Water Hazards, Resources and Management for Disaster Prevention:
A Review of the Asian Conditions
IDNDR 1991-1999

To date, the principal thrust of the water-related disaster mitigation strategies employed in the ESCAP Region has concentrated on disaster preparedness, rather than on disaster prevention. Whilst this approach has in many countries been successful in reducing the overall death toll associated with these hazards, the amount of physical damage has continued to mount.

The prevention measures which can be directed towards the reduction of the effects of the hazard prior to its occurrence and the preparedness measures which may be implemented during and after the disaster have been described in detail in Chapter 4.

In summary, these mitigation measures attempt to lessen the impact of the hazard by adopting both structural and non-structural approaches. The objective of the structural approach is to control the effects of the hazard by using specific engineering works as the best means of protecting life and property. On the other hand, the objective of the non-structural approach is to modify susceptibility to the hazard through a range of controls and other non-engineering devices.

The most successful preventive measures employed to curb the destructive and injurious effects of tropical cyclones are building design and construction standards, established to assist buildings and other structures to resist wind and water damage. The range of measures available for protection against the effects of flooding is much wider than that available to reduce the impact of tropical cyclones. It includes civil engineering-oriented structural measures, such as channel modifications, flood storages and levees, as well as non-structural measures such as planning controls and flood proofing of buildings. These measures are designed and implemented in order to reduce the incidence or extent of flooding and storm surges and/or to minimize their effects.

The selection of the best mix of measures for application at a given location to prevent the occurrence of future water-related disasters should be based on a consideration of all the available structural and non-structural options. The optimal mix of measures should be based on risk analysis (see Chapter 7) and the economic performance of the overall scheme. Consideration of social and environmental factors in addition to the legislative and legal constraints should form part of the planning process.

Disaster preparedness covers those actions that are taken when a potentially hazardous event threatens to become a disaster. Preparedness activities are designed to reduce social disruption and losses to existing property and are an essential component of overall disaster planning. Although these activities can serve, in the absence of more permanent mitigation measures, to reduce the threat to loss of life and property, they are more effective when employed as a component of a comprehensive, overall disaster management plan.

Because China is frequently struck by the full range of water-related hazards, it experiences massive disasters in terms both of human suffering and of economic losses, often over wide areas. Accordingly, the Chinese Government attaches great importance to its efforts to reduce the effects of these disasters.

Its approach to mitigating these catastrophes involves the principle of comprehensive disaster management, which combines economic development with disaster reduction and includes such measures as disaster prevention, fighting, relief and rehabilitation in promoting social stability and protecting life and property.

Over the last two decades, and with increased vigour during the IDNDR, China has made a concerted effort to improve the management functions required to ensure a fully integrated and efficient natural disaster reduction system, which is tailored to meet China’s own special needs. This has involved the promulgation and enforcement of a suite of appropriate laws and regulations; the vertical and horizontal integration of relevant government departments according to their respective fields of competence; the application of engineering and non-engineering measures; the raising of public awareness; improved hazard monitoring and early warning systems; the formulation of disaster control plans based on risk assessment; the application of science and technology in mitigating disasters; increased education and training in natural disaster reduction; and the fostering of the growth of disaster reduction NGOs.

Because China experiences meteorological disasters in the form of tropical cyclones, floods and droughts, which can affect huge populations and vast areas, its disaster mitigation efforts have concentrated largely on the management of these three hazards.

China is exposed to severe and frequent tropical cyclones, torrential rains and drought. The Chinese Government is concentrating its efforts to combat these disasters and improved levels of prediction and warning are constantly being implemented in an attempt to contain the destruction and economic loss associated with such disasters.

The 1998 flood in the Yangtze River was as great as those of 1931 and 1954, but the resulting flood damage was much less than that experienced during the earlier floods. For example, the area inundated by floodwater during the 1998 flood was insignificant compared to the extent of flooding in the 1931 flood, which covered most of the middle and lower Yangtze region, and the 1954 flood, which inundated about 3.2 million hectares. In the 1931 flood 145,000 people died; some 33,000 people died in the 1954 flood; but only 1562 people were killed in the 1998 flood, most by debris flows in mountain regions.

It is obvious from the achievements in disaster mitigation by the Chinese Government that the reduction in flood-related deaths and damages can be directly attributable to the flood control systems which have been implemented in both rural and urban areas. Although the main thrust of China’s flood management has been directed towards structural measures, including levees, reservoirs, flood diversion basins, and river training and dredging, non-structural measures such as catchment management and rehabilitation techniques are progressively being employed as a significant component of an integrated flood management system.

Disaster preparedness is designed to minimize loss of life and property damage and to organize and facilitate timely and effective rescue and relief in the case of a disaster. It must be supported by legislation which can ensue readiness to cope with disaster situations when they cannot be avoided. It also includes forecasting and warning, the education and training of the population, and organization for and the management of disaster situations, including the preparation of operational plans, training of relief groups, stockpiling of supplies and provision of necessary funds. Furthermore, it should include flood fighting and evacuation, relief and rehabilitation. To be effective, such disaster preparedness measures, including those which are taken when the occurrence of a tropical cyclone, flood or storm surge imposes the threat of a disaster, must be planned in advance.

The most important of these measures for helping to mitigate the effects of tropical cyclones and floods is the development and implementation of effective forecasting and warning systems. These can be particularly effective in reducing the potential damage by increasing the time between the prediction and onset of an event. To be effective they must include not only the latest techniques for the formulation of accurate forecasts, but also related communications systems designed to disseminate timely and accurate advice to the general public.

As part of its contribution to the mid-term review of the IDNDR Programme, the Water Resources Section Secretariat of ESCAP prepared an overview of the status of the natural disaster mitigation efforts of its members. It found that there has been a growing recognition in the region of the significant benefits of disaster prevention and mitigation, rather than ad hoc relief reduction activities. Some countries had a long-established framework for responding to the disaster mitigation requirements of the country. Others had either strengthened their institutional mechanisms or were in the process of overhauling them.

Substantial progress had been achieved in meteorological forecasting and warning of tropical cyclones, and the capability to forecast floods had improved considerably through the individual efforts of various countries, with assistance from the support given by ESCAP, the World Meteorological Organization (WMO), UNDP and other organizations. Useful programmes and the capability to forecast tropical cyclones and floods had improved considerably through the establishment of the Typhoon Committee and the Panel on Tropical Cyclones. These two bodies had cooperated in the forecasting and warning of cyclones, information exchange, provision of training and other forms of activity relating to the reduction of the impact of water-related natural disasters (see below).

The development and use of radar for forecasting and measuring rainfall events and the increased number of telemetric rainfall stations in some countries had increased their capability for the rapid collection and processing of precipitation data and the forecasting of floods. There was still considerable variation among countries of the region with regard to the availability and reliability of equipment needed for effective cyclone and flood forecasting and warning. Prediction of drought had also become more reliable by taking into account such factors as the El Niño phenomenon and the undertaking of appropriate mitigation and preparedness measures.

It was determined that each country needed to improve the quality of forecasts and warnings in relation to water-related natural hazards and to increase the lead time of warnings, to enable areas likely to be affected to make adequate advance preparations. The need for emphasis to be given to the improvement of communication links for the transmission of basic data and providing related warning information about natural hazards was seen to be a priority issue.

Risk assessment and mapping had not been undertaken by most of the countries of the region. There was a need for comprehensive vulnerability analysis to be undertaken for disaster-prone areas, incorporating information about past disaster events, the socio-economic conditions of the population living in the affected area, and inventories of major structures liable to damage. Risk assessment and hazard mapping would then be used to delineate areas vulnerable to natural hazards and determine the frequency, intensity, impact, return period and other data in relation to each category of hazard.

Almost all countries in the Asian and Pacific region experienced severe flood problems at comparatively frequent intervals. Their traditional approach to the reduction of flood losses relied upon the use of structural flood mitigation measures such as the construction of dams, levees and channel improvements. Most of the earlier flood mitigation programmes adopted by individual countries had been specific to a city or to a discrete agricultural area and had employed a narrow range of engineering works to provide solutions to the flooding problem. Although some projects were successful, some of them have actually exacerbated flood damage. In recent years, most countries have recognized the inadequacy of programmes based solely on structural measures. Numerous attempts had been made to employ non-structural flood loss prevention measures to assist in minimizing losses, principally through exercising control over development in flood-prone areas. These measures were usually associated with a mix of structural measures and, in some circumstances, provided a comprehensive means of coping with a flood problem. In many cases, however, attempts to formulate programmes which included some non-structural measures had met with limited success, particularly those involving planning controls, acquisition of land and the relocation of people.

Bangladesh is predominantly a rural country, relying heavily upon agricultural production for its existence. Unfortunately, its topographic and climatic systems make it one of the most water-related disaster prone countries in the Asian region. It is frequently struck by destructive cyclones, devastating floods and crippling droughts. These hazards cause severe agricultural losses and place great strains on country’s economy and its ability to achieve sustainable development.

Cyclones frequently sweep out of the Bay of Bengal and impact on the coastline with devastating effects. These cyclones generate dangerous floods, which are exacerbated by storm tides and wreak havoc along the entire coastal belt. Further upstream, in the delta formed by the three great rivers, the Padma, the Jamuna and the Meghna, frequent major flooding can inundate up to 70 percent of the entire country. The effects of these floods in terms of loss of life and property, ecological damage and lost production have crippled the country’s economy and set back development programmes by years. In addition to the loss of production caused by cyclones and floods, Bangladesh has also experienced severe drought conditions which have resulted in disastrous crop failures. The loss of agricultural production caused by droughts has also imposed significant strains on the socio-economic structure of the country.

In order to combat the many major disasters which have afflicted Bangladesh in recent years, the government has pursued a vigorous programme of disaster management. This programme gave the initial priority to improvement in the forecasting and early warning systems for cyclones and floods, along with emphasis on emergency response and relief. Subsequent initiatives have involved prevention and preparedness measures with a bias towards infrastructure development, such as the construction of coastal dykes and river embankments. More recently, multi-level initiatives are being pursued which include: awareness and education programmes; decentralized planning and community participation in disaster mitigation and response; involvement of NGOs in disaster mitigation and response; and incorporation of disaster management and reduction component in development projects.

Up to the present time, the disaster management programme has been successful in mitigating the effects of water-related natural disasters. For example, the severe 1991 cyclone resulted in the death of 140,000 people and property losses of US$ 2.0 billion. A cyclone of similar intensity to the 1991 event occurred in 1993 and resulted in the loss of only 126 lives. The reduction in the death toll was directly attributable to the improved forecasting and warning services and the provision of cyclone shelters. Although the 1998 flood was the worst in living memory and inundated more than 70 percent of the entire country, the limited number of casualties compared to earlier floods was also attributable to the effectiveness of the disaster management measures implemented over time.

Bangladesh is aware that although the comprehensive control of water-related natural hazards is not entirely possible and the population will have to continue to live with the associated disasters which they bring, continuing effort is required in the development of a national disaster management plan to ameliorate their future impact.

Adequately constructed and equipped cyclone shelters had considerably reduced the number of lives lost to typhoons and tropical cyclones. As a preventive measure, cyclone-resistant designs for dwellings had helped reduce the number of casualties and reduce serious damage to buildings. Progress had been achieved in developing mitigation measures to improve the safety of non-engineered structures such as ordinary dwellings and simple public buildings constructed with local materials in the traditional manner. In some countries of the region there was a need for preparation or review of cyclone resistant design codes for buildings and other engineering structures and for their enforcement, as well as the undertaking of proper arrangements for the infrastructure to be able to deal with natural hazards.

SUCCESS STORY - REPUBLIC OF KOREA

The Republic of Korea frequently suffers disasters resulting from tropical cyclones, storms and floods. Over the last 20 years, these hazards have caused considerable loss of life, disruption to the economy and massive property damage. Occasional droughts also affect the agricultural and industrial sectors and impact upon rural communities.

A review of the available damage statistics discloses that the Government’s efforts in natural disaster reduction has resulted in a dramatic reduction in the death toll. During the IDNDR the average annual loss of life has been reduced from 280 to less than 80. However, the average annual damages have remained substantially constant over the same period.

These achievements can be attributed to improved disaster management planning and the initiatives associated with the plan. The most significant initiatives have involved the following: a strengthening of the institutional framework for natural disaster prevention and preparedness by concentrating the overall responsibility for the task into a single agency; a comprehensive revision of the Natural Disaster Countermeasures Act to incorporate comprehensive disaster prevention measures, provision of adequate funding for operational aspects and the encouragement of private participation in disaster mitigation; the placing of greater emphasis on scientific research in the field of disaster prevention; and the formulation of a 5-year Disaster Prevention Plan directed towards the implementation of measures covering afforestation, flood control, disaster prevention and technology development.

To cope with the fact that disasters are becoming more varied and larger in scale, the Korean Government is continuing its efforts in the field of disaster reduction by concentrating on such aspects as: streamlining land development regulations; availability of flood insurance; greater investment in flood control; systematic scientific research for disaster prevention; development of a national disaster management system; and active international cooperation.

Most countries of the region had enacted legislation to provide for the controls and responsibilities necessary to cope with disaster situations. This legislation has permitted the relevant authorities to govern the long-term requirements of disaster prevention and the short-term needs of disaster preparedness. Although statutory controls were available to govern the relevant aspects of community planning and development, including zoning, subdivision controls and environmental issues pertaining to disaster prevention, many Governments were reluctant to invoke them. Many Governments had appointed a central organization to coordinate the disaster mitigation activities of the various government bodies and other interested groups, so that a comprehensive approach was adopted. In certain countries, some of these organizations were established on an ad hoc basis only when a natural disaster had occurred or was expected to happen. It was only the more developed countries of the region that had cohesive institutional arrangements in place.

Most countries had upgraded their civil defence capability for the rescue of people from endangered areas, through the mobilization of armed forces or the organization of the local community in response to threats of disaster through cooperative activities involving volunteers. A number of countries had introduced programmes to provide information and educate the public on hazard situations, particularly floods.

The Typhoon Committee was established by the participating countries under the auspices of ESCAP and WMO and has been functioning and holding annual sessions since 1968. The Typhoon Committee covered a wide range of activities on typhoon-related disaster reduction for which several important initiatives were launched under its framework, particularly those aiming at improving typhoon and flood forecasts. Among the initiatives undertaken, the two most important ones were the Typhoon Operational Experiment (TOPEX) programme and the SPECTRUM (Special Experiment Concerning Typhoon Recurvature and Unusual Movement) which laid down important infrastructure and established human resources and facilities for subsequent contribution to disaster prevention and preparedness. It may be noted that the objective of TOPEX was to carry out, through international co-operation in the prompt and reliable collection and exchange of observational data, an operational test of the functioning of the various systems used for typhoon analysis, forecasting and warning. TOPEX consisted of three components the meteorological hydrological and warning dissemination and information exchange components. TOPEX was an exercise that tested the effectiveness of the totality of the system built up over more than a decade for flood warnings, typhoon warnings and dissemination of information to the public. For flood loss prevention, the Committee had carried out the following activities:

1. evaluation of the established system for forecasting and warning of the hydrological effects of floods and/or storm surges by comparison of their outputs with actual observed data in the fields;

1. identification of simple deterministic forecasting models used by, or available to services in the typhoon area, selection of specific models for application to each designated area and comparison of the models' results in real-time forecasting operational mode;

1. evaluation of separate and/or combined hydrological effects of typhoons, particularly river and storm surge flooding, and thereby determination of associated flood risk.

In parallel, other regular activities have been in operation include:

1. operation, maintenance and improvement of existing flood forecasting and warning systems;
2. establishment of flood forecasting and warning systems in other river basins;
3. establishment of pilot areas for comprehensive flood loss prevention and management which included investigation, survey and study of the pilot areas, preparation of comprehensive plans for flood loss prevention and management within the context of overall water resources development of the pilot areas and implementation of selected aspects of the comprehensive plans by stages, if necessary.

In terms of activities for disaster preparedness, the Committee provided assistance in establishment of appropriate national organizations at all levels, and in formulation of plans; improvement of facilities and services for emergency communications; improvement of effectiveness of warnings and community reaction; training in disaster preparedness; improvement of techniques for assessment and reporting of damage and consequent needs; preparation and implementation of pilot projects for pre-disaster planning, including analysis of hazards and resources at all levels, and case studies on such plans and their effectiveness in practice; and development of measures to reduce damage associated with storm surge.

The advent of IDNDR has strengthened the cooperation among the Committee members and also helped enhance awareness on the importance of natural disaster reduction. The membership of the Committee continued to increase from 7 to lately 15, consisting of the Governments of Cambodia, China, Democratic People’s Republic of Korea, Indonesia, Japan, Lao People’s Democratic Republic, Malaysia, Macau, Philippines, Republic of Korea, Singapore, Thailand, United States, Viet Nam and Hong Kong, China.

In parallel with the operations of the Typhoon Committee, the Panel on Tropical Cyclones was also established under the auspices of WMO and ESCAP to promote measures to improve tropical cyclone warning systems in the Bay of Bengal and the Arabian Sea. The Panel aims to direct their common endeavours towards successful implementation of a comprehensive cyclone operational plan to facilitate the most effective tropical cyclone warning system for the region with existing facilities.

As part of the common endeavour, the Panel adopted a comprehensive cyclone operational plan for this subregion. The basic purpose of the operational plan was to facilitate the most effective tropical cyclone warning system for the region with existing facilities. In doing so the plan defined the sharing of responsibilities among Panel countries for the various segments of the system and records the co-ordination and co-operation achieved. The plan recorded the agreed arrangements for standardization of operational procedures, efficient exchange of various data related to tropical cyclone warnings, issue of cyclone advisories from a central location having the required facilities for this purpose, archival of data and issue of a tropical weather outlook for the benefit of the region.

The operational plan contains an explicit formulation of the procedures adopted in the Bay of Bengal and Arabian Sea region for the preparation, distribution and exchange of information and warnings pertaining to tropical cyclones. Experience has shown that it is of great advantage to have an explicit statement of the regional procedures to be followed in the event of a cyclone, and this document is designed to serve as a valuable source of information always available for reference by the forecaster and other users, particularly under operational conditions.

A technical plan aiming at the development and improvement of the cyclone warning system of the region has been drawn up by the Panel. Implementation of some items under the technical plan would lead to a strengthening of the operational plan. The operational plan is evolutionary in nature. It is intended that the text of the plan be updated or revised from time to time by the Panel and that each item of information given in the annexes to the plan be kept up to date by the member country concerned. The plan included a hydrological programme comprising two main components:

1. hydrological network and flood forecasting systems, and
2. storm surge project.

Cooperation among the members continues to be strengthened with the implementation of these components in addition to work on meteorology. An important point to note in this respect is that through the implementation of the plan, the exchange of hydrological data among the member countries for flood warnings has been greatly improved.

In many countries of the region it was recognized that the initial and most vital response to a disaster must be at the local level and that the community must be well informed about disaster-preparedness measures and be alert in the time of disaster. It was considered essential that the building of disaster awareness in the general population, starting with the individual, was essential in reducing casualties. In order to promote community involvement in disaster prevention and preparedness, community awareness programmes and educational programmes relating to warning systems and other aspects of disaster preparedness were developed and implemented, and committees that included representatives of non-governmental organizations and the public were established at the local level to monitor and guide disaster-relief operations.

The main water-related disasters affecting India are tropical cyclones, floods and droughts. Although the incidence of cyclone strikes in the coastal belt is not high, India is regarded as one of the most flood prone countries in the region, with 40 million hectares, or 12 percent of the whole country, being affected. India is also often subject to drought when the monsoon rains fail to occur.

India is a union of 25 States and 7 Union Territories. The Union Territories are subject to the direct rule-making powers of the National Parliament and the administrative control of the Central Government. The States are fully autonomous in relation to their activities under the Constitution.

The responsibility for natural disaster management is spread over the various tiers of Government, with State Governments assuming a primary role in disaster rescue and relief measures. The Central Government supplements the States’ activities by providing substantial financial support and other forms of assistance.

In recent times many advances have been made in disaster mitigation, response and preparedness. Major advances have been achieved in the field of disaster response at both the Central and State Government level through closer collaboration among the various agencies. Overall coordination has been assumed by the Ministry of Agriculture with support from other relevant ministries. Streamlining the disbursement of relief funds following a disaster has substantially improved the relief operations and reduced hardship.

Improvement in cyclone forecasting and warning has been made possible by the use of remote sensing systems, including satellite and weather radars. Timely warnings and quick response has permitted the early evacuation of threatened populations. As a consequence, the number of cyclone related deaths has been reduced by a factor of 10.

Flood modification strategies include both structural and non-structural measures. The construction of numerous dams, drainage channels and protective embankments along rivers has helped to mitigate the intensity of floods and reduce damage in many areas. The non-structural measures include risk mapping, flood plain zoning and forecasting and warning. The flood forecasting and warning functions are the responsibility of the Central Government, which has established a comprehensive network throughout the country. Watershed management has been elevated in importance to further reduce run-off and promote sustainable development.

Drought monitoring and alleviation is also afforded a high priority in disaster management. The construction of water storages, monitoring of crop situations and the implementation of drought management strategies has helped to ameliorate the effect of drought and to reduce the amount of associated damage.

In an effort to further its achievements in water-related disaster reduction, India is directing its efforts towards the linking of disaster mitigation with development planning, the establishment of more effective communication systems, the use of the latest information technology, the introduction of disaster insurance, the employment of extensive public awareness and education campaigns, particularly in rural areas, the greater involvement of the private sector, and the strengthening of institutional mechanisms and international cooperation.

Last Section   Back to top   Next Section