The irrigation working area under the jurisdiction of the office is located in the central part of Taiwan, adjacent to the Central Mountain Range in the east, bounded by Maoluo River, a tributary of Wu River, and adjacent to Changhua Management Office in the southwest, and bounded by Caohu River in the north, next to Taichung Management Office and a tributary of Wu River, nurturing the mountainous and culturally rich land. The area is mountainous, with various mountain landscapes and pleasant scenery so there are many sightseeing resources. Due to the different elevations in the area, ranging from 50 meters to 750 meters above sea level, there is a considerable difference in terrain and the riverbed is narrow. Torrential rain in summer causes the water to flow fast, which can result in serious damage to the water intake and greatly increase maintenance costs. The climate is mild all year round, rainy and abundant in water in summer, while in winter there is little rainfall and a shortage of water. Annual average rainfall is 1,731mm, and the average rainfall from May to September is 1,433mm, accounting for about 82.2% of the annual rainfall.
(1) Irrigation water source: the main irrigation water source used by the office is surface water, which is under the river water intake type and easily impacted by seasonal water sources. When the river water source is insufficient or the water intake cannot direct water due to disasters during the cultivating period for single crop fields, groundwater wells are used as a supplementary water source, and water blocking gates set up in the regional drainage to recycle water for irrigation, to promote the effective reuse of water resources. Surface water sources can be divided into two major water systems: 1. Wu River water system: total of 68 canals such as Nenggao Canal, with an irrigated area of 12,675 hectares, accounting for 95.72%. 2. Zhuoshui River water system: 6 canals, such as Xincheng Canal, with an irrigation area of 567 hectares, accounting for 4.28%.
(2) Irrigation channels: There are 74 irrigation channels under the jurisdiction of the office. The main channels are: Beitouxin Canal, Longquan Canal, Jialaomazhu Canal, Azhaowu Canal and Nenggao Canal.
(3) Drainage channels: The main drainage channels under the jurisdiction of the office include Chelongpi Drainage, Houxidi Drainage, Xixinba Drainage, Xiweiliao Drainage, Pipacheng Drainage, Diaoxuegou Drainage, Chaofengpi Drainage, Niulugou Drainage, Dapi Drainage and Xizhoupi Drainage. There are 10 drainage channels in total with a water shed area of 3,282 hectares and a permissible drainage capacity of 847.59cm.
The office has an irrigated area of 13,242 hectares and its cultivating fields include double cropped fields with an area of 12,684 hectares and single cropped fields with an area of 558 hectares. Within the area, there are 30 rice seedling days for the first crop and 20 for the second crop, 25-30 days for field preparation for the first crop and 25 days for the second crop. There are 110-120 field irrigation days for first crop and 90-102 for the second crop. Field irrigation rate (unit ha/CMS), field preparation 48.0, growing field 470 to 720.