Comparison of precise water depth measurements on agricultural storages with open-water evaporation estimates

Craig, I. P. (2006) Comparison of precise water depth measurements on agricultural storages with open-water evaporation estimates. Agricultural Water Management, 85 (1-2). pp. 193-200. ISSN 0378-3774

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Abstract

[Abstract]: A simple technique to determine evaporation and seepage losses of agricultural water storages is described. Evaporation is calculated from Automatic Weather Station (AWS) variables using the Penman-Monteith equation, and seepage is determined as the difference between this and accurate water depth measurements made using a Pressure Sensitive Transducer (PST). The accuracy of the PST devices (1mm) was far greater than any flow metering equipment available, so analysis only took place when there was no pumping in and out of the dam. Calibration tests were carried out during the summer of 2004/5 at a dam site where seepage was very close to zero, as total evaporation plus seepage loss over the winter months there was independently determined to be less than 1mm/day . Summertime PST depth traces were compared to the Penman 1948 equation, Penman-Monteith (PM) ETo calculated according to the FAO56 method and Penman-Monteith (PM) with surface resistance set to zero to simulate a open water surface. The first two produced the best correlations (within 10% agreement with the water depth trace), but PM open water over predicted by 40%. This technique has provided a useful tool to more accurately apportion total water loss into evaporation and seepage components. Similar to the evapotranspiration of different crop types, it is suggested that that the evaporation of open water can be similarly related to the international standard FAO56 PM via a simple dam factor.

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Item Type:	Article (Commonwealth Reporting Category C)
Refereed:	Yes
Item Status:	Live Archive
Additional Information:	Copyright 2006 Elsevier: Reproduced in accordance with the copyright policy of the publisher.This is the author-version of the work. It is posted here for your personal use. Use the hypertext links above to access the journal's website.
Depositing User:	Dr Ian Craig
Faculty / Department / School:	Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited:	11 Oct 2007 00:37
Last Modified:	27 Sep 2016 04:38
Uncontrolled Keywords:	evaporation, Penman Monteith, pressure sensitive transducer, seepage
Fields of Research :	09 Engineering > 0914 Resources Engineering and Extractive Metallurgy > 091499 Resources Engineering and Extractive Metallurgy not elsewhere classified 09 Engineering > 0905 Civil Engineering > 090509 Water Resources Engineering
Identification Number or DOI:	doi: 10/1016/j.agwat.2006.04.010
URI:	http://eprints.usq.edu.au/id/eprint/1244

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