The irrigation area under the jurisdiction of the office is located in the western part of Taiwan, bounded by Dadushan terrace, and divided into two irrigation zones, one is the Taichung Basin between the eastern foothills of Dadushan terrace and the Central Mountain Range; the other area is on the coastal plains including Dadu, Qingshui, Dajia, Yuanli etc. between the western foothills of Dadushan terrace and the west coast. The geology within the area, including in Yuanli, Houli, Xinshe, Dadu shan is laterite, while the geology in areas including Dajia and Qingshui is sandy gray soil, with the rest loam and sandy loam.
The main sources of irrigation water are from the Da'an River, Dajia River and Wu River. All three originate in the Central Mountain Range. During the dry season, groundwater is pumped to supplement water sources. Except for Damaopu Canal and Dadu Canal, which are irrigated with pumped groundwater, the other canals are directly irrigated with retained dam river water. After the office was founded, the old irrigation and drainage channels were inspected, actively improving and maintaining various irrigation facilities while also replacing manual operations. The irrigation water sources within the jurisdiction are mainly from branches and tributaries of Da'an River, Dajia River, and Dadu River. Some irrigation areas use return flow for irrigation.
The irrigation pattern in the area under the jurisdiction of the office is double cropped irrigated by river diversion. The main irrigation water sources are Da'an River, Dajia River and Wu River. The fields are mainly first crop and second crop double cropped fields with rice as the main crop. Paddy fields account for 84% of the whole planted area and dry crops (or fruit) are mainly plated in upland fields in the Danan, Dongshi and Zhuolan areas. The fields are rice first crop fields, inter crop fields, rice second crop fields and post second crop fields, though there has been a clear decrease in post second crop fields, with the inter crop fields and post second crop fields mostly fallow land. The irrigation schemes adopted by the office are continuous irrigation, large area rotation irrigation and small area rotation irrigation.