Geology Reference
In-Depth Information
12
Applying Geostatistics: Basic
Knowledge and Variographic
Analysis with Exercises
P.S.N. Murthy, Tanvi Arora
1
and Shakeel Ahmed
1
Ex-Head, Geostatistics Centre & Gen. Manager, NMDC Ltd., Hyderabad, India
(Presently) Adviser, Essar Ltd., Visakhapatnam, India
1
National Geophysical Research Institute, Hyderabad-500007, India
INTRODUCTION
Any scientific study is based on a number of information on the system or
processes through measurement of parameters defining one or more properties
of the physical system. In most cases these parameters change their values
in space and sometimes in time also and hence they are called variables.
Rainfall, effective recharge, thickness of an aquifer, hydraulic head,
transmissivity, permeability, storage coefficient, etc. are the examples in
hydrogeology. Although, these parameters are often highly variables but this
spatial variability is not purely random and, according to Matheron (1963),
if measurements are made at two different locations, the closer the
measurement points are to each other, the closer the measured values. These
variables are given the name of Regionalized Variables (Re. V).
Although the characterization and estimation of a regionalized variable
(Re.V.) can be made on a purely deterministic basis, it is more convenient
and usual to introduce geostatistics in a probabilistic framework, bearing in
mind that this artifact is only a tool for performing an estimation (Marsily,
1986).
In this article attempt has been made to include a few basic aspects that
are often needed by a hydrogeologist to practise geostatistics and for others
it will be a refreshing starting from basic definition and formulae of statistics,
part of mathematics and algebra that are used.
