ISSN 1058-3912
Vanita Agnihotri and Shakeel Ahmed
National Geophysical Research Institute
Hyderabad, India
ABSTRACT
Ambiguities in the data collection network design mainly based on the
geostatistical estimation variance reduction method have been analyzed
using a few numerical examples. The method of locating new measurement
points with the help of an estimation variance (also called kriging variance)
map has an ambiguity on the number of new data collection points, and hence
does not provide an optimal network. The method of optimizing measurement
points by reducing estimation variance at the central point of the considered
area has an ambiguity that the same network will be valid for an even much
larger area, if the center remains unchanged. In the examples considered
it was found that the kriging variance calculated for an estimation over
the entire area/block increases if the area/block is increased keeping
the center of the area unchanged for the same network. However, a few ambiguities
were found while considering an area whose center point was also shifted
with the origin. The exercise was repeated by arbitrarily adding some new
data collection points to the considered network. Further, the method of
estimating the mean of the parameter by ordinary kriging was applied to
calculate the kriging variance for different networks. Although the ambiguity
that the same network representing different areas remains, this method
provides a comparatively lesser kriging variance.
Reference: Agnihotri, V. and S. Ahmed; Analyzing Ambiguities
in the Data Collection Network Design by Geostatistical Estimation Variance
Reduction Method, Journal of Environmental Hydrology, Vol. 5,
Paper 5, August 1997.