IDNDR-ESCAP Regional Meeting for Asia: Risk Reduction & Society in the 21st Century
Bangkok, 23-26 February 1999
Water Hazards, Resources and Management for Disaster Prevention:
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Not all countries providing information on damage caused by tropical cyclones or floods include a monetary assessment of damages. Information gleaned from other sources indicates that the costs of damage attributable to these two phenomena are increasing at a rate of over 4 percent annually. However, as these damage costs relate only to direct damage, they significantly underestimate the actual damage. If the value of the additional and significant indirect losses were included, the total monetary value would increase substantially.
Not all countries report on a regular basis or provide a complete set of statistics. As a result there are gaps in the chronology of damages presented for the countries concerned. Although questions have been raised as to the reliability of the data, the information does serve as a general indicator of the disruption caused by the damage inflicted by tropical cyclones, floods and droughts on the individual countries. An indication of the severity and frequency of disasters which accompany these events may be obtained from the tabulations.
In 1996, the Regional Office for Asia and the Pacific, United Nations Environment Programme summarized the root causes of environmental problems for the Asia and Pacific region in terms of social, economic, institutional and environmental factors. This summary also included detailed descriptions of the water-related hazards and accompanying disasters in the ESCAP region from the beginning of the International Decade for Natural Disaster Reduction in 1990. This information is presented in the following sections.
As we have seen, the developing countries in this region are situated in the world’s worst water-related hazard belts of floods, droughts, cyclones, tidal waves, and landslides. The major natural disasters faced periodically are largely due to climatic factors. The region has been one of the worst hit in terms of natural disasters, suffering 50 per cent of the world’s major emergencies. Since the International Decade for Natural Disaster Reduction began in 1990, the total number of deaths in the region due to these causes has exceeded 200,000, with the damage to property over this period estimated at US$100 billion. Vulnerability has increased due to growing urban populations, environmental degradation, and a lack of planning and preparedness.
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Disasters are the result of meteorological phenomena such as typhoons, hurricanes, sheet flooding, of coastal and river-based floods. These is turn appear to be related to climatic phenomenon such as the El Niño Southern Oscillation that results in a lower mean sea surface temperature in the east, failure of the monsoon rains in India, and drought in Indonesia and Australia. Vulnerability to natural hazards has been increased in many coastal areas as a consequence of the loss of habitat such as mangroves and coral reefs that formerly provided natural protection against coastal flooding.
Tropical cyclones, or typhoons, which are common in the ESCAP region, occur most frequently over the north-west Pacific during June and November just east of the Philippines, with an average of 30 typhoons per year. In the Bay of Bengal, tropical cyclones usually form over the southern end during April-December and then move to the east coast of India and Bangladesh, causing severe flooding and, often, devastating tidal surges. The cyclones generated in the South Pacific Ocean frequently cause devastation in small island countries such as Fiji, Tonga, Vanuatu, Solomon Islands, and Samoa. Overall, the Philippines, Bangladesh, and Vietnam appear to suffer most frequently from these large events.
Floods, which are the most common climate-related disasters in the region, include seasonal flooding, flash flooding, urban flooding due to inadequate drainage facilities, and floods associated with tidal events induced by typhoons in coastal areas. In Bangladesh, one of the most flood-prone countries in the region, as many as 80 million people are vulnerable to flooding each year. Another example is India, where 40 million hectares are at risk from flooding each year, and the average annual direct damage has been estimated at US$240 million, although this can exceed US$1.5 billion when flooding is severe.
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It has been observed that the impact of droughts differs widely between industrial and developing countries because of such factors as water supply efficiency and behavioural patterns such as water use efficiency. Most of the estimated 500 million rural poor in this region are subsistence farmers occupying mainly rainfed land. The drought-prone countries in this region are Afghanistan, Iran, Myanmar, Pakistan, Nepal, India, Sri Lanka, and parts of Bangladesh. In India about 33 per cent of the arable land, representing 14 per cent of the total land area of the country, is considered to be drought-prone, whilst a further 35 per cent can also be affected by drought when rainfall is exceptionally low for extended periods. Nepal has experienced severe droughts in the past, along with the Philippines, Thailand, Australia, and the Pacific islands of Fiji, Vanuatu, and Samoa.
Landslides, which are very common in the hills and mountainous parts of the region, occur frequently in India, China, Nepal, Thailand, and the Philippines. In addition to the primary cause - the topography - landslides are aggravated by human activities, such as deforestation, cultivation, and construction, which destabilize the already fragile slopes. For instance, as a result of combined actions of natural (mostly heavy rainfall) and human factors, as many as 12,000 landslides occur in Nepal each year.
Environmental degradation and disasters are very closely linked in this region. The countries that suffer most from disasters are the same ones in which environmental degradation is proceeding most rapidly. Similarly, poverty and vulnerability to disasters are closely linked. There is an average of some 3,000 deaths per event in low-income countries, compared with less than 400 per event in middle and high-income countries.
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Encroachment onto disaster-prone lands under the pressure of rapid population growth is accelerating the regional vulnerability to disasters. It has been estimated that annual flood losses in some countries are 40 times more today than what they were in the 1950s. According to the Indian Government, one out of every 20 people in the nation is vulnerable to flooding. Similarly, in China more than 85 per cent of the population is concentrated on alluvial plains or basins along river courses that constitute one third of its total land area.
A summary of major water-related disasters experienced in the Region is presented in Appendix 1 for the years 1994, 1995, 1996 and 1997. This information has been extracted from the July issues of ESCAP’s Water Resources Journal. The magnitude of each disaster is expressed in terms of:
A perusal of this damage information will verify that these disasters continue to wreak havoc throughout the region. The toll inflicted on its populations, in terms of human lives, individual suffering and hardship, is staggering in magnitude. Losses of private possessions and livelihoods, coupled with disruption to the normal pattern of life and local economies, can be spread over large areas and have a debilitating effect on the nation’s economy as a whole.
From the end of June,1998, persistent rains, which were attributed to the La Niña phenomenon, caused some of the most devastating floods of the Decade and took a heavy toll on human life and property in several countries in the ESCAP region. Although China and Bangladesh were the worst affected, the Republic of Korea, Viet Nam, India and Nepal also suffered significant loss of life and related damage. It was estimated that over 250 million people were affected by the floods with many being rendered homeless. A brief summary of the excessive rains and major floods in China, Bangladesh, Korea and Viet Nam are presented in the following sections.
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Flooding along some major rivers in China during August,1998 was described as the worst in decades.
The worst affected areas were in central and north-eastern China.
Commencing in June, heavy protracted rain fell over large areas of China and culminated in severe flooding on many major waterways, particularly the Yangtze River. It was estimated that the August peak was the second highest in more than 130 years, only being eclipsed by the record flood of 1954 when 33,000 people were drowned. In other parts of the country floods, landslides and mudflows affected some 240,000 people.
Over 3000 people lost their lives, with landslides and mudflows causing many of the deaths. Some 15 million people were rendered homeless, 5 million houses were destroyed and 22 million hectares were inundated and 1.8 million hectares of crops totally destroyed. The total damage bill was estimated to exceed $ US 20 billion.
Several major dykes were breached during the flood, affecting large sections of the local population. Many dykes were deliberately cut to ease the pressure on downstream areas. More than 500,000 people were evacuated from the flood diversion zone at Jingjiang on the Yangtze River so that the major dykes could be cut to protect the industrial city of Wuhan and other areas downstream.
It was necessary to mobilize more than 1.7 million Chinese soldiers and civilians to undertake essential maintenance work on the levees, which had to be undertaken to avoid failure as flood peaks threatened to overwhelm them. In some cases, the decision was made to abandon or breach some levees so that other more important areas could be protected. Essential services and relief efforts were taxed to the limit as essential services failed completely and medical services were placed under extreme pressure to cope with a situation of mounting disease outbreaks.
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Heavy monsoon rain which commenced to fall in mid-July 1998 caused extensive flooding in 37 of the 64 administrative districts, inundating about two thirds of the country. Major flooding was recorded in most rivers throughout these districts. The torrential rain which fell in the Himalayas caused rivers to break their banks, resulting in the longest-lasting floods in memory.
The floods resulted in the death of over 600 people who were drowned or killed by collapsing houses. Some 25 million people were affected by the floods and hundreds of thousands were left homeless. Over 6600 head of cattle were lost. A total of 760,000 hectares of farmland were inundated by floodwater with 425,000 hectares of crops being completely destroyed. The loss of crops was estimated at about US$ 150 million.
The Government launched a full-scale rescue and relief operation by mobilizing the army for emergency rescue operations and the distribution of food supplies to the flood victims. Many of the flood-affected communities suffered an outbreak of water-borne diseases resulting from contaminated drinking water.
During early August,1998 the City of Seoul experienced the worst flood disaster since the 1987 floods which claimed 381 lives, injured 428 and affected 151,000 people.
On the 5th and 6th of August. a storm deluged the metropolitan area of Seoul with 620 millimetres of rain, making it one of the heaviest downpours on record. The resulting floods and mudslides killed 131 people, left 61 missing and caused damage estimated at US$ 323 million.
Several days earlier, the same storm caused flash floods which killed 95 people, left 20,000 homeless and inundated 55,000 hectares of farmland. These floods were also accompanied by mudslides which engulfed buildings, damaged infrastructure and triggered an outbreak of disease.
Earlier in the year the northern parts of the country were ravaged by floodwaters. the heavy rains which started towards the end of July culminated in serious flooding, affecting a wide area. Some 270 people were killed, more than 150,000 people were evacuated and damage to property exceeded US$ 689 million. Over 47,000 hectares of farmland were swamped and large areas of the rice crop completely destroyed.
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Typhoon Dawn and other tropical storms which struck 15 central provinces of central Viet Nam from 11th to 26th November,1998 caused extensive flooding and damage. Flooding which accompanied the heavy rainfall resulted in flash flooding throughout the region and was reported to be the most devastating since the historical record flood of 1964.
Some 2.4 million people were directly affected by the disaster, 267 people being killed and more than 110 people being injured or reported missing. Almost 500,000 buildings were damaged by floodwater, some 10,000 of them being completely destroyed. Almost 115,000 ha of crops were inundated by floodwater and suffered significant damage. The total damage to crops, infrastructure and private property was estimated at US$ 93 million.
The devastation was exacerbated by the fact that most of the provinces had experienced serious drought conditions for 9 months prior to the onset of flooding.