The pointwise SWI values are then spatially interpolated in GIS environment using the ordinary
kriging method and ArcGIS 10.2 software to find out the areal extent of drought in the study area.
The other method of interpolation used to generate drought intensity surface was Inverse Distance Weighted (IDW) and
Kriging with Gaussian semivariogram (Figure-2 and 3).
In order to interpolate TDS parameter used IDW, RBF and Ordinary
Kriging methods.
We used a land-use, mixed-effects regression model developed with readily available data (air quality and meteorological monitoring data, road networks information, latitude) and two spatiotemporal interpolation models: a) a combined land-use BME model incorporating both [O.sub.3] monitoring station data and the land-use mixed model outputs (BMELUR), and b) a
kriging method based only on available data from [O.sub.3] monitoring stations (BME
kriging).
The most commonly used methods of interpolation in geographic information systems (GIS) are inverse distance weight (IDW) (Buchanan and Triantafilis, 2009; Sun et al., 2009), spline (Varouchakis and Hristopulos, 2013; Buchanan and Triantafilis, 2009) and
Kriging (Pokhrel et al., 2013; Sun et al, 2009; Yang et al., 2008).
This paper presents an effective optimization method based on
Kriging metamodel.
Kriging is a geostatistical estimation method which can be considered as the best unbiased estimator.
Co-Kriging is a multivariate enhancement to the geostatistical method of
Kriging [7], that attempts to build an approximation of a function that is expensive to evaluate, through coupling cheap low fidelity data (auxiliary) with a small amount of high fidelity data (primary) [13].
Univariate
kriging methods including ordinary
kriging and universal
kriging have been widely applied to environmental science, natural resources, remote sensing, and GIS.
Keywords: Water quality, Water quality index, Effective weights, Empirical bayesian
kriging, Ordinary
kriging, Principal component analysis.