An ivestigation on spatial and temporal variations of groundwater level in Kerman plain using suitable geostatistical method (During a 10-year period)

Due to the variation of ground water properties in temporal and spatial scale, these properties can not be assumed constant over time and space. This research was conducted to assess spatial and temporal variations of ground water table in Kerman plain during a 10-year period (1375-1385) by using the best geostatistical estimator. Firstly, available statistical resources related to the ground water table of this plain (including 67 wells) were collected. After controlling for quality, accuracy and normality of the data, different interpolation techniques were used including kriging (with and without logarithm), cokriging, inverse distance (with exponents of 1 to 5). The best technique was selected based upon MAE and MBE criteria and provided spatial zonation maps in the beginning and end of the period. Spatial zonning maps were prepared at the beginning and end of the study and ultimately, iso-falling map was provided in Arc GIS 9.1 package. Our findings showed that Gaussian variogram model was the best for spatial structure of these data and inverse distance method with exponents of 5 and 4 were the best interpolation methods in the beginning and end of the period, respectively. Zonation maps showed a falling trend of the ground water level in majority of the plain. Maximum falling data (32 meters), was recorded respectively for the northern outlet of the plain with an effective range of 17 and 62 pizometers and western outlet with an effective range of 8 pizometers. Also, the results showed an upward trend of water, as 7 meters, in effective range of some wells with 50 and 52 pizometers in Kerman city due to being located in sewage and waste water zone of the city.