Sat, Sep 10, 2005 - Page 8 News List

The myth of multipurpose reservoirs

By Chen Hsin-hsiung 陳信雄

The ravages of typhoons Haitang, Matsa and Talim and adjustment releases from the Shihmen Reservoir have muddied the drinking water there, which has led to water shortages in the Taoyuan area. Most Taiwanese feel that the construction of multi-purpose reservoirs is needed to resolve water shortages, while geologists and environmental groups in Europe and the US believe that such reservoirs amount to the rape of nature.

One example is Egypt's Aswan Dam. After its completion in 1960, the soil along the lower reaches of the Nile River suffered severe salinization, parasitic insects invaded the coastal areas, the river delta shrank rapidly and Egypt's total farmland was cut by 15 percent.

This all meant that more than half of all food supplies had to be imported, and the fishing industry at the mouth of the Nile was dealt a fatal blow.

Taiwan has been struck by both droughts and floods in the past few years. The last 50 years of hillside over-development and construction of large multi-purpose reservoirs have led to this shortage of water resources.

An article in the May 20 issue of Japan's Asahi Shimbun said that the US had declared that "the era of reservoir construction has passed."

Since the 1929 depression, the US' New Deal policy, which was aimed at creating jobs and boosting the economy, led to the construction of big multi-purpose reservoirs. From 1902 to 1930, 50 reservoirs were built, but from 1930 to 1980 more than 1,000 reservoirs were constructed.

In May 1994, however, the commissioner of the US' Bureau of Reclamation said that "the era of reservoir construction has passed." His reasons for saying so were that first, given the funds required to build reservoirs, the benefits in the form of water and electricity for agricultural use was limited.

Second, an exaggerated bias toward water for agricultural use could not solve urban water requirements.

Third, there were concerns over soil salinization, a declining fishing industry, disappearing wetlands, destruction of indigenous cultures, agricultural pollution, silt in water-accumulation facilities and dam security.

Fourth, there was environmental destruction, including the ecological systems in rivers and cultural and historical sites. The Bureau of Reclamation therefore proposed that the construction of all planned reservoirs be stopped and that existing reservoirs be destroyed. By May 2001, more than 500 dams or embankments had been torn down.

Taiwan is small and has a large population, but we still build huge reservoirs holding 400 million tonnes of water. Despite this, when comparing the proportion of water-resource distribution via reservoirs, we see that the figure is 23 percent for the US, 10 percent for Japan and 4.7 percent for Taiwan.

For flood prevention, the figure is 17 percent for the US and 3.3 percent for Japan, while in Taiwan, reservoirs are only responsible for 2.3 percent. This is sufficient to show that whether it be for the purposes of flood prevention or water supplies, there are certain limits to the use of reservoirs.

What's more, the geological environment in Taiwan is sensitive, and it is difficult to find locations for large reservoirs. There is also the risk that a reservoir could collapse.

Promoting the reforestation of reservoir-catchment areas and ending over-development and wanton deforestation is the fundamental way to prevent flooding and protect water resources. I hope that the government and the public understand that this is the only way to fulfill our responsibilities to future generations.

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