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Controlling floodwater is all about good policy

Tropical Storm Kalmaegi has once again exposed the fragility of Taiwan’s environment. This, together with the threat posed by global warming, makes it necessary for the government to adjust its flood-control policy. The current strategy, which focuses on drainage and dike construction, should be reinforced with a water conservation strategy that integrates with the natural environment.

In addition to flooding, another problem is insufficient water resources during droughts. Current flood-control policy focuses on drainage and dike construction that rapidly directs large volumes of water from typhoons into rivers and the sea, wasting precious water resources while increasing the strain on local drainage systems and rivers.

More importantly, when abnormally high rainfall hits Taiwan, as with the extremely heavy rains brought by Kalmaegi, flooding is inevitable.

An advanced flood-control policy should consider how to retain water and reduce the strain on drainage systems and rivers. Today there is no suitable location for a large reservoir in the mountain areas. A more feasible strategy would be for the Forestry Bureau and the Soil and Water Conservation Bureau to strengthen soil and water conservation in the mountains to improve the water conservation functions of forests.

At the same time, they can build a number of ponds in the mountains using ecological engineering. They can be used as “ecosystem ponds” or else be used for irrigation. When a typhoon approaches, they can be emptied and used to retain as much rainwater from the storm as possible, thus avoiding or decreasing flooding in the plains.

For residential, commercial and industrial areas, and all schools and government agencies in the plains, a system for recycling rainwater should be promoted so that surface runoff on flat ground and in urban areas can be used to create a green environment. The government can allocate part of its flood-control budget for subsidies and help tens of thousands of communities across the country recycle rainwater. This would relieve the pressure on urban drainage systems.

Low-lying areas in the western plain and coastal areas that suffer most from flooding can be developed into small and medium “flood retention pools” through land planning and rezoning. These pools can catch rainwater brought by typhoons and irrigate crops or supply water to aqua farms.

Meanwhile, dirt dug out from the pool sites could be used to elevate neighboring areas and build new communities. Since these communities would be free from flooding, the price of land there would be higher than in flood-prone areas. The government could thus trade the new land for the pool sites without having to levy land taxes.

Such flood-control strategies would decentralize water conservation. With a lot of small and medium-sized projects in the mountains, urban areas, the plains and coastal areas, we can promote water conservation through accumulation. This could also remedy the weakness of the present flood-control policy, which focuses too heavily on drainage and dikes.

The current flood-control policy is costly, has limited effect and does not promote the retention of rainfall. Implementing the strategies proposed here would have the same effect as building more large dams but without damaging the environment.

If the government, academia and civil groups can reach a consensus and push for new strategies, we would have a chance to resolve the nation’s water problems, allowing it to move toward sustainable development.



Sun Chih-hong is a professor in the Department of Geography at National Taiwan University.

Translated by Eddy Chang
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