A Comparative Analysis of Water Quality Sampling Decisions in Aquifers

No single set of sampling decisions is optimal for all monitoring programs. Cost-effective decisions will have to be made in an adaptive framework, constantly changing yet having a basic structure. The major objectives of this paper are to develop and illustrate such a model structure for groundwater quality sampling decisions. Sampling decisions are shown to be governed by an interplay of qualitative and quantitative factors such as the specificity of stated objectives, the level of desired precision in estimates, ,md the quasi-objective method of estimating health effects of contaminants. These findings are illustrated with five optimization models, of varying complexity, for sampling decisions in two aquifers. Over 50 years of groundwater quality data on selected constituents from two contrasting aquifers, the shallow Quaternary and the deep Cambro-Ordovician, in Iowa are used to test, illustrate, and evaluate model performance. Several avenues for further research are also outlined.