The irrigation area under the jurisdiction of the office is located in the southwest area of southern Taiwan, adjacent to Pingtung County in the east, the Taiwan Strait in the southwest, and Tainan County in the north, connecting sea, mountains and plains. The irrigation area covers 28 townships and cities in Kaohsiung County and Kaohsiung City, and is roughly divided into three irrigation zones: Caogong, Gangshan, and Qishan; including plains and terraces in the three zones, which are widely distributed on the southern bank of Erren River, Agongdian Reservoir, the north bank of Gaoping River, Laonong River and Qishan River basins.
The irrigation area is located between longitude 120 degrees, 10 minutes, 16 seconds and 120 degrees, 38 minutes, 05 seconds east, and north to south between latitude 22 degrees, 30 minutes and 03 seconds and 23 degrees, 42 seconds. The climate is warm and sunny throughout the year, with a minimum temperature of 9.6-11.5 degrees Celsius and a maximum temperature of 36.4-36.9 degrees Celsius; Average annual rainfall over the past 10 years is 1,845mm. Although rainfall is abundant, the rainfall period is concentrated between June and August, with about 1,199mm, accounting for 65% of total annual rainfall. In addition, because the land is adjacent to the ocean and there are no mountains to provide cover, typhoons are frequent. The rainy season is prone to floods and the dry season is long. As such, the annual effective rainfall that can be directly used is only about 459 mm. As for the soil in the irrigation area, the Fengshan, Gangshan and Qishan plains are all fault geology in addition to the alluvial sand and sandy soil along the Qishan River, Anong River and Gaoping River. In terms of soil distribution, sandy loam is the largest, accounting for 37%, followed by loam with 32%, clay soil 18%, sandy soil 12%, and sandy gravel soil 1%, making it generally suitable for agriculture.
The office’s main water sources are surface water and groundwater. Total annual water consumption is about 379.67 million cubic meters, of which surface water accounts for 96.82% and groundwater for 3.18%. The main water sources come from Gaoping River, Laonong River, Qishan River, Erren River, Agongdian Reservoir, Dianbao River, Houjin River, Guanyin Lake, a few ponds, groundwater or recycled water. The main irrigation water source in Caogong area is Gaoping River, the main irrigation water sources in Gangshan area are Erren River and Agongdian River Reservoir. The main irrigation water sources in Qishan area are mainly Laonong River, followed by Qishan River, and Qishan River is the main drainage source.
- Irrigation scheme: Workstations draft irrigation plans for each canal to send to the office for approval based on cropping patterns and surveys of the irrigated area, with reference to basic requirements and information on regional hydrology, climate, geographical environment and diversified agricultural characteristics. Those plans are sent to workstations to implement water delivery, water irrigation distribution and patrol management, so as to more effectively control the water resource utilization according to each plan. In the case of severe drought and water shortages, in addition to pumping groundwater or recycling water to supplement the surface water shortage, other measures include executing large-area rotation irrigation, adopting seven-day or nine-day rotation irrigation, and executing corresponding water resource regulation depending on the degree of water shortage and water demand of crops, to minimize losses due to the drought.
- There are two categories of cultivating fields within the irrigation area: rice fields and miscellaneous crop fields. Annual irrigation is divided into two phases, with the first crop cultivated from early January to late May, and the second crop from early June to late October. In the off-peak water consumption period for rice crops, depending on the amount of water consumption in the current period for irrigation, and after considering such factors as time, place and amount, the water is used to irrigate miscellaneous crops such as sugarcane, bananas, corn etc. The inter crop is cultivated between the first crop and the second crop and irrigated by rainwater or self-developed water sources using self-owned small water pumps, and the main crop is melons. The post second crop is cultivated between late November and mid-December, with 20 days of water irrigation and requires flexible allocation depending on the situation of ongoing annual repair constructions. The main crops are tobacco leaves, beans and vegetables.