Changhua County Public Legal Water Well Closure Plan (approved in 2006)

In order to plan measures to reduce the amount of groundwater pumping in large urban and rural areas, the Ministry of Economic Affairs and the Agricultural Committee of the Executive Yuan are taking the deep water wells located in Dacheng and rural areas owned by the Taiwan Sugar Company and Changhua Farmland Water Conservancy Association as the implementation targets. The implementation plan for the closure of publicly-owned legal water wells" aims to increase the water demand of the irrigation area under the jurisdiction of the ground water injection-related wells after the closure, and reduce the amount of groundwater pumping from the private wells of farmers, effectively alleviating soil compaction in large cities and rural areas, and preventing deeper development.
Background overview 
The irrigation area of ​​Changhua Farmland Water Conservancy Association can be divided into 4 irrigation districts, namely Changhua, Babao, Beidou and Nantou (Figure 1). Because the surface water source is insufficient for irrigation water demand, it was assisted by the Groundwater Engineering Division of the Construction Department of the former Taiwan Provincial Government in 1963. Begin to drill wells to develop groundwater resources as a supplementary water source during periods of insufficient surface water sources. Dacheng Township, Zhutang Township, Fangyuan Township, Erlin Township, etc., the main areas of stratum subsidence in southern Changhua, belong to the Beidou Irrigation District of Changhua Farmland Water Conservancy Association. This irrigation area is bounded by the old Zhuoshui Stream and the Zhuoshui Stream. The irrigation area is 17,804 hectares. The main origin is to draw water from Zhuoshui Creek for irrigation through the Yuzaibizhen, Yongji Erzhen, Yongji Sanzhen, Shengen Erzhen and Shengen Sanzhen for irrigation, and also draw the residual irrigation water that flows into the drainage road and the large cities and villages at the end of the irrigation. 19 wells and 1 well were dug in and Erlin Town respectively as a supplementary water source. Taiwan Sugar Company's business area in Changhua County is the only farming area (Figure 2) that belongs to Yong'an Farm, Xihu Raw Material Division, Huwei Sugar Factory, in Dacheng Township, Changhua County. The area is about 190 hectares. It mainly grows dry crop sugarcane and requires annual irrigation water. About 1.2 million cubic meters. The farming area is located in the irrigation area of ​​the Changhua Farmland Water Conservancy Association Dacheng Workstation. Due to the limited amount of surface water that can be allocated under the rotation irrigation system of the Water Conservancy Association, the main water source is the 3 groundwater wells in the farming area to extract groundwater supply. The annual water pumping volume is approximately 900,000 cubic meters.
Plan goal 
1. Achieve the "Changhua Yunlin Area Subsidence Prevention Plan" approved by the Executive Yuan for the closure and shutdown of 23 wells.
2. Increase the supply of surface water sources in large cities and rural areas of Changhua County and reduce the amount of groundwater pumping for irrigation.
3. Slow down the downward trend of groundwater level in Dacheng Township, Changhua County, and ease the rate of stratum subsidence in the township.
Perform work  
1. Changhua Farmland Water Conservancy Association:
1. 20 water wells are installed with water measuring equipment and the sealing is out of service
2. Improvement works for the bottleneck section of the north shore communication channel
3. New pumping station in the lower reaches of Zhuoshui River
(1) Overhaul and renovate the existing temporary water blocking weir at the old water intake of Yongji Sanzhen and the 7-kilometer water diversion road to facilitate the introduction of water from Zhuoshui River.
(2) It is planned to set up a pumping station in the original water intake embankment of Zhuoshui River, including equipment such as water collection well and operation machine room.
4. Expansion of connection channels
5. A new pump is installed in the drainage road to extract the return water
6. Detailed design planning
2. Taiwan Sugar Company:
3 Wells were installed with water measuring equipment in 2007 to strengthen their water metering management; after the completion of this part of the project in 2007, the three wells will be closed and shut down and must be properly maintained and maintained for future drought periods The emergency water source for emergency deployment, but the Taiwan Sugar Company must consider the water source scheduling situation and apply to the water rights authority (Changhua County Government) before it can be used after approval. It is estimated that the cost of installing water measuring equipment for each well is NT$60,000, and the total cost of 3 wells is NT$180,000.
2. In conjunction with the Changhua Farmland Water Conservancy Association's new pumping project in Yuliao Creek, Taiwan Sugar Company will bury an 8-inch PVC underground connecting pipeline 250 meters between the pumping pump and the existing aqueduct, and lead the pumped water to the existing aqueduct.
3. In line with the new water source measures of the Changhua Farmland Water Conservancy Association, the Taiwan Sugar Company introduced the Changhua Farmland Water Conservancy Association's 960-meter canal water source for deep cultivation of the Erzhen water source, and cooperated with the Water Conservancy Association's regional rotation irrigation system to draw and allocate water to the cultivated area for irrigation .
4. In order to improve the water use efficiency of the cultivated area, the existing canal and road leaking water loss improvement project was implemented, and the irrigation branch canal was renovated into a U-shaped trench with a length of 1,200 meters.
Expected results
In addition to reducing the annual pumping volume of about 4.1 million cubic meters of water from wells under the jurisdiction of Changhua Farmland Water Conservancy Association and Taiwan Sugar Company in Dacheng and rural areas, a complete irrigation water supply network can be constructed to improve Xizhou Township, Pito Township, Zhutang Township and Erlin With good surface water supply conditions for irrigated farmland in the town’s irrigation area, and improving the stability of water supply, it will reduce the demand for underground water pumping by private wells in each irrigation area, which will help the area's groundwater level rise and stratum subsidence relief.
(Approved by the Executive Yuan's Yuantaijingzi No. 0950004345 on February 3, 2006)