Yilan Irrigation Association is located at north-east of Yilan county, and nearby Pacific ocean in the east, Central Mountain Range in the north, west and south. As it is surrounded with mountains, Lanyang plain is delta under creation. Lanyang river passes through the plain from the west to the east and enters into the Pacific ocean. Suao-Hualien railroad is crossing from the south to the north. The elevation of this plain is below 100 meters and gradually lowers from the west to the east. The east land of railroad line is flat and the elevation under zero and belong to poor drainage area, about 4,000 ha. Therefore, Yilan Irrigation Association must manage well together the drainage and irrigation.
As this area is at rear of mountains and nearby the ocean to be affected by northeaster with mild climate, the annual average temperature is at 21.8 degree. It is a rainy season in the winter, and rainfall period is about 174 days. Annual average rainfall is about 3,000 millimeter, and relative humidity is 86%. In July, Aug., and Sept. of every year is dry period, and also is typhoon attack season. If no rainfall with the wind, then some areas will lack water. However, as its terrain is steep, the river is short and rapid flow into the sea.
The irrigation water resources intake from river, and “Main River” is Lanyang river, “Branches” include Lotung river, Yilan river, Wushih river, Tahu river, Tachia river, Hsiaochia river, etc. 6 rivers. Irrigation canals total: 150 canals. Drainage canal total 54 canals. Drainage in the territory is total 71 canals.
Irrigation pattern and cultivation way
According to the historical record of hydrology, etc. basic data, before every cycle of cultivation, irrigation plan for each canal shall be drafted and actual intake water must refer to the practical condition. Water delivered and managed by the responsible person in the working station to the irrigation area. As to the water distribution in the field, because this area is double-cropped for field cultivation, water supply for irrigation shall be taken in order with basic organization of irrigation group or team leader and members.