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Cokriging for evaluating agricultural pollution

Mullis, H.E. and Guitjens, J.C. and Robbins, C.W. (1989) Cokriging for evaluating agricultural pollution. pp. 127-135. In: Austin, T. Al (ed.) Proceedings of the American Society of Civil Engineers National Water Conference. USA-DE-Newark (Univ of Delaware), 1989/07/17-20.

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Agricultural irrigation is a major non-point
source polluter. Evaluating the extent of this type of
non-point source pollution requires sampling and analysis
of drainage waters. To reduce costs, sampling efficiency
is important. Cokriging can be used as a tool for
interpolating between sampling times or locations. In
this experiment, subsurface drainage data from irrigated
lands near Twin Falls, Idaho were used. Total Dissolved
Solids and NO3-N were selected as variables. The
objective was to determine if 50 and 65 percent of the
measured data could be removed (creating two new data
sets) and accurately estimated via cokriging using a
variogram model based on the remaining data. Cokriging
models were developed using statistical information
obtained from variograms of the remaining data. Once
accurate models were developed for both the 50 and 65
percent removal cases, estimations were made for the
missing data values. One-way analysis of variance and
t-tests were used to test whether the means and variances
of the estimated values were significantly different from
those of the measured values. At the 65 percent removal
level, there were significant differences in the means
and variances of the estimated and measured values for
NO3-N. One way analysis of variance and similarity of
variance tests were used to test whether differences
between the error values of the modeled and removed data
were significant. By using the unedited full set of
measured data for variogram modeling none of the tests
produced rejections.

Item Type: Conference or Workshop Item (Paper)
NWISRL Publication Number: 0682
Subjects: Mass Import - unclassified
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:57
Last Modified: 05 Jan 2017 18:50
Item ID: 1051