This irrigation association is located in the central south of west coast in Taiwan, and in the east, connecting to Chenyoulan stream of Nantou county, and west part of Central Mountain range, in the west, facing to the Taiwan straits, starting the limitation from Chuoshui stream in the north and Santieh stream of Chiayi county in the south.
In the territory, the annual rainfall is averaged at 1,500 mm, and that is rich with uneven distribution in time and space. It is a rainy period from May ro October, occupying 80% of whole year rainfall. From November to April of next year, it is dry period, occupying 20%. As the sand content in this irrigation area is high to be 4/1000, it is very easy to result in blockade in canal and the maintenance is difficult to do. Administrative areas cross over Chiayi, Yunlin, and Nantou three counties, including 20 towns and cities.
1. Irrigation water resources – Because there is no reservoir in this territory, the irrigation water supply resources is extremely unstable. After Chichi dam gate was completed in 2000, it had a great help to stabilize the water supply for Chuoshui river and to function for the water regulating. At present, the irrigation water resources in irrigation are are:
a. Surface water: comes from Chuoshui river, Chingshui river, and Peikang river, Huwer river, etc. natural river flow.
b. Ground water: comes from well digging and power pumping , total 584 wells.
c. Supplemental water resources: makes use fo irrigation system and ditches, ponds, and spring zone to pump water for recycle use. There are 71 pumping stations with facilities in the irrigation area.
2. Irrigation canals – Chuokan canal, Touliu canal, Hsinhuwei canal, Luchangko canal, Jiana canal, and Chichi canals, etc. total 11,109 canals with overall length of 7,467,258 meters.
3. Drainage canals – There are 12,645 drainage canals facilities, large drainage 90 canals, medium drainage 751 canals, small drainage 11,804 canals, with overall length 6,587,028.
Irrigation pattern and cultivation way
1. Irrigation system – The main irrigation water resources in this territory comes from Chuoshui river, Chingshui river, and belongs to river flow type. As the water supply resources is extremely unstable, the supplement water resources is developed by well digginh to pump water for irrigation. However, for the limitation of shout and torrential rivers, the water quantity is unable to be sufficient for irrigation. Therefore, in this territory, most of the farmlands maintain a rotary cultivation under operation.
2. Cultivation way – is divided into double- cropped cultivation, single-cropped cultivation, two years-one crop cultivation, and three years-one crop cultivation, etc.