Meteorologically and geographically speaking, Taiwan island lies in the semi-tropical zone, where typhoons and thunder-storms have occasionally brought floods and damages, at least once every year. The rainfall is very abundant but with rather uneven distribution. In rainy region, the maximum yearly precipitation ranges around 8,800 mm, while on the other hand, in places of meager rainfall, the minimum is sometimes as low as 413 mm. The rainy days may be as many as twenty in a month. Such high intensity and uneven distribution of the rainfall have made the river flows sudden and torrential for each storm, but during the winter season, the rivers run almost dry. All these peculiarities show that hydraulic construction in Taiwan should play a very important role. Had it not been developed, the agricultural production would have naturally decreased to a minimum and any enterprise of material reconstruction would have consequently been paralyzed. Judging from this point, hydraulic work development is actually the foundation of the economy in Taiwan, and the control of water for beneficial use must, therefore, be our first concern in any scheme of reconstruction planning.
I. River and Irrigation Works Before the Take-Over
The rivers in Taiwan were not regulated scientifically until the end of last century. Under the Japanese rule during a period of forty eight years from 1898 to 1945, a total of 419,153 meters of levee was completed with a corresponding protected area of 123,242 hectares, details of which are given in Table 1.
| Table 1. River Works Completed in the Period from 1898-1945 | ||||||
| Name of River | Length of Levee (meters) | Protected Area (hectares) | ||||
| Completed | Uncompleted | % of Completion | Corresponding to Completed levee | Corresponding to Uncompleted levee | Total | |
| I-Lan-Cho-Shui Creek | 42,790 | --- | 100 | 10,764 Taipeh district | --- | 10,764 |
| Tan-Shui River | 10,816 | 86,070 | 11 | 12,230 | 22,994 | |
| Tou-Chian Creek | 18,093 | 22,027 | 45 | 1,575 | 1,924 | 3,499 |
| Hou-Lung Creek | 7,268 | 18,487 | 28 | 557 | 1,432 | 1,989 |
| Ta-An Creek | 15,928 | 5,097 | 76 | 4,390 | 1,386 | 5,776 |
| Ta-Chia Creek | 10,073 | 8,547 | 54 | 1,552 | 1,319 | 2,871 |
| Wu Creek | 41,900 | --- | 100 | 4,775 | --- | 4,775 |
| Cho-Shui Creek | 76,273 | --- | 100 | 35,063 | --- | 35,063 |
| Pei-Kan Creek | 5,033 | 43,287 | 10 | 1,476 | 12,714 | 14,190 |
| Pu-Tzu Creek | 2,000 | 34,670 | 6 | 628 | 10,795 | 11,423 |
| Pa-Chang Creek | 4,514 | 35,786 | 11 | 1,478 | 11,959 | 13,437 |
| Chi-Shui Creek | 3,170 | 33,630 | 9 | 892 | 9,478 | 10,370 |
| Tseng-Wen Creek | 41,227 | --- | 100 | 24,628 | --- | 24,628 |
| Eth-Tseng-Hsing Creek | --- | 18,292 | 0 | --- | 110 | 110 |
| Hsia-Tan-Shui Creek | 78,046 | --- | 100 | 24,348 | --- | 24,348 |
| Ling-Pien Creek | 10,681 | 25,569 | 45 | 6,313 | 7,717 | 14,030 |
| Hua-Lian Creek | 7,711 | 26,009 | 23 | 1,588 | 5,316 | 6,904 |
| Hsiu-Ku-Luan Creek | 3,505 | 17,865 | 17 | 618 | 3,129 | 3,747 |
| Pei-Nan-Ta Creek | 5,640 | 16,220 | 26 | 737 | 2,097 | 2,834 |
| Feng-Shan Creek | 7,049 | 9,776 | 42 | 303 | 419 | 722 |
| Chung-Kan Creek | 3,029 | 6,621 | 31 | 365 | 814 | 1,179 |
| Tanapa Creek | --- | 11,060 | 0 | --- | 396 | 396 |
| Ta-Li Creek | 5,335 | 40,975 | 12 | --- | --- | --- |
| Yen-Shui Creek | 1,000 | 13,046 | 7 | 266 | 3,544 | 3,810 |
| A-Kong-Tien Creek | --- | 6,870 | 0 | --- | 5,071 | 5,071 |
| Tung-Kan Creek | 1,120 | 36,240 | 3 | 67 | 2,195 | 2,262 |
| Sha-Po-Tang Creek | 4,200 | 6,500 | 39 | 449 | 701 | 1,150 |
| Lu-Chia Creek | 1,446 | 9,414 | 13 | 375 | 2,513 | 2,888 |
| Chih-Pen Creek | 300 | 5,640 | 5 | 35 | 674 | 709 |
| Total | 419,153 | 537,698 | 123,242 | 97,933 | 221,175 | |
The origin of the irrigation works could be traced back as far as Yuan Dynasty (1291-1379) but was firmly founded and extended in Ming (1379-1665) and Tsing (1665-1911) Dynasties. During Japanese occupation, many improvements were made. In 1901, a regulation was promulgated for the administration of irrigation system under the supervision of the Japanese Government. Table 2 shows the general features of the area increased in the successive years from 1912 to 1944.
| Table 2 - Accumulating of Irrigated Area in the Period from 1912-1944 | ||||
| Years | Area Accumulated (hect.) | Area Increased (hect.) | Area Decreased (hect.) | Remarks |
| 1912 | 241,443 | -- | 1,252 | Area decreased due to damages not being recovered |
| 1913 | 240,191 | 5,693 | ||
| 1914 | 245,884 | 4,090 | ||
| 1915 | 249,974 | 4,486 | ||
| 1916 | 254,460 | 15,642 | ||
| 1917 | 270,102 | 16,723 | ||
| 1918 | 286,825 | 23,939 | ||
| 1919 | 310,764 | 3,973 | ||
| 1920 | 314,737 | 5,823 | ||
| 1921 | 320,560 | 4,307 | ||
| 1922 | 324,867 | 12,661 | ||
| 1923 | 337,528 | 5,868 | ||
| 1924 | 342,396 | 17,944 | ||
| 1925 | 361,340 | 20,744 | ||
| 1926 | 382,084 | 8,683 | ||
| 1927 | 390,767 | 9,549 | ||
| 1928 | 400,316 | 51,660 | ||
| 1929 | 451,976 | 3,193 | ||
| 1930 | 455,169 | 8,426 | ||
| 1931 | 463,595 | 118 | ||
| 1932 | 463,713 | 7,929 | ||
| 1933 | 471,642 | 3,906 | ||
| 1934 | 475,548 | 4,820 | ||
| 1935 | 480,368 | 20,305 | ||
| 1936 | 500,673 | 26,039 | ||
| 1937 | 526,712 | 16,961 | ||
| 1938 | 543,673 | 5,295 | ||
| 1939 | 548,968 | -- | 2,414 | Area decreased due to damages not being recovered |
| 1940 | 546,554 | 13,387 | ||
| 1941 | 559,941 | 2,058 | ||
| 1942 | 561,999 | No construction work in war time | ||
| 1943 | 561,999 | do. | ||
| 1944 | 561,999 | do. | ||
| Total | 561,999 | 324,222 | 3,666 | |
II. River and Irrigation Work since the Take-Over
River and irrigation works same to a standstill during World War II. Since the take-over of Taiwan and in view of the importance of hydraulic construction, damaged area has been thoroughly investigated, rehabilitation works have been effectively carried out. From October 1915 to July 1951, total length of levee repaired and newly constructed for the principal rivers ranges over 87,946 meters with 504 units of spur dikes. Besides, an additional length of 25,817 meters of levees for the secondary rivers have been repaired or built by different Hsiens or Municipalities under the auspices of the Provincial Government. As Taiwan is subject to violent typhoons and thunderstorms, many emergency works were constructed to reduce the damages thus created in these past years. Table 3, 4 and 5 given below show the amount of different kinds of river works completed since the take-over from Oct. 1945 up to July 1951.
| Table 3 - Amount of Flood Control Works Completed for the Principal Rivers Since the Take-Over | |||||||
| Years | Levee and Revetment (meters) | Spur dikes (unit) | Principal Materials and Labors Required | ||||
| Repairment | New Construction | Total | Cement (tons) | Galva. Wire (tons) | Labor (man-days) | ||
| 1945 | 4,404 | --- | 4,404 | 7 | 4,400 | --- | 424,126 |
| 1946 | 2,507 | --- | 2,507 | 4 | |||
| 1947 | 12,752 | 1,837 | 14,589 | 52 | 12,265 | 80 | 636,269 |
| 1948 | 22,769 | 2,731 | 25,500 | 104 | 20,565 | 304 | 1,451,896 |
| 1949 | 12,463 | 4,050 | 16,513 | 111 | 17,052 | 87 | 1,046,785 |
| 1950 | 10,397 | 2,365 | 12,762 | 98 | 2,933 | 1,506 | 891,586 |
| *1951 | 8,191 | 3,480 | 11,671 | 128 | 3,665 | 1,304 | not yet reported |
| Total | 73,483 | 14,463 | 87,946 | 504 | 60,880 | 3,281 | 4,450,662 |
| * Under construction; details subject to change. | |||||||
| Table 4 - Amount of Flood Control Works Completed for the Secondary Rivers by Local Hsien Governments under the Auspices of the Provincial Government Since the Take-Over | |||||
| Years | Repaired Length of Levees & Revetments (meters) | Spur dikes (units) | Remarks | ||
| 1948 | 8,300 | 4 | Under construction; details subject to change | ||
| 1949 | 4,159 | 15 | |||
| 1950 | 3,389 | 17 | |||
| 1951 | 8,969 | 39 | |||
| Total | 24,817 | 75 | |||
| Table 5 - Amount of Emergency Works Completed for the Principal Rivers Since the Take-Over | ||||
| Years | Damaged Levee (meters) | Emergency Works Completed | Remarks | |
| Levees & Revet's (meters) | Spur dikes (units) | |||
| Oct. 1945 | 33,243 | -- | -- | Before the take-over of Taiwan |
| 1946 | 14,457 | 1,854 | 7 | |
| 1947 | 25,199 | 17,662 | 98 | |
| 1948 | 5,847 | 27,075 | 105 | |
| 1949 | 1,953 | 4,638 | 48 | |
| 1950 | 4,664 | 918 | 16 | |
| 1951 | -- | -- | -- | Details not yet reported |
| Total | 85,363 | 24,817 | 274 | |
As to irrigation works, the Provincial Government takes charge of large-scaled projects for profited area over 500 hectares of cultivated land with well-irrigated or drainage system, while the local Hydraulic Association takes charge of small-scaled projects with profited area, below 500 hectares. In financing the large-scaled irrigation projects, the Government takes care of 50% of total engineering cost in western districts, with the other half taken by the local farmers who are entitled to the beneficial use of water. In eastern districts, farmers take care of only 30% of the total, the rest 70% being subsidized by the Provincial Government. For small-scaled irrigation projects, subsidy from the Government is only given to the construction cost of the structures. The proportion of the engineering cost to be taken care of by the Government and the farmers respectively is in the same manner as large-scaled irrigation project. That is, in western districts, half and half between the Government and farmers and in eastern districts, 70% for the Government and 30% for the farmers. Table 6 given below indicates the irrigated area increased, damaged and restored since the take-over. Table 7 shows the budget spent on both river and irrigation works these past years. It is obvious that despite financial difficulty, the Provincial Government has allocated each year a considerable percent age of its total budget for hydraulic construction purposes.
| Table 6 - Irrigated Area Increased, Damaged and Restored Since the Take-Over | |||||
| Years | Area Accumulated (hectares) | Area Increased (hectares) | Area Damaged * (hectares) | Area Restored (hectares) | Remarks |
| 1945 | 561,996 | 6,107 | 263,234 | 263,234 | |
| 1946 | 568,106 | 6,544 | 90,988 | 90,988 | |
| 1947 | 574,650 | 5,062 | 66,755 | 66,755 | |
| 1948 | 579,712 | 19,778 | 160,159 | 160,159 | |
| 1949 | 599,490 | 3,079 | 36,558 | 36,558 | |
| 1950 | 602,569 | 10,447 | 73,785 | 72,915 | |
| 1951 | --- | --- | 50,131 | --- | Not yet reported; damaged area included 870 hectares not being restored in 1950 |
| Total | 613,016 | 51,017 | 741,610 | 690,609 | |
| * Damaged area in each year refers to the area damaged in the preceding year. | |||||
| Table 7 - Budget for River and Irrigation Works Since the Take-Over | ||||
| Total Amount Spent on River Works | Total Amount Spent on Irrigation Works | |||
| Years | Paid in old Taiwan Dollars T. W. $ | Paid in New Taiwan Dollars N. T. $ * | Paid in old Taiwan Dollars T. W. $ | Paid in New Taiwan Dollars N. T. $ * |
| 1945 | 14,450,000 | 8,579,284 | ||
| 1946 | 78,350,000 | 34,802,950 | ||
| 1947 | 152,700,000 | 528,897,335 | ||
| 1948 | 3,082,000,000 | 1,457,776,000 | ||
| 1949 | 2,172,704.00 | 1,203,895.00 | ||
| 1950 | 16,061,030.00 | 14,138,970.00 | ||
| 1951 | 20,448,508.60 | 19,745,703.40 | ||
| New Taiwan Dollars has been adopted since June 1949. (N. T. $ 1 = T. W. $ 40,000) | ||||
III. Comparison: River and Irrigation Works Completed Before and After the Take-Over
Under the rule of the Japanese Government only 419,153 meters of levee had been completed from 1898 to 1945 and 320,556 hectares of cultivated land increased from 1912 to 1944, whereas since the take-over, up to July, 1951, a total length of 87,946 has been repaired and constructed and 51,017 hectares of land increased. Table 8 (A) and (B) give a comparison of the average constructed length of levee and average increase of irrigated area per year before and after the take-over.
| Table 8 - (A) Comparison of Length of Levee Completed Before and After the Take-over | ||
| Period Length | Total Length (m.) | Average Length per Year (m.) |
| Before the Take-Over (1898-1945) | 419,153 | 8,732 |
| After the Take-Over (Oct.1945 - July 1951) | 87,946 | 15,295 |
| Table 8 - (B) Comparison of Irrigation Area Increased Before and After the Take-over | ||
| Period Length | Total Area Increased (ha.) | Average Increased of Area per Year (ha.) |
| Before the Take-Over (1912-1944) | 320,556 | 9,428 |
| After the Take-Over (1945-1950) | 51,017 | 10,203 |
IV. Future Prospect of River and Irrigation Works in Taiwan
As to the very peculiar characteristic of Taiwan rivers, flood often causes serious damage and turns farmlands into barren wastes, if the rivers are not well trained. In fact, flood control and irrigation are closely related. Without the application of water on lands, where rainfall is short or unseasonable, there can be no further increase in the crop yield. It is, therefore, equally important to consider projects for flood control as well as those for irrigation. This leads to the planning and construction of storage reservoir for the multipurpose development. Even though the work of reservoir construction takes a considerable period of time and calls for a great amount of funds, it is still justifiable from the standpoint of power generation, irrigation developments and flood control works. Our main objective is that the water resources must be harnessed to the maximum extent for the maximum benefit of the maximum rivers in Taiwan.
***S. S. Chang (章錫綬) (Director, Water Conservancy Bureau, Taiwan Provincial Government.)