||Disjunctive Kriging as an Approach to Management Decision Making.
Yates, S. R. ;
Yates, M. V. ;
||California Univ., Riverside. Dept. of Soil and Environmental Sciences.;Robert S. Kerr Environmental Research Lab., Ada, OK.
Soil science ;
Decision making ;
Septic tanks ;
Ground water ;
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Disjunctive kriging is a nonlinear estimation technique that allows the conditional probability that the value of a spatially variable management parameter is greater than a cutoff level to be calculated. The method can be used in management decision making to help determine when some reclamation action is necessary. Two input parameters are required to use the technique: a cutoff level and the critical probability level. The use of disjunctive kriging as a decision making tool is illustrated using the regulation of septic setback distance as a means for minimizing the contamination of groundwater by viruses. Two examples are described: given a setback distance, the spatial distribution of the conditional probability that the virus concentration will be greater than acceptable levels is calculated; and given a critical probability level, calculating the spatial distribution of setback distances which satisfy that probability level. The study showed that, to be 90% confident that virus concentrations would be within acceptable limits, in many areas the setback distance would have to be severalfold higher than prescribed by current regulations.