Sustainable Water Resource Policy in Taiwan
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Sustainable Water Resource Policy in Taiwan Chau-Ling Tyan Chiefofwater resource management division, WRA,MOEA tel:04-22501158 Fax: 04-22501608 E-mail:[email protected] ABSTRACT Water Resources available for each person in Taiwan is only 1/7 of the world average due to uneven precipitation distribution in time and space as well as high population density. In the past, agricultural use was the major water consumption of water resources. Agricultural production might be adjusted according to the amount of precipitation received, irrigated area might be increased during wet period, and decreased or even cease planting when there is water shortage, living conditions and -the social economic development would not be severely affected unless there is severe drought. In recent years, because of urbanization and change in industries, Taiwan is gradually changed from developing century into industrized country, therefore water consumption is also changed from agricultural use to domestic and industrial use. These changes have increased water consumption and the requirements of water quality as well as water supply stability. In addition, these changes have also decreased tolerance to water shortage and affected living conditions as well caused lost is industries. Therefore, the competition among various users for water have become very intense. Water is a limited resource, development beyond the normal limit would damage the environment and rights of our next generation. Under the unfavorable hydrological conditions in Taiwan, water resource related agencies have devoted a tremendous effort to achieve the goal of sustainable use of water resources to meet various reasonable water consumptions with sufficient quantity and good quality. Key words: sustainable water resource l.WATER RESOURCE CHARACTERISTICS IN TAIWAN 9m3 The average annual precipitation reaches 2,SI Smm in Taiwan, which yields 90.Sx 10 ofwater, however, water resources available for each person is only 1/7 of the would average, 1/8 of the United States and 1/4 of Japan due to high population density. In addition, precipitation is unevenly distributed in time and space, the average ratio of wet to dry season in northern, central and southern regions are 6:4, 8:2 and 9:1 respectively, it indicates that the precipitation ratio of wet to dry season is more pronounced toward south of the island. Besides, there is also large difference is annual precipitation, in wet years, annual precipitation reaches 3,2S0mm which is approximately two times of those in dry years (1,600 mrn). This situation is worse in southern region where annual precipitation of the most wet year is seven times of the most dry year. All above-mentioned factors indicate unfavorable hydrological conditions in Taiwan. There are 3/4 of Taiwan is mountainous area causing steep slope and rapid flow in rivers. The annual usable water is relatively low in quantity because 3/4 of runoff flows directly into ocean. The annual usable water is only 1/6 of that in North America and 1/19 of that in South America, which indicates the lack of water resources in Taiwan. Traditionally, reservoirs and weirs are built to store and regulate water, however, storage efficiency in relatively low due to steep terrain and narrow valleys. For example, the Three 481 Gorge dam in China is 185m high with storage volume of39.3xl09m3 which is approximately 2.: 170 times of Deji Reservoir in Taiwan with dam height of 180m and storage volume of Ai 0.23 x109m3. Water resources development and utilization are difficult in Taiwan. ch co nc 2. PRESENT WATER RESOURCES UTILIZATION IN TAIWAN 101 fu 2.1 Present Water Utilization S< th According to the "Summary Report of Various Water Consumptions in Taiwan, year 2001", the 9m3 total water consumption was 18.48x 10 in year 2001. As shown in Figure 1, a~ricultural water used the largest quantity of 13.01 x109m3 (70.4%), domestic water used 3.73 x10 m3 (20.2%) and industrial water used 1.74x 109m3 (9.4%), they are described as follows: 2.1.1 Agricultural Water Use 9m3 As indicated in Table 1, the total agricultural water consumption is 13.01 x10 , in which 3. irrigation uses 11.48x109m3 (88.2%), pisiculture uses 1.42xl09m3 (10.9%) and live stock uses 9m3 A 0.11 x10 (0.9%). When agricultural water use is summarized by regions, Central Region uses 9m3 9m3 T the largest quantity of 5.72 xl0 , the Northern, Southern and Eastern Regions are 2.29 x10 , 9m3 2.57x 10 and 2.43 xl 09m3 respectively. 3 2.1.2 Domestic Water Use 9m3 As indicated in Table 2, the total domestic water consumption is 3.73 x10 , in which J. 3.47xI09m3 (93.0%) of water is supplied by Water Company and 0.26x109m3 (7.0%) is self f supplied. When domestic water use is summarized by regions, Northern Region uses the largest , 9m3 9m3 quantity of 1.97xl09m3, Central, Southern and Eastern Regions are 0.81 x10 , 0.85 xI0 and s 0.1Ox 109m3 respectively. 2.1.3 Industrial Water Use 9m3 As indicated in Table 3, the total industrial water consumption is 1.74 X10 , in which 0.53x109m3 (30.5%) is supplied by Water Company and 1.21xI09m3 (69.5%) is self supplied. When industrial water use is summarized by regions, Northern Region uses the largest quantity of 9 0.63xl09 m 3 , Central, Southern and Eastern Regions. are 0.5xlO 9m3 ,0.55 xlO 9m 3 an d 0. 0 6x 10 m 3 respectively. 2.2 Trend of Water Resources Utilization Various water consumption from year 1983 to 2001 are summarized in Table 4 and Figure 2. The trend of water resources utilization indicates that agricultural water consumption has been decreased, however, it increases after year 1999; domestic water consumption have increased 3 9m3 127% from 1.64xl09m in year 1983 to 3.73 x10 in year 2001; and industrial water 9m3 consumptions have increased 15% from 1.51 xl 09m3 in year 1983 to 1.74x 10 in year 2001. 482 oximately 2.3 Estimate of Future Water Demands olume of After joining WTO, agricultural policies should be adjusted accordingly. The import of rice, change planting of rice fields and release of farmland would reduce irrigational water consumption to some extent, however, the reduced amount of irrigational water consumption is not clear at the present time because of the agricultural policy has not yet been settled. As indicated in Table 5, the promotion of tourism industries by the government would increase the future domestic water consumption to 4.22x109m3 in year 2021. According to the National Science Committee and Industrial Bureau of MOEA, the future industrial water demands under 9m3 9m3 the assumptions of low, medium and high growth in year 2021 will be 1.24 x10 , 1.71 x10 )01", the 9m3 ral water and 2.01x10 respectively. Under the condition that agricultural water consumption remains the same as current (12.0 x109m\ by adding 1.5x109m3 of conservation water, the total water .2%)and 9m3 9m3 9m3 demands in year 2021 could add up to 20.7 x10 , 21.2x10 and 21.5x10 respectively depending on the growth of industrial water consumptions. n which 3. CURRENT PROBLEMS OF WATER RESOURCES UTILIZATION )ck uses Ion uses After reviewing the water resources characteristics, current utilization and future trends m 9 3 x10 m , Taiwan, problems need to be resolved including the following issues: 3.1 Decrease of Water Shortage Tolerant Extent and Increase of Water Quality and quantify Requirements Cause by Raising Living Standards and Changing of Industries which Agriculture was the main industry in the past in Taiwan. Water for agricultural use has a large , is self flexibility, it can be reduced when necessary for supporting domestic water supply, therefore . largest , 3 water shortage would not significantly affect economy and people's livelihood unless there is a m and severe drought. Recently, economy is developing toward electronic industries, the needs for stable water supply have been increased because the industries can not stand any water shortage, and water shortage would cause severe loss to the economy (for example, 2% water shortage would cause suspension of 50% of production work). The high water quality standards required for domestic and high technology industries would also cause lost of water during treatment which processes, and therefore increase water demands indirectly. pplied. rtity of [109m3 3.2 Lack ofWater Supply Stability The water consumption in Taiwan from year 1998 to 2001 (Figure 3) indicated that average 9m3 annual total water consumption is approximately 18.0x 10 , in which agricultural water 9m3 9m3 consumption is 12.4x10 , domestic and industrial water consumptions are 5.1 x10 , and 9m3 conservation water is 0.5xI0 . Under the condition of 90% water supply stability, domestic ure 2. and industrial water consumption need 5.1 x109m3 of reliable water sources. Reservoirs in ~ been Taiwan have a total storage volume of2.0x109m3 which can provide approximately 4.6 xI09m3 of reased water annually, after subtracting 1.5x 109m3 for agricultural use, there is only 3.1 x109m3 of water [water left for domestic and industrial consumptions with about 60% stability. To make up the demand 9m3 9m3 ~l. of 5.1x10 , the remaining 2.0x10 has to be taken from surface runoff and groundwater. However, groundwater has been over drawn in some areas recently, surface runoff with 95% stability has to be reserved for conservation water. In addition, water quality in mid and 483 downstream of rivers are polluted, and the recent meteorological conditions have been changed. The above-motioned reasons have made water storage for present conditions, and water shortage will become worse as the water demands increase in the future.