Rivers, streams, ponds, groundwater- above and below the ground of Taiwan, there are many natural sources of water. So why does the water we drink come from reservoirs?
Ever since the Feitsui Reservoir was built, ask anyone from Taipei: "Where does the water you drink come from?" Almost without needing to think, they all answer: "The Fei-tsui Reservoir!"
In fact, the waterworks which treat Taipei City's public water supply usually take their water from the natural flow of the Nanshih and Peishih rivers. It is only in the dry season, when these rivers do not provide enough water, that the supply has to be topped up with water from the Feitsui Reservoir. Because northern Taiwan has abundant rainfall, it was not until 12 years after the reservoir was filled, during the series of islandwide droughts from 1991 onwards, that Greater Taipei made real use of water from the Feitsui Reservoir.
Cities are the body, rivers the arteries
Modern hydrologists divide the water resources available to humans into the categories of surface water (rivers, lakes etc.), groundwater, and reservoirs.
Rivers and lakes are in fact the most convenient sources of water. In ancient times, many great cities were built beside rivers, mainly because the river ensured an abundant water supply for the residents. Particularly if the upper reaches of a river were heavily wooded, the forests would act as a buffer for rainwater, making the river's flow gentle and regular. For the human and animal consumers of water, forests and rivers are natural reservoirs.
Apart from rivers, and channels cut to divert water through cities, many cities were dotted with lakes and ponds large and small. These not only gave people somewhere to relax away from the noise of the city, but also provided sources of water. In the Southern Song dynasty (1127-1279), Hangzhou's West Lake was not only a natural reservoir, but also a beautiful scenic spot where, in the words of the poet, warm breezes blew to intoxicate a traveler's spirit.
Groundwater can also be obtained with little effort. When rain falls from the heavens groundwater is naturally replenished, and for thousands of years Chinese farmers have sung: "We work from sunrise/ We rest at sunset/ We dig wells for water/ What do we care about the might of emperors?" The ceaseless supply of groundwater bubbling up from wells enabled people to drink when they were thirsty and wash when they were dusty, and allowed agricultural society to ignore the power of emperors and self-confidently affirm that people's value came from living on the land.
As for artificial reservoirs, building dams across rivers to hold back water is not a modern invention, but the widespread construction of large dams is a 20th-century phenomenon. In these days of urban sprawl and burgeoning industry, humans' demand for water has increased vastly, and with improvements in materials and technology, reservoirs have become the mainstay of water resource planning.
In August this year, Typhoon Herb brought Mt. Ali almost a year's average rainfall. For Taiwan, with its erratic precipitation, reservoirs really can smooth out the supply of water. Tsou Chen-ming, principal of Tao-yuan's Chunghsing Elementary School, says that in his boyhood, before the Shihmen Reservoir existed, in the dry season Taoyuan people often had to pray for rain. But the reservoir released them from the scourge of water shortages in the dry summer.
An engineer's nightmare
Although reservoirs mean people no longer have to tailor their water consumption to the weather, unlike the ever-flowing natural reservoirs, artificial reservoirs are "born to die." "What's more," says NTU geography professor Chang Shih-chiao, "from an engineering standpoint, Taiwan doesn't have any suitable sites to build dams."
The island of Taiwan is small with an unstable geology, and its rivers are short and fast-flowing. These factors together give rise to astounding rates of silt flow. Taiwan's western plains were built from sediment washed down by the rivers, and 300 years ago when Zheng Chenggong (Koxinga) opened up Taiwan for settlement from the mainland, the many thousands of hectares of land in Tainan's fourth and fifth development zones were still under the ocean.
Taiwan's rivers are an engineer's nightmare. Often a single torrential tropical rainstorm will fill silt traps and weirs full of silt. Removing silt is too costly and is impractical, and so once these structures are overwhelmed, they simply become part of the river bed. Water engineer Hong-Yuan Lee says that from weirs to silt traps to reservoirs, "their useful life in Taiwan is not even one-fifth of what it would be for the same structures in continental countries."
In continental countries with their broad terrain, long meandering rivers and gentle slopes, the useful life of a reservoir may be more than a century, and their water storage capacity also far exceeds that of dams built across Taiwan's steep, narrow valleys.
Mainland China's Three Gorges Dam will be 180 meters high, the same height as Taiwan's Techi Dam. But its storage capacity will be more than 21 billion tonnes, 70 times greater than Techi Reservoir's 300 million tonnes. The Shihmen Reservoir is 16 kilometers long. This may seem a lot, but many dams of the same height in Canada or the USA hold back lakes one or two hundred kilometers long, with capacities greater than all Taiwan's 30-odd reservoirs put together.
A dam is an enormous engineering structure, and an investment which has to be paid in all at once-it cannot be built in easy installments. To construct a reservoir today takes an investment of over NT$10 billion, and Taiwan is not a good place to build reservoirs, so the return on the investment falls far short of that achieved in continental countries. Thus we should not be using reservoirs as "normal" water resources. Costly reservoirs should be seen as a last resort. In Taiwan, with its irregular rainfall, says Chang Shih-chiao, "reservoirs are very important," but they are an emergency backup.
Are you drinking recycled sewage?
Since we cannot rely on reservoirs forever, we should find ways to postpone their construction in order to leave later generations with sites in reserve; but for a long time little value has been placed on "normal" water resources such as rivers and groundwater.
Today, Taiwan's groundwater is polluted with agricultural pesticide and fertilizer residues and with heavy metals, and excessive pumping by illegal fish farms means that Taiwan's annual abstraction rate exceeds the natural rate of replenishment. This has led to land subsidence along both the eastern and western coasts.
On a map of river water quality produced by the EPA, 50 of Taiwan's major and minor rivers are colored black or brown from their mouths to their middle and upper reaches, indicating that they are heavily or moderately polluted.
The Panchiao-Hsinchuang waterworks, downstream from the Shihmen Reservoir, supplies water to over a million people in Panchiao, Hsinchuang and Shulin. But along the 16 kilometers of the Tahan River from the Shihmen Reservoir to the waterworks, there are the Shihmen, Tahsi and Yingko urban development areas, which have over 70,000 inhabitants, but no sewage treatment systems. All along the river bed are gravel pits, refuse dumps and heaps of discarded electric cables, and there has been an incident of radioactive waste seeping into the river from the nearby Chungshan Institute of Science and Technology. This is why one office worker who moved with her family to Shulin in Taipei County sees no choice but to buy mineral water by the tankful. Although research reports say that the Shihmen Reservoir's water quality is poor, the Tahan River, which in the dry season fails half of nearly 20 different water quality tests, relies on water released from the reservoir to "dilute" its pollution.
To date less than 4% of homes in Taiwan Province are connected to a sewage system, and domestic sewage is largely discharged directly into rivers. The dikes built along Taiwan's rivers not only hold back floods, but also the stench of their waters.
As the cheap, clean supply of water from rivers has been polluted and exhausted, riverside culture has also declined. Sanhsia in Taipei County is an ancient little town, and its small-town atmosphere came mainly from its Tzushih Temple, with its back to Mt. Yuan and the Sanhsia River flowing past in front of it. But today, with Taipei County's ever-worsening water shortage, a weir is planned for the upper part of the Sanhsia River, which is only 10 kilometers long in total. The river bed in front of Tzushih Temple may dry up, and some people worry that without the river as its companion, the Tzushih Temple, which has survived so many years, will no longer be the old Tzushih Temple, and Sanhsia will no longer be the old Sanhsia.
The many ponds which used to be dotted about the Taoyuan plateau were laboriously dug, spadeful by spadeful, by settlers who cleared the land a century ago. Apart from their functions of flood control and regulating the temperature, they were also intended to store water to get people through times of drought. When Taoyuan's ponds were gradually turned into building sites and covered over with concrete, the need for Shihmen Reservoir was created.
Seeing Taiwan's ever-growing reliance on reservoirs, Professor Hong-Yuan Lee of NTU's civil engineering department says: "We have forced ourselves along this road."
Build them to the top of Mt. Yu!
Thus a succession of reservoirs intended to perform power generation, water storage and irrigation functions have been built along Taiwan's rivers large and small. "Taiwan's second largest river, the Tachia River, has four reservoirs. From top to bottom these are the Techi, Chingshan, Kukuan and Tianlun reservoirs." Isn't that what every senior high school student has learned by heart and been tested on?
Although rivers and groundwater are still Taiwan's most important water resources, Huang Chin-shan, vice director of the Taiwan Province Water Conservancy Bureau, calculates on the basis of Taiwan's natural environment, engineering capability and other factors that for reservoirs to provide more than 25% of Taiwan's water supply is not economic, and to continue building reservoirs beyond that point is a loss-making undertaking. But today Taiwan draws almost 20% of its public water supply from reservoirs, and for drinking water this figure rises to over 50%. Yet the Water Resources Planning Commission, Council for Economic Planning and Development and other agencies responsible for water resource planning are constantly planning and promoting the construction of reservoirs, from the Machia and Meinung reservoirs in southern Taiwan to the Pinglin Reservoir in Taipei County. According to the Ministry of Economic Affairs' latest information, there are currently six reservoirs under construction in Taiwan and another 16 being planned.
Under pressure from human damage, one reservoir after another has filled up with silt and lost its ability to supply water. Dependent on the Shihmen Reservoir, people in Taoyuan City and County are again holding frequent ceremonies to pray for rain. In the face of renewed water shortages, one can only build reservoirs further and further up the rivers. But as water sources recede up the rivers, pipelines become ever longer and losses from leakage ever more severe, and people's relationship with water becomes more and more remote, so that they care less and less about their water resources.
"You can build them up to the top of Mt. Yu if you want!" Wu Chien-min, chairman of the Ministry of Economic Affairs' Water Resources Planning Commission, says that everyone thinks that if there is a lack of water, all that needs to be done is to build more reservoirs. But unfortunately rain doesn't fall in torrents straight into reservoirs-the higher reservoirs are built, the smaller their water catchment areas become, and the less water they are able to trap. Treating reservoirs as the only option also leads to them being used inefficiently. Chang Shih-chiao observes that it is only in the last few years that the Feitsui Reservoir has really come into use; before that, in fact the investment was wasted.
According to statistics compiled by NTU's civil engineering department, the water resources available annually to each person in Taiwan are only one-seventh of the world average. In other words, water in Taiwan is scarce. But the average water charges of NT$7 to NT$9 per unit levied in the Taiwan Area are among the cheapest of any developing or developed nation. One of the reasons is that at present the water companies use water from reservoirs, but the cost of constructing the reservoirs is borne separately by the government. If all the costs of investment in fixed assets such as reservoirs, pipes and purification plants were properly calculated and reflected in water charges, water in Taiwan would actually be more expensive than petrol: "It would cost at least three times what it does now, or about NT$20 per unit," says Yang Chung-hsin, a research fellow at the Academia Sinica's Institute of Economics.
The Yangtze no longer rolls unfettered
Every generation needs water resources, and we should not merely plan to rely on engineering solutions. All the more so since no matter how long the useful life of a reservoir, the negative side effects of dams cannot be solved by current engineering methods, and the more reservoirs we build, the greater the damage done to cultures and communities. The mainland's Three Gorges Reservoir has not yet begun to fill with water, but it has already forced several hundred thousand people from their homes. A mighty dam spanning a great river cuts the flow of its waters into two, and the sight of the Yangtze's rolling waters flowing eastward as described by poets will no longer exist. This destruction of a cultural heritage is one of the reasons behind opposition to the Three Gorges project.
Greater Taipei's Feitsui and Shihmen Reservoirs too have both drowned many people's homes and many people's memories, and have also damaged the environment. The Kanehira azalea and the tree frog Rhaco-phorus prasinatus, which were only found at Hsintien and Pinglin, have both been decimated by the Feitsui Reservoir. The people of Pishan and two other villages in Shihting Rural Township once had a road by which they could enter and leave their villages, but today the road is under water, and their only access is by boat. "You can't go home too late at night," says a resident of one of Pishan Village's orange groves, because after six o'clock there's no boat. The threat to Hakka culture from the construction of the Meinung Reservoir caused calls to oppose the reservoir to find resonance throughout Taiwan.
The use of water resources should be founded in nature and humanity. Taiwan's aboriginals regarded their water sources as sacred lands. The Paiwan and Rukai tribes forbade hunters to enter the lands of their ancestral spirits in the Tawu Mountains, which were also their source of water, because they were "so sacred that they must be inviolate."
Professor Ouyang Chiao-hui of National Central University once proposed that the government should designate one day each year on which water supplies would be shut off, to remind the nation of the scarcity of water resources, and to encourage people to stop wasting water. When a "Best Water" competition is held in Japan today to choose the locality with the best water quality nationwide, the purpose is to remind everyone to cherish water resources.
It has been suggested by scholars that if the ponds on the Taoyuan plateau had been deepened to increase their storage capacity, and if pollution from livestock and aquacul-ture had been avoided, it might not have been necessary to build the Shihmen reservoir. The ponds large and small would not only have less impact on the scenery and maintain a more human visual scale, but would also be less risky than concentrating all one's water resources in one large manmade lake.
In keeping with their ideal of "keeping many lakes to reflect the bright moon, so that one need not worry that there is nowhere to cast the golden hook," when the Chinese of the Tang dynasty (618-907) planned their cities, they kept many open spaces within them for lakes and ponds, in order to provide a water supply and to absorb flood waters. To avoid pollution of rivers and lakes, Beijing in the Yuan dynasty (1206-1368) had sewers two storeys tall, and even in the Qin dynasty (221-206BC) cities had clay sewage pipes.
Water consumption: a mark of civilization?
Liao Shu-liang, director of National Central University's Graduate Institute of Environmental Engineering, goes further when he says that today's national development policies should take account of the ecosystem as a whole. The standard of living and lifestyle, and the degree of material development and consumption which can be supported, should be decided according to the water resources available. It is on this basis in turn that the type and scale of development and exploitation should be decided.
But Taiwan's water resource planners' status in the policy-making hierarchy has been too low. The Water Resources Planning Commission and the Department of Water Resources are both subordinate to the Ministry of Economic Affairs. Economic development is planned with an attitude of "I want development, you go and find me water," and hence the use of water resources lacks a long-term view. For instance, the Kaohsiung-Ping-tung area of southern Taiwan has a long dry season and very irregular rainfall. With only one large river system, the Kaoping River, it lacks adequate water resources, and to this day Pingtung relies on pumping up ground-water. But despite this the area has been developed into a heavy industrial region with a high water consumption.
Liao Shu-liang describes the situation thus: "The departments promoting the exploitation of economic resources have done their work so well that the departments charged with conserving resources can't keep up." Because the authorities which manage water resources and those which manage their use do not coordinate their work, the consuming authorities actively promote water use and allow water consumption to grow year by year. But when water runs short and problems appear, they lack any alternative plans, and can only choose the policy of last resort-building reservoirs.
"Water is a limiting factor for economic development, so we should make the best use of it within these limits. It should not simply be a case of the economy forging ahead and water resources tagging along behind picking up the pieces," says Liao Shu-liang.
In fact, methods such as reducing the scale of consuming industries and encouraging industry to save water, or constructing waste water recycling systems, are all ways by which national water use could return to normality, and not have to demand even more water from nature. As the national standard of living rises, water consumption need not necessarily rise with it.
Although Taiwan is said to be short of water, when one compares its total annual rainfall of 2500 millimeters with that of many other countries, such as Israel which only gets 600 mm, some others are far worse off. "How can you say Taiwan is short of water?" asks Professor Chen Hsin-hsiung of NTU's forestry department. Although reservoirs themselves are inherently harmful in many ways, the real nub of today's lack of water is everyone's unhealthy attitude towards the resource. Hence, "however many mighty dams you build, they won't hold enough water."
Sky water needs no fence
When Zheng Chenggong accepted the Dutch surrender in Tainan, the Chianan Plain, which straddles the Tropic of Cancer, was still a dry, sandy wilderness. For Zheng's troops the first step towards creating farmland was to find water, so they dug ponds and ditches, and developed a three-year crop rotation system for the Chianan Plain. People took turns to plant paddy rice once every three years, and in the intervening years grew mainly dry-field crops. Gradually this three-year rotation could no longer fill the needs of the growing population, and the amount of farmland was continuously expanded. Then industry came and the towns grew, and finally Taiwan's first large reservoir, the Tsengwen Reservoir, was built in southern Taiwan. Today, a large petrochemical plant and a steelworks are to be constructed in the Pinnan Industrial Zone, and the Nanhua, Meinung and Machia reservoirs are to be built to feed them.
Wu Chien-min, who feels he has little choice but to do water engineering all his life, says that here in Taiwan, we have always followed a supply-oriented water resource policy, so we have been forced to rely on engineering works. "Now it's time we slowed down and controlled our demand," he says.
"Sky water. It needs no fence. Nations come and go without defiling it. It is a mirror which no stone can crack, whose quicksilver will never wear off, whose gilding Nature continually repairs; no storms, no dust, can dim its surface ever fresh;-a mirror in which all impurity presented to it sinks, swept and dusted by the sun's hazy brush. . . ." It is with these words that Henry David Thoreau describes water in the world of nature, in his Walden; or Life in the Woods-as rivers, lakes and ponds. But what words should we use to describe an artificial body of water fenced in by a dam which obstructs a river's rolling flow?
"I want to row a dragon boat too!" Rivers and lakes are not only the best source of water, but are also the cradle of cultures. Every year the two villages of Upper and Lower Erhlung ("Two Dragons") in Ilan County compete against each other in dragon boat races. (photo by Diago Chiu)
When the Feitsui Reservoir was filled with water, it drowned the Kane-hira azalea, a rhododendron species unique to Taiwan. It is only thanks to rehabilitation work by the Taiwan Endemic Species Research Institute in recent years that this elegant plant can once again be seen growing next to streams and in cracks in rocks.
In the past people thought only of the benefits reservoirs would bring. But after seeing them drown many people's homes and memories, people have gradually come to be concerned about the environmental and ecological damage which large manmade lakes can cause. Our picture shows villagers from Shihting Rural Township who, because of the Feitsui Reservoir, can now only reach their homes by boat.
Pumping of groundwater by illegal fish farms has caused a "drought" in this naturally replenished, renewable source of water, and has also led to land subsidence. At Linpien in Pingtung County, many houses have subsided, and as the eaves sink lower and lower, adults have to bow their heads to enter. (photo by Cheng Yuan-ching)
With the rivers in the plains polluted and fetid, people continue to seek water further and further upstream. But as our sources of water move ever further away, people's relationship with water becomes increasingly distant, and they cherish their water resources less and less.
Oppose reservoirs? Save our water resources? Only by first saving our water resources and cleaning up our water catchment areas can we reduce the demand for reservoirs. (photo by Hsueh Chi-kuang)