Geostatistical characterization of the transmissivity: An example of Kuwait aquifers

Abstract

Management of groundwater resources is critical to arid countries like Kuwait. One crucial information that is often not available to groundwater modelers is transmissivity of aquifers. Kriging is used to characterize the transmissivity of the two most commonly used aquifers in Kuwait (the Dammam and Kuwait Group aquifers). The transmissivity of the two aquifers is represented as a random spatial function where heterogeneity is described by the probability distribution and variogram of sample values. A structural analysis was performed which consisted of the construction and interpretation of sample variograms and the selection of model variograms to best fit the structure of the log-transformed transmissivity. The analysis indicated that the transmissivity of the Dammam aquifer is highly anisotropic and has a longer range of influence and larger variance (39 km; 333,487) than those for the Kuwait Group aquifer (10 km; 44,613). The model variograms were used in the kriging analysis to estimate the spatial average value of the transmissivity of the two aquifers in Kuwait. The estimated transmissivity of the Kuwait Group aquifer ranges from < 50 to about 800 m2 day-1, and is controlled principally by the thickness of the saturated zone in the aquifer. The estimated transmissivity in Dammam aquifer ranges from ~100 to 2200 m2 day-1, with high transmissivity fields coinciding with both the areas of major anticline and fault structures and the areas of aquifer recharge by fresh water, indicating the enhancement of the transmissivity on these structures by dissolution. Low transmissivity fields are located in the areas where the aquifer waters are stagnant. The performed analysis can be used to aid in the development of numerical models for sustainable management of the aquifer system in Kuwait, defining artificial recharge sites, and in optimizing the locations of future development wellfields.