Spatial Distribution of Groundwater Table in Hetao Irrigation District

Hetao irrigation district lies in the upper Yellow River, tha typical area of the plain which is characterized by drought. So the analysis of water balance factors such as water level is invaluable for understanding water cycle process. Geostatistical methods have been expanded to many other scientific fields for their unique statistical and interpolating advantages. In this paper, we applied ordinary kriging technique, one of the geostatistical methods, to analyze the spatial variability of annual water level ( groundwater tables) at 203 observation wells for this watershed during the period from 1997 similar to 2001. The result revealed that the semi - variograms of water tables were best described by spherical variogram model. The final parameters attained indicated that the range of every year presented geometry anisotropy. The maximal range, about 134 kin and minimal range, about 60km were from the search in the direction of 310 degrees and 40 degrees, respectively. In the meantime, studies indicated the existence of nugget effect in each year, which may be primarily caused by random factors at a spatial scale less than the range. After the analysis of water level data using kriging technique, the spatial distributions of mean annual water level were generated.