This irrigation area is located in Yilan County, northeastern Taiwan, facing the Pacific Ocean to the east and surrounded by mountains in the north west and south adjacent to the northern tip of the Central Mountain Range. The terrain is like a delta alluvial fan plain and in the middle of the plain is the Lanyang River which flows from west to east into the Pacific Ocean. The North-Link Railway runs north to south, south to north. The plain is less than 100 meters above sea level and gradually decreases from west to east. The terrain at the east of the railway line is flat and about 5 meters above sea. Dezikou River and Dongshan River estuaries are mostly around 1.5 meters above sea level, and some of the terrain is even below zero. A low-lying area of about 4,000 hectares has poor drainage. As such, the operations of the office focuses on both drainage and irrigation management.
The area has mountains on one side, the sea on the other and is impacted by the northeast monsoon, with a mild climate and an annual average temperature of 21.8 degrees Celsius. The rainy season comes in winter, with about 174 rainy days per year, average annual rainfall of about 3,000 mm and relative humidity of about 86%. The dry season falls between July and September and is also the season when typhoons are most likely. Without the rain from typhoons the area would suffer from water shortages. Due to the steep terrain, short river flow and lack of reservoir facilities for storage and retention, river water runs off rapidly leading to river swells and floods. In recent years, the government has invested heavily to address regional drainage, including regulations on drainage systems such as Dongshan River, Meifu Drainage, and Dezikou River, as a result of which waterlogging problems in low-lying areas have eased.
Most of the office’s irrigation water comes from rivers. The main river is the Lanyang River which is administered by the central government, the scattered "tributaries" of the Yilan River, Wushi River, Dahu River, Dajiao River, Xiaojiao River and Luodong River, and other rivers including Dezikou River, Dongshan River, Xincheng River and Nan'ao River which are administered by the county. There are 150 water intake main canals; 54 main drainages and 71 drainage areas within the office’s jurisdiction.
Before each crop, the office drafts irrigation plans for each canal, based on basic information such as hydrological records with reference to previous flooding. Workstation management officers patrol and manage water delivery to the irrigation areas. In terms of field distribution operations, the grassroots irrigation team or group leaders and members take water in accordance with a predetermined order.