Review of the Kriging Technique Applications to Groundwater Quality

Kriging, a geostatistical technique, has been used for many years to evaluate groundwater quality. The best estimation data for unsampled points were determined by using this method depending on measured variables for an area. The groundwater contaminants assessment worldwide was found through many kriging methods. The present paper shows a review of the most known methods of kriging that were used in estimating and mapping the groundwater quality. Indicator kriging, simple kriging, cokriging, ordinary kriging, disjunctive kriging and lognormal kriging are the most used techniques. In addition, the concept of the disjunctive kriging method was explained in this work to be easily understood.

Pemodelan Permukaan Digital Data Magnetik Survei Geofisika Udara menggunakan Metode Geostatistika untuk Ekplorasi Mineral (Daerah Studi: Wilayah Komopa, Papua)

ABSTRAKDalam interpretasi data, data hasil survei geofisika udara umumnya perlu diubah menjadi model permukaan digital atau digital terrain model (DTM). Hal ini sebagai langkah untuk memudahkan dalam memahami kondisi data secara keseluruhan. Untuk membuat DTM banyak metode yang dapat diterapkan. Salah satu di antaranya adalah dengan metode Geostatistika Kriging. Penerapan metode Geostatistika Kriging dapat menggunakan berbagai macam teknik di antaranya adalah teknik Simple Kriging dan Disjunctive Kriging. Dalam penelitian ini dilakukan pengolahan DTM untuk data magnetik dengan menggunakan kedua teknik ini dengan aproksimasi Gaussian Kernel dan Density Skew. Wilayah studi pada penelitian ini adalah wilayah Komopa, Kabupaten Painai, Provinsi Papua yang merupakan wilayah Kontrak Karya PT. Freeport Indonesia. Adapun data yang digunakan adalah data hasil survei geofisika udara yang dilakukan pada periode 1983-1984. Hasil pemodelan yang diperoleh dari kedua teknik tersebut selanjutnya dibandingkan dan diperoleh hasil bahwa teknik Disjunctive Kriging dengan aproksimasi Density Skew lebih baik daripada teknik Simple Kriging dengan aproksimasi Gaussian Kernels maupun Density Skew.Kata kunci: survei geofisika udara, magnetik, DTM, geostatistika, krigingABSTRACTIn data interpretation, airborne geophysical survey results generally need to be transformed into a digital terrain model (DTM). This is an effort to facilitate in understanding the condition of the whole of data. To make the DTM, many methods can be applied. One of them is Kriging geostatistical method. Application of Kriging geostatistical method can use various techniques such as Simple Kriging and Disjunctive Kriging technique. In this research DTM processing for magnetic data has been performed by using both of these techniques with Gaussian Kernel and Density Skew approximation. The study area in this study is the area of Komopa, Painai District, Papua Province which is the area of Work Contract of PT. Freeport Indonesia. The data used is the data of airborne geophysical survey conducted in the period 1983-1984. The modelling results from the two techniques were then compared and the results showed that the Disjunctive Kriging technique with Density Skew approximation is better than Simple Kriging techique with Gaussian Kernels and Density Skew approximation.Keywords: airborne geophysical survey, magnetic, DTM, geostatistics, kriging