REAL-TIME SOIL WATER MONITORING FOR OPTIMUM WATER MANAGEMENT1

Authors

  • Ali Fares,

    1. Respectively, Associate Professor of Hydrology, Research Associate, and Assistant Researcher, Natural Resources and Environmental Management Department, University of Hawaii-Manoa, 1910 East-West Road, Honolulu, Hawaii 96822; Visiting Assistant Professor, Civil Engineering Department, Suleyman Demirel University, Isparta, 32260, Turkey; and Extension Specialist, Tropical Plants and Soil Science Department, University of Hawaii-Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822 (E-Mail/Fares: AFares@Hawaii.Edu).
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  • H. Hamdhani,

    1. Respectively, Associate Professor of Hydrology, Research Associate, and Assistant Researcher, Natural Resources and Environmental Management Department, University of Hawaii-Manoa, 1910 East-West Road, Honolulu, Hawaii 96822; Visiting Assistant Professor, Civil Engineering Department, Suleyman Demirel University, Isparta, 32260, Turkey; and Extension Specialist, Tropical Plants and Soil Science Department, University of Hawaii-Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822 (E-Mail/Fares: AFares@Hawaii.Edu).
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  • Viktor Polyakou,

    1. Respectively, Associate Professor of Hydrology, Research Associate, and Assistant Researcher, Natural Resources and Environmental Management Department, University of Hawaii-Manoa, 1910 East-West Road, Honolulu, Hawaii 96822; Visiting Assistant Professor, Civil Engineering Department, Suleyman Demirel University, Isparta, 32260, Turkey; and Extension Specialist, Tropical Plants and Soil Science Department, University of Hawaii-Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822 (E-Mail/Fares: AFares@Hawaii.Edu).
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  • A. Dogan,

    1. Respectively, Associate Professor of Hydrology, Research Associate, and Assistant Researcher, Natural Resources and Environmental Management Department, University of Hawaii-Manoa, 1910 East-West Road, Honolulu, Hawaii 96822; Visiting Assistant Professor, Civil Engineering Department, Suleyman Demirel University, Isparta, 32260, Turkey; and Extension Specialist, Tropical Plants and Soil Science Department, University of Hawaii-Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822 (E-Mail/Fares: AFares@Hawaii.Edu).
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  • Hector Valenzuela

    1. Respectively, Associate Professor of Hydrology, Research Associate, and Assistant Researcher, Natural Resources and Environmental Management Department, University of Hawaii-Manoa, 1910 East-West Road, Honolulu, Hawaii 96822; Visiting Assistant Professor, Civil Engineering Department, Suleyman Demirel University, Isparta, 32260, Turkey; and Extension Specialist, Tropical Plants and Soil Science Department, University of Hawaii-Manoa, 3190 Maile Way, St. John 102, Honolulu, Hawaii 96822 (E-Mail/Fares: AFares@Hawaii.Edu).
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  • 1

    Paper No. 05148 of the Journal of the American Water Resources Association (JAWRA) (Copyright © 2006). Discussions are open until June 1, 2007.

Abstract

Abstract: Efficient water resource management is one of the most important policy issues facing agriculture in Hawaii in the years ahead. Soil water sensors, multisensor capacitance probes (MCP), have been successfully used for different water management projects. These MCPs monitor water content at multiple depths and at various locations in real-time. The objectives of this study were to determine the effect of water content on field soil bulk density of Wahiawa silty clay tropical soil; measure field saturated hydraulic conductivity of this tropical soil: calibrate MCP system for this soil: and monitor and evaluate real-time soil water content variations under a tomato crop using the calibrated MCP system. Sensor calibration was conducted under laboratory conditions. Soil bulk density at different water contents and saturated hydraulic conductivity were measured on the field. Bulk density increased with increasing water content: there was a 30 percent bulk density increase as a result of 0.25 cm3 cm-3 water content variation. Compared with the manufacturer's calibration, site specific laboratory calibration of MCP gave a more accurate determination of soil water. Field determined saturated hydraulic conductivity was higher than laboratory determined values reported in the literature for the same soil type. Real-time soil water content monitoring within the root zone showed substantial variations due to water input (irrigation and rainfall) and water output (evapotranspiration and deep percolations). However, water content variations were much further reduced in the soil layer below the root zone.

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