 |
| Titel |
Interpolation of groundwater quality parameters with some values below the detection limit |
| VerfasserIn |
A. Bárdossy |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 9 ; Nr. 15, no. 9 (2011-09-01), S.2763-2775 |
| Datensatznummer |
250012952
|
| Publikation (Nr.) |
 copernicus.org/hess-15-2763-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
| For many environmental variables, measurements cannot deliver exact
observation values as their concentration is below the sensitivity of the
measuring device (detection limit). These observations provide useful
information but cannot be treated in the same manner as the other
measurements. In this paper a methodology for the spatial interpolation of
these values is described. The method is based on spatial copulas. Here two
copula models – the Gaussian and a non-Gaussian v-copula are used. First a
mixed maximum likelihood approach is used to estimate the marginal
distributions of the parameters. After removal of the marginal distributions
the next step is the maximum likelihood estimation of the parameters of the
spatial dependence including taking those values below the detection limit
into account. Interpolation using copulas yields full conditional
distributions for the unobserved sites and can be used to estimate confidence
intervals, and provides a good basis for spatial simulation. The methodology
is demonstrated on three different groundwater quality parameters, i.e. arsenic, chloride and deethylatrazin, measured at more than 2000 locations in
South-West Germany. The chloride values are artificially censored at
different levels in order to evaluate the procedures on a complete dataset by
progressive decimation. Interpolation results are evaluated using a cross
validation approach. The method is compared with ordinary kriging and
indicator kriging. The uncertainty measures of the different approaches are
also compared. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|