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ARS Home » Research » Publications at this Location » Publication #90425
Title: JUSTIFICATION OF AUTOMATED WATER TABLE CONTROL SYSTEMS

Author
item Fouss, James
item ROGERS, JAMES - USDA-ARS RETIRED

Submitted to: Irrigation and Drainage International Symposium Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Operation of water table management systems can be a difficult task in humid climate areas because of the erratic spatial and temporal distribution of rainfall. Monitoring of field water table depth between subsurface drainlines is an important parameter to properly adjust the drainage outlet water level in a timely manner to regulate subdrainage and subirrigation flows. The timing of adjustments needed is the major problem for farmers who attempt to operate these systems manually, and is especially acute in fine textured soils since frequent rainfall events can cause rapid and large fluctuations in water table depth. With an automated control system, water table depth is monitored frequently with a water level sensor, and the sensor output is used as a feedback signal to adjust automatically the outlet water level. A modeling/simulation approach is proposed to select and to evaluate the performance of an automated control system with given outlet options or constraints, and to determine the economic benefit (if any) by use of the system, based upon predicted improved crop response and yields. The method can be expanded to evaluate possible benefits of automated control in reducing losses of applied agrochemicals in runoff or subsurface drainage.

Technical Abstract: Operation of water table management systems can be a difficult task in humid climate areas because of the erratic spatial and temporal distribution of rainfall. Monitoring of field water table depth between subsurface drainlines is an important performance parameter to properly adjust the drainage outlet water level in a timely manner to regulate subdrainage and subirrigation flows. The timing of adjustments needed is the major problem for farmers who attempt to operate these systems manually, and is especially acute in fine textured soils with small drainable porosity (3 to 6%) since frequent rainfall events can cause rapid and large fluctuations in water table depth. With an automated control system, water table depth is monitored frequently with a water level sensor, and the sensor output is used as a feedback signal to automatically adjust the outlet water level. A modeling/simulation approach is proposed to select and to evaluate the performance of an automated control system with given drain spacing and outlet conditons, to determine the economic benefit (if any) by use of the system, based upon predicted improved crop response and yields. The method can be expanded to evaluate potential benefits of automated control in reducing losses of applied agrochemicals.