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Taiwan Joint Irrigation Association
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Taiwan's Farmland Irrigation Environment and Resources

Natural Environment

With a total area of nearly 36,000 sq. km, the island of Taiwan is sectioned into two distinguished parts by the Central Mountain Range; eastern Taiwan is characterized by long and narrow gorges, and western Taiwan, vast plains. Taiwan has an oceanic and subtropical monsoon climate; it's greatly affected by the seasonal exchange of air masses between the continent and the ocean.

Hydrology and Climate

  • Climate:
  • Taiwan has an oceanic and subtropical monsoon climate, summers are long and accompanied by high humidity, making the plains the ideal place to grow crops. The northeast monsoon lasts from October to late March; the summers and falls see storms and torrential rains causing severe damage and bringing abundant rainfall.

  • Hydrology:
  • The mean annual rainfall in the Taiwan area is 2,510 mm, but the distribution of water resources in Taiwan is uneven, both in time and space, with nearly 80 percent of precipitation falling between May and October. Heavy rains packed by typhoons often wrecked havoc on crops. To alleviate the damage, data is collected with 915 rainfall observation stations and 134 discharge observatories set up around the island at strategic hydrological footholds to monitor changes and variation.

  • Rivers:
  • The Central Mountain Range serves as the watershed for Taiwan's many rivers, which originate here flow in easterly and westerly direction into the ocean. 29 primary rivers provide water for irrigation, and many of them were short and steep, becoming torrential during heavy rainstorms. Water flow drops during the dry season, water for irrigation is therefore used to support public and industrial water consumption. During flood seasons the frail geology in upriver and narrow, steep riverbeds cause floods to pour down bringing large quantity of silts, making them difficult to manage and develop as water resources.

Water Resources Management

Taiwan's annual average rainfall stands at 90.5 billion cubic meters. The annual water consumption is 17.6 billion cubic meters, accounting for 19 percent of the annual rainfall. In which agricultural water use stands at 12.4 billion; household use, 3.5 billion, and industrial use, 1.7 billion cubic meters. Other water resources include 8.7 billion cubic meters of river runoff, 5.4 billion cubic meters of underground water, and 3.5 cubic meters of reservoir water.

Land Development Projects

With Taiwan's total area at 3.6 million hectares, 9 hundred and 50 thousand of them are inland plains, 9 hundred and 70 thousand hectares, foothills; and 1.68 million hectares, high mountains. The arable lands were measured originally at 1 million hectares; but most of them were adapted to industrial use. The government therefore opened up 13 thousand some hectares of lands reclaimed from the river, and more than 43 hundred hectares of polders, with arable lands at 8 hundred 70 thousand hectares. Among which Irrigation Associations own 3 hundred 78 thousand hectares; and another 100 thousand hectares are privately owned.

To promote maximal utilization of farmlands, the government adopted a versatile, multi-purpose land reform tactics – the rezoning of farmlands. So far 75 percent of the rice paddies have been completed, with the feasibility of dry land rezoning being researched at the moment.