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| Titel |
A decision tree model to estimate the value of information provided by a groundwater quality monitoring network |
| VerfasserIn |
A. I. Khader, D. E. Rosenberg, M. McKee |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 5 ; Nr. 17, no. 5 (2013-05-08), S.1797-1807 |
| Datensatznummer |
250018872
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| Publikation (Nr.) |
 copernicus.org/hess-17-1797-2013.pdf |
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| Zusammenfassung |
| Groundwater contaminated with nitrate poses a serious health risk to infants
when this contaminated water is used for culinary purposes. To avoid this
health risk, people need to know whether their culinary water is
contaminated or not. Therefore, there is a need to design an effective
groundwater monitoring network, acquire information on groundwater
conditions, and use acquired information to inform management options. These
actions require time, money, and effort. This paper presents a method to
estimate the value of information (VOI) provided by a groundwater quality
monitoring network located in an aquifer whose water poses a spatially
heterogeneous and uncertain health risk. A decision tree model describes the
structure of the decision alternatives facing the decision-maker and the
expected outcomes from these alternatives. The alternatives include (i)
ignore the health risk of nitrate-contaminated water, (ii) switch to
alternative water sources such as bottled water, or (iii) implement a
previously designed groundwater quality monitoring network that takes into
account uncertainties in aquifer properties, contaminant transport
processes, and climate (Khader, 2012). The VOI is estimated as the difference
between the expected costs of implementing the monitoring network and the
lowest-cost uninformed alternative. We illustrate the method for the Eocene
Aquifer, West Bank, Palestine, where methemoglobinemia (blue baby syndrome)
is the main health problem associated with the principal contaminant
nitrate. The expected cost of each alternative is estimated as the weighted
sum of the costs and probabilities (likelihoods) associated with the
uncertain outcomes resulting from the alternative. Uncertain outcomes
include actual nitrate concentrations in the aquifer, concentrations
reported by the monitoring system, whether people abide by manager
recommendations to use/not use aquifer water, and whether people get sick
from drinking contaminated water. Outcome costs include healthcare for
methemoglobinemia, purchase of bottled water, and installation and
maintenance of the groundwater monitoring system. At current
methemoglobinemia and bottled water costs of $ 150/person and
$ 0.6/baby/day, the decision tree results show that the expected cost of
establishing the proposed groundwater quality monitoring network exceeds the
expected costs of the uninformed alternatives and there is no value to the
information the monitoring system provides. However, the monitoring system
will be preferred to ignoring the health risk or using alternative sources
if the methemoglobinemia cost rises to $ 300/person or the bottled water
cost increases to $ 2.3/baby/day. Similarly, the monitoring system has
value if the system can more accurately report actual aquifer concentrations
and the public more fully abides by manager recommendations to use/not use
the aquifer. The system also has value if it will serve a larger population
or if its installation costs can be reduced, for example using a smaller
number of monitoring wells. The VOI analysis shows how monitoring system
design, accuracy, installation and operating costs, public awareness of
health risks, costs of alternatives, and demographics together affect the
value of implementing a system to monitor groundwater quality. |
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