The typhoon season is fast approaching and many people in Taiwan are wondering whether they will be flooded out again this year. Flooding is a perennial problem in Taiwan which causes great economic losses and inconvenience. Taipei, the provisional capital of the Republic of China is often inundated at this time of the year, but the government is moving towards a solution of the costly problem.

Taiwan's climate and geography are to a large extent responsible for floods. Located in the sub-tropical zone, the island is often afflicted by typhoons which bring huge amounts of precipitation in a short time. Taiwan is mountainous, and the Central Mountain Range dividing the island from north to south is the catchment area for most of Taiwan's short but fast-flowing rivers. Most of the year, these rivers have little water, but when the rains start, they become raging torrents. Silt carried in the water raises river beds, making floods even more likely.

These are just a few of the natural causes of floods, but man has created several of his own too. Over the years, uncontrolled logging, construction work on hillsides and the removal of sand and stones from river banks, have all depleted natural drainage and changed river courses.

The Taipei Basin is particularly prone to flooding. Three rivers flowing through the basin have their confluence in the Tamshui estuary which is too narrow to take all the water that accumulates during a typhoon.

The basin was a swamp just over a hundred years ago, but the gradual accumulation of sand and silt carried by the rivers filled in the marshes, making it possible for the city to be built. During the Ching dynasty, Taipei became the capital of Taiwan Province and it remained so through 50 years of Japanese occupation. After the retrocession of Taiwan to the Republic of China in 1945, the capital continued to be Taipei, despite the seriousness of the flooding problem.

At present, one quarter of Taiwan's 18 million people live in the Taipei area. The construction of housing and factories on every available piece of land magnifies the damage done by floods. The low-lying suburb of Mucha, for example, was once a rural area, but now it is densely populated, and floods can wreak havoc.

Unfortunately, flood prevention work can only reduce the extent of the problem, since it is impossible to prevent floods completely. In Taipei, flood prevention work began during the Japanese occupation with the construction in 1915 of a dyke along the Tamshui river near the north of the city. Later, dykes were built along other sections of the river. In 1962 a comprehensive flood prevention plan was drafted but there was not enough money to implement it. The most important projects in the plan involved dykes and drainage systems at Luchou and Sanchung and a drainage canal at Erchung. In 1979 when the plan was submitted for approval, residents objected strongly and construction did not begin until last February.

Creation of the Erchung canal necessitated the relocation of 10,000 residents of Sanchung, many of whom doubted whether it would be useful. One of their main complaints was that compensation was not enough. In the end, some 70 percent agreed to move, and the authorities hope to reach a compromise with the rest before construction proceeds.

But why are dykes necessary? Why not just dredge the rivers? If the rivers were dredged near Taipei their beds would be below sea-level, and would soon be silted up again by sand from the estuary. Dykes are there fore needed because of the topography of the Taipei Basin, and are designed according to the pattern of floods recorded over the past 200 years.

At the moment, Taipei's pumping stations can handle rain falling up to a rate of 45 mm per hour, about the level recorded during an average typhoon.

The drainage system in Taipei is efficient, but sometimes its full potential cannot be realized. A civil engineering professor recently took a group of students to inspect the drainage canals, some of which are as wide as four cars, only to discover that they are often clogged up with such refuse as furniture, dead animals and the like. The authorities are continuously clearing the canals but often the 100 workers employed cannot keep up. Taipei has more than 900 canals with a total length of over 400 km. A NT$5 million machine was purchased to do the work, but was not suitable for local conditions.

Apart from rubbish, sand from construction sites also clogs the canals. More and more houses are being built on hillsides as level land becomes scarcer, and much of the earth dug up for foundations ends up in the drainage canals and rivers. This is largely the result of inexperience on the part of construction companies, and a lack of regulations. A new law covering the problem is expected to be promulgated soon.

Soil conservation is another issue influencing floods. Without trees and plants on hillsides, erosion occurs whenever it rains. The government's planning to invest NT$7 billion on forestation and forest management.

As people become more aware of the problem of flooding, government agencies are cooperating to create a comprehensive strategy to deal with the problem.

While the government presses ahead with construction to prevent flooding, it is trying to teach people the significance of the work so they will cooperate.

As the typhoon season approaches, public awareness as well as government measures are necessary to prevent hardship. Then after a typhoon has passed, there is a danger of continuing rain, and everyone should remain on guard. Most important, the practice of dumping refuse in drainage canals should stop. It is impossible to be 100 percent safe from floods, but a little preventive work by each citizen will go a long way towards reducing the extent of the damage.

[Picture Caption]

1. Taiwan's geography is closely connected with the flooding problem. 2. Wang Wen, a Taipei City Government official, says flood prevention works have reached recognized world standards. 3. Plan for flood prevention in Taipei.

1. Hsu Shih-hsiung says many experts have discussed the Erchung canal. 2. Model of flood prevention construction works, including the controversial Erchung canal. 3. Dykes along river banks play a most important role in flood prevention in Taipei. 4. Professor of civil engineering, Yen Ching-lien, believes that Taipei residents are largely responsible for blocking up the city's storm water drainage canals.

1. Disaster is inevitable if soil conservation is not taken into consideration when building on hillsides. 2. Hsia Wen-hsiung says the government is already taking steps to improve the laws regarding soil and water conservation. 3. Water and soil conservation is a long term process, according to Li San-wei. 4. Forestation is an important part of water and soil conservation.

Wang Wen, a Taipei City Government official, says flood prevention works have reached recognized world standards.

Plan for flood prevention in Taipei.

Hsu Shih-hsiung says many experts have discussed the Erchung canal.

Model of flood prevention construction works, including the controversial Erchung canal.

Dykes along river banks play a most important role in flood prevention in Taipei.

Professor of civil engineering, Yen Ching-lien, believes that Taipei residents are largely responsible for blocking up the city's storm water drainage canals.

Disaster is inevitable if soil conservation is not taken into consideration when building on hillsides.

Hsia Wen-hsiung says the government is already taking steps to improve the laws regarding soil and water conservation.

Water and soil conservation is a long term process, according to Li San-wei.

Forestation is an important part of water and soil conservation.