Application and evaluation of universal kriging for optimal contouring of groundwater levels
Tóm tắt
This paper deals with the application of universal kriging to interpolate water table elevations from their measurements at random locations. Geographic information system tools were used to generate the continuous surface of water table elevations for the Carlsbad area alluvial aquifer located to the southeast of New Mexico, USA. Water table elevations in the 38 monitoring wells that are common to 1996 and 2003 irrigation years follows normal distribution. A generalized MATLAB® code was developed to generate omni-directional and directional semi-variograms (at 22.5° intervals). Low-order polynomials were used to model the trend as the water table profile exhibits a south-east gradient. Different theoretical semi-variogram models were tried to select the base semi-variogram for performing geostatistical interpolation. The contour maps of water table elevations exhibit significant decrease in the water table from 1996 to 2003. Statistical analysis performed on the estimated contours revealed that the decrease in water table is between 0.6 and 4.5 m at 90% confidence. The estimation variance contours show that the error in estimation was more than 8 m2 in the west and south-west portions of the aquifer due to the absence of monitoring wells.
Tài liệu tham khảo
ASCE Task Committee 1990a Review of geostatistics in geohydrology I: Basic concepts; J. Hydraul. Eng. ASCE 116 612–632.
ASCE Task Committee 1990b Review of geostatistics in geohydrology II: Applications; J. Hydraul. Eng. ASCE 116 633–658.
Bjorklund L J and Moths W S 1959 Geology and water resources of the Carlsbad area Eddy County, New Mexico; New Mexico Office of the State Engineer, Open file report, 59(9).
Dunlap L E and Spinazola J M 1984 Interpolating water-table altitudes in west-central Kansas using kriging techniques; USGS Water-Supply Paper 2238, United States Government Printing Office, Washington.
Gundogdu K S and Guney I 2007 Spatial analyses of groundwater levels using universal kriging; J. Earth Syst. Sci. 116(1) 49–55.
Hale W E 1961 Geology of groundwater in New Mexico; New Mexico Office of the State Engineer, Open file report, 61(13).
Igúzquiza E P and Olmo M C 2004 Estimation of gradients from sparse data using Universal Kriging; Water Resour. Res. 40(12) W12418.
Isaaks E H and Srivastava R M 1989 Applied Geostatistics (New York: Oxford University Press).
Johnston K, Ver Hoef J M, Krivoruchko K and Lucas N 2001 Using arc GIS-geostatistical analyst; GIS by ESRI, Redlands, USA.
Journal A G and Huijbregts C J 1978 Mining Geostatistics (London: Academic Press).
Kastelec D and Koŝmelj K 2002 Spatial interpolation of mean yearly precipitation using universal kriging; Developments in Statistics 17 149–162.
Kumar V 2007 Optimal contour mapping of groundwater levels using universal kriging – a case study; J. Hydrol. Sci. 52(5) 1039–1049.
Kumar V and Ramadevi 2006 Kriging of groundwater levels – a case study; J. Spatial Hydrol. 6(1) 81–94.
Pucci A A and Murashige J E 1987 Applications of universal kriging to an aquifer study in New Jersey; Ground Water 25(6) 672–678.
Rouhani S 1989 Geostatistics in water resources; Proceedings of the Georgia Water Resources Conference, The University of Georgia, Georgia, 169–171.