It Never Rains But It Pours--Solving the Water Problem

On August 24 Typhoon Aere brought torrential rainfall that reached an average 1,300 millimeters within two days in the northern part of the country. The Shihmen Reservoir watershed in Taoyuan recorded an average rainfall of over 1,000 millimeters, setting a 40-year record.

Because the mountainous soil was unable to absorb this staggering amount of rainfall, landslides resulted. A great deal of silt was thus mixed in the water, and the water in the Shihmen Reservoir reached a turbidity level of over 10,000 NTU (nephelometric turbidity units), whereas water treatment plants cannot produce potable water if turbidity rises far above 1000 NTU. As a consequence, the five water treatment plants in the Taoyuan area at Pingchen, Ta-nan, Lungtan and Shihmen shut down. Two million inhabitants of Taoyuan and Taipei Counties were plunged into a nightmare of torrential rains followed by a complete loss of mains water supply.

Just give us some water!

During previous typhoons, after a flood release from the reservoir, it was always possible to wait a few days for the river water to clear up and start providing potable water again. But this time people were not so lucky. Six or seven days after Aere the turbidity of the water remained high, leading to Taoyuan being declared a disaster area due to a severe water shortage, and a war of words broke out between local and central authorities over responsibility.

Taoyuan County commissioner Chu Li-lun, aside from issuing a high-decibel demand that the central government quickly solve the Taoyuan water shortage, took measures to increase supply and ration usage. Top priority was given to water for home use. The county's more than 1,600 registered underground wells were opened for public use and the ban on drilling deep wells was temporarily lifted.

In addition, the Ministry of Economic Affairs shunted water from the Panhsin water treatment plant to help the Taoyuan area, and instituted an emergency project to set up temporary pumping stations on the reservoir after-bay, to pull off the relatively clean surface water and move it forward to the Shihmen main channel, and from there to the Pingchen treatment plant, completing within a few days a project that would ordinarily have taken months.

After six days and nights of frenetic activity, the temporary pumping facilities at the Shihmen after-bay came on line early in the morning of September 5. The residents of southern Taoyuan County, who had experienced a 12-day water stoppage, were finally able to begin receiving water alternately area by area.

On September 9 the second temporary pumping station project, this one at the Tapa-Sungtai section of the Shihmen Reservoir, was finished. Raw water was pumped to three 70-ton water tanks, from there via pipes to the Shihmen main channel to provide 200,000 to 250,000 tons of water to Pingchen, Lungtan, Yangmei, Chungli and Hsinwu, finally ending the nightmare of the 16-day water shortage.

But these were only stopgap measures. They do not represent an ultimate solution to Taiwan's increasingly serious water resource problems; moreover, the urgent pressure to provide water may lead to a reduction in the reservoir's useful life. During this period a Taiwan Water Corporation worker died of overwork, having been sent out night and day to do his job. His death saddened and shocked everyone.

Feitsui vs. Shihmen

Some people wonder why, with the same torrential rains, the Feitsui Reservoir can provide water while Shihmen cannot.

The director of the Taipei Water Department, Kuo Jui-hua, points out that while the water storage capacity of Shihmen Reservoir is only one half that of Feitsui, its surface area is twice that of Feitsui. Also, upstream soil conservation work is difficult, which exacerbates the consequences of any disaster like that caused by Aere.

The original function of the Shihmen Reservoir, completed in 1963, was principally irrigation. Aside from the outflow channels meant for agricultural irrigation, no others meant exclusively for supplying water to the public were built. But today, 40 years later, the population in the Taoyuan region has increased dramatically and many factories have grown up in the industrial areas. The function of the reservoir has long since changed from irrigation to providing public water, but the channels have remained the same. In the past, water was taken from the reservoir via low-level channels. The water had a high turbidity level, but the silt it carried in fact helped increase the fertility of farmland. But if the water fed into a water treatment plant is too turbid, the plant will be choked and stop working.

In the wake of Typhoon Aere there is an estimated 20 million tons of additional silt in the reservoir, eating up about 10% of the reservoir's total capacity. The normal method for maintaining the life of a reservoir is to use flood releases to carry out the silt. But because this increases turbidity, in an effort to get water to people and factories as soon as possible policymakers issued an order not to use this method, and instead to carry through a project to utilize reservoir surface water. This way, although water service can be restored more quickly, the degree of silting in the reservoir is likely to be increased and its life reduced.

The Shihmen reservoir could originally hold 280 million tons of water. After 40 years of silt buildup, its capacity has dropped to 250 million tons. Hydrologists worry that if we now use the clean surface water of the reservoir and leave the 20 million tons of silt added by Aere at the base, then once the mud settles it will harden and be impossible to remove. According to the estimates of Chung Chao-kung, deputy director of the Northern Region Water Resources Office, if the silt added by Aere is not removed, the reservoir's capacity will be decreased by 10% and its life shortened by seven years.

The all-out effort to provide water also entailed other losses. The Shihmen electric power plant was ordered to suspend operations, which allowed silt to settle in the turbines, in all likelihood making this NT$200 million investment a write-off.

"Take water from different levels" is a fundamental rule of thumb of reservoir operation. In fact, after Typhoon Nari in 2001 there was a water stoppage at Shihmen Reservoir because the raw water could not be taken due to its excessive turbidity. At the time Lin Hsin-i, minister of economic affairs, began discussions on setting up a second water outlet for Shihmen Reservoir at Pingchen. If things had gone according to plan, this project would have been finished last year, but for a variety of reasons, including project design, environmental impact statement, land expropriation, and resistance from local elected representatives, the project was delayed and remains unfinished.

Excessive land use to blame?

On September 9 Premier Yu Shyi-kun led a group on a helicopter inspection tour of the watershed area upstream of Shihmen Reservoir. The group comprised Minister of Economic Affairs Ho Mei-yueh, Minister-without-portfolio Lin Sheng-feng, Cabinet Spokesman Chen Chi-mai, Professor Huang Hung-pin from the Department of Bio-environmental Systems Engineering and Professor Jeng Fu-shu from the Civil Engineering Department, both at National Taiwan University. Their conclusion: the three main culprits behind the Shihmen problem were the failure to take measures to prevent soil erosion during slopeland forestation, the expansion of farming activities, and road construction in mountain areas.

Lin Sheng-feng pointed out that aside from the excessive amount of rainfall one cause was excessive land use in Taoyuan County's Fuhsing Rural Township and Hsinchu County's Chienshih Rural Township, both located within the watershed of Shihmen Reservoir, where the land area used for orchards has increased by 1,020 hectares compared with 1998. Overall, some 938.3 hectares have been developed over the permissible limit, he said.

Premier Yu directed the Council for Economic Planning and Development to draft a bill on land remediation and conservation, conduct an overall review of policy on farming in mountain areas and also offer the public reasonable compensation.

This typhoon caused the people of Taoyuan a great deal of pain and suffering as they were forced to go without water for many days. Industrial losses are estimated at NT$10 billion. Heads of agencies at the local and central government level are exhausted by their efforts. The chairman and the CEO of Taiwan Water Corporation stepped down, and there was a strong reaction among the corporation's employees. The ironic thing is that while excess water was repeatedly discharged from the reservoir, the public still got no water. This highlighted the problems with Taiwan's water resources and water allocation policies.

Because of Taiwan's topography, its rivers are short and fast moving, and it is difficult to store large bodies of water. From north to south each of the 30 reservoirs that provides tapwater is an independent entity. If they all could be linked together and a water distribution network created, then water from the south could be moved to the north and water from the north could be used to aid the central region, thus avoiding the awkward situation of some localities having a surplus of water while others have a shortage.

Minister of Economic Affairs Ho Mei-yueh will shortly summon relevant officials to discuss the current system for supplying tap water in the hope of quickly adding new systems or creating more pipelines to link reservoirs, water treatment plants and water supply systems in an inter-regional water distribution network. In the mid- and long-term, the plan is to ameliorate the serious water problem in some areas through new facilities like reservoirs in flatland areas and seawater desalination plants.

Natural vs. man-made disasters

No sooner had the water shortage in Taoyuan been overcome when the floods of September 11 arrived.

Northern Taiwan was deluged September 11 by torrential rains brought in by southwesterly airflows. The huge and sudden downpour could not be immediately absorbed and created flooding for more than 4,000 residents in Hsichih, Sanchung, and Hsinchuang in Taipei County as well as in the Nankang and Tunghu Districts and Yungchi Road in Taipei City. People in some parts of Taoyuan County who had already suffered a water shortage now also went through a baptism of flooding.

In recent years worldwide weather patterns have been unusual. In September of this year alone, including the US, Japan and mainland China, there has been a stream of violent storms and floods. In Taiwan, Typhoon Xangsane in 2000 brought rainfall that exceeded levels expected only once a century, then in 2001 Toraji and Nari exceeded 200-year levels, and now this year Aere and the September 11 floods have posted new rainfall records. But what lessons has the government taken from the torment of water shortages and flooding people have endured and the threat to their lives, livelihood and property?

Minister Ho Mei-yueh, who offered to resign several times because of the Taoyuan incident, says that this water shortage was indeed a natural disaster, but in its response to the disaster the Ministry of Economic Affairs is not without some responsibility. If it had put in place some control mechanism to deal with water resources when there was time, damage would have been somewhat less. "It wasn't until we turned on the tap and discovered there was no water that we understood the depth of the problem. We must learn from what went wrong," she says with deep feeling.

After the September 11 floods the Taipei City government held a forum at which it frankly admitted that the main reason for the flooding in Sanchung and Tunghu was that rainfall was much more than predicted, the flood warnings were issued too late, and the Taipei mass rapid transit construction work in the Sanchung area was not up to standard. The city government was in no position to absolve itself of blame and it intended to give victims monetary relief in line with the central government's natural disaster emergency relief guidelines. It would also build another pumping station to increase pumping capacity, to avoid the recurrence of a similar disaster in the future.

Natural disasters are hard to predict but man-made disasters can be avoided. One can only hope that the central government and local governments will work hand