically, in mitigating the impact of man's development on the coastal zone. There is also much more interest in these issues in Thailand, the Philippines and Singapore. Viet Nam recognizes that geoscientific data are necessary in order to manage the development and to monitor geologic processes related to estuaries and deltaic influences in the Mekong delta. Likewise, its northern delta at the mouth of the Red River is one of the most densely populated areas in the world. Its proper management is essential to sustaining rural development there. Likewise, countries such as Cambodia, the Philippines, Indonesia, Malaysia, the Republic of Korea, Papua New Guinea, Singapore and Thailand are engaged in expansion of port facilities and rely heavily on efficient access to these areas and on the maintenance of sea lanes and coastal waterways to provide access to trading partners. Consequently, marine processes have been of concern to them but have rarely been formally considered in national coastal management plans - - certainly not as input to be derived from a national geological/mining agency. This is now changing and most states have marine geology survey divisions within national geological institutions or as separate institutes. These agencies are capable of undertaking the special surveys required for coastal management studies. The Geological Surveys of the region may well play a leading role in coastal and urban zone management by the year 2000.