Jingtai Irrigation Scheme, P.R. China
In north-west China, the Jingtai Irrigation SchemeBa large-scale irrigation project which pumps water from the Yellow River to irrigate grain and other cropsBis divided into 2 phases, with Phase I complete in 1974 and Phase II complete in 1994. The design flow capacity is 28.6 cubic meters per second with an irrigated acreage approaching 66,700 hectares. The project encompasses an impressive group of pumping plants, aqueducts, lined canals, tunnels, etc.
The project has significant social and environmental benefits. Up to 1998, the project area had produced 2,030 million kg of grain and 661 million kg of oil seed with a total value of $32 million. With the project nearing completion, 400,000 people from surrounding mountainous areas have relocated to the project=s service area. Because of these secondary benefits, the national government pays a high percentage of the electrical costs of pumping the irrigation water.
Due to the complicated canal systems, project management is very difficult by conventional methods. It was noticed that the farmers at the head of canal had enough, even surplus water, but the farmers at the tail of the canal did not have enough water. The water using efficiency is low. It was proposed to test the low-cost automation technology at the key sites on the canal system to improve water management. In conjunction with the China Institute of Water Resources and Hydropower Research (IWHR) and the irrigation district, Reclamation staff has been consulting on two low-cost automation installations: (1) a 12-VDC (volts direct current) unit located on a major lateral, and (2) a trifurcation structure on a major canal. The equipment costs for both projects are shown in Table 3.
The 12-VDC demonstration site is installed on the head works for a major lateral. A lead-acid battery is used to power the gate actuator, telemetry equipment, and gate controller (CR10X datalogger). The gate actuator consists of a fractional horsepower 12-VDC gear motor attached to the gate=s gear box with chain and sprocket. A device to measure gate position and provide limit switches was also attached.
Table 1. Equipment Costs: Jungtai Irrigation Scheme Automation Demonstration Project
| Equipment | Costs ($US) | |
|---|---|---|
| Lateral | Trifurcation | |
| Datalogger/Controller | $1,100 | $1,100 |
| Telephone modem (w/voice) | 700 | 700 |
| Water-level sensor(s) | 1,000 | 2,200 |
| Gate-position sensor(s) | 600 | 1,800 |
| Gate-actuator(s) | 800 | *18,000 |
| Miscellaneous (enclosures, control panel, conduits, etc.) | 300 | 4,200 |
| TOTAL | $3,500 | $28,000 |
 | This site did not have the gearboxes and hoists installed on the radial gates; to make to costs comparable, the above table does not include these costs. |
The trifurcation structure is located at the terminus for a major canal. Here, the water is split to go three separate directions. The first split goes to a relift pumping plant, the second to a distant desert area that the irrigation district is currently developing, and the third directs water to adjacent irrigated lands. Because of the critical nature of the site, it was felt that automation was a necessity. Commercial gate actuators (Limitorque) were installed on the three radial gates. At this site, all the equipment (gate actuators, telemetry, and controllers) is powered by commercial power.
Communications for both demonstration sites are by land-line telephone. Low-cost dataloggers/controllers are used to monitor the state of the water delivery system and control the gates. The gate control software consists of a modified-PI algorithm. The water district has a choice of two control options: manual remote control or automatic remote control. With the first option they make gate movements, and with the second they set flow targets. The base station software being used is the software provided by the datalogger/controller manufacturer. The general configuration is shown in Table 2.