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Applied Geostatistics http://www. geog. buffalo. edu/~lbian/GEO497_597
Applied Geostatistics GEO 597 Spring 2012 Instructor: Ling Bian T R 11:00-12:20pm, 144 Wilkeson Office: 120 Wilkeson Office Hours: T R 11-12:20pm
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What is it The course is intended to introduce the basic concepts and applications of applied geostatistics, which address optimal spatial interpolation.
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What is it … Geostatistics are considered to be one of the most sophisticated spatial interpolation methods. The method is commonly used in many disciplines such as geology, engineering, hydrology, geography, ecology, urban studies, and medical geography. Geostatistics are closely related to statistics and GIS.
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What is it … Students with basic knowledge of statistics or GIS can take a step further to learn how to use geostatistics. The course emphasizes the applied side of geostatistics, and the method can be useful in students' immediate and future needs such as students' own theses and dissertations, or projects for their current or potential employers.
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What is it … The course uses a well received textbook for the lectures and a popular GIS software package ArcGIS for the lab exercises. Three lab sections and assocated assignments will provide students with hands-on experience in using the geostatistical tool.
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Text An Introduction to Applied Geostatistics. Oxford University Press, New York, by Isaaks, Edward.H., and R.Mohan. Srivastava, 1989. The “Ed and Mo” book
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Prerequisites The course is open to graduate students who have knowledge of univariate statistics. Multivariate will help but is not required.
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Requirements During the semester, each student should apply the geostatistical interpolation to a data set. Past students’ projects
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Requirements A term paper
Introduction Literature review Study area Data and methods (incorporate the labs, plus…) Results and discussion conclusions around 15 double-spaced pages of text, plus tables, figures, references
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Grading Lab 1 10% Lab 2 10% Lab 3 10% Project Report 70%
Total %
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Grad cut-off A 93.33-100.0 A- 90.00-93.32 B+ 86.67-89.99 B 83.33-86.66
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Tentative Schedule 1/17 Introduction 1/19 Spatial Description 1/26 Spatial Description 1/31 Spatial Continuity 2/ 2 Spatial Continuity 2/ 7 Estimation 2/ 9 Random Function Models 2/14 Random Function Models 2/16 Lab section 1
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Tentative Schedule … 2/21 Global Estimation 2/23 Point Estimation 2/28 Ordinary Kriging 3/ 1 Ordinary Kriging 3/ 6 Block Kriging 3/ 8 Search Strategy 3/ Spring Break
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Tentative Schedule … 4/ 3 Co-Kriging 4/ 5 Co-Kriging
3/20 Cross Validation 3/22 Modeling the Sample Variogram 3/27 Lab Section 2 3/29 Lab Section 3 4/ 3 Co-Kriging 4/ 5 Co-Kriging 4/10, 12 Advanced Topics 4/17,19,24 Presentations 4/26 Conclusion
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Software ArcMap Geostatistics Analyst
ESRI tutorial for Geostatistical Analyst
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1. Definition A procedure of estimating the values of properties at un-sampled sites The property may be interval/ratio values The rational behind is that points close together in space are more likely to have similar values than points far apart
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2. Terminology Point/line/areal interpolation point - point, point - line, point - areal
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2. Terminology … Global/local interpolation
Global - apply a single function across the entire region Local - apply an algorithm to a small portion at a time
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2. Terminology … Exact/approximate interpolation
exact - honor the original points approximate - when uncertainty is involved in the data Gradual/abrupt
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3. Interpolation - Linear
Linear interpolation Known and predicted values after interpolation Known values
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3. Interpolation - Linear
Assume that changes between two locations are linear
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3. Interpolation - Proximal
Thiesson polygon approach Local, exact, abrupt Perpendicular bisector of a line connecting two points Best for nominal data
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3. Interpolation - Proximal
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3. Interpolation – Proximal ..
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3. Interpolation – B-spline
Local, exact, gradual Pieces a series of smooth patches into a smooth surface that has continuous first and second derivatives Best for very smooth surfaces e.g. French curves
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3. Interpolation – Trend Surface
Trend surface - polynomial approach Global, approximate, gradual Linear (1st order): z = a0 + a1x + a2y Quadratic (2nd order): z = a0 + a1x + a2y + a3x2 + a4xy + a5y2 Cubic etc. Least square method
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Trends of one, two, and three independent variables for polynomial equations of the first, second, and third orders (after Harbaugh, 1964).
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3. Interpolation – Inverse Distance
Local, approximate, gradual S wizi 1 z = , wi = -----, or wi = e -pdi etc. S wi dip
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3. Interp – Fourier Series
Sine and cosine approach Global, approximate, gradual Overlay of a series of sine and cosine curves Best for data showing periodicity
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3. Interp – Fourier Series
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3. Interp – Fourier Series
Single harmonic in X1 direction Two harmonics in X1 direction Single harmonic in both X1 and X2 directions Two harmonics in both directions
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3. Interp - Kriging Kriging - semivariogram approach, D.G. Krige
Local, exact, gradual Spatial dependence (spatial autocorrelation) Regionalized variable theory, by Georges Matheron A situation between truly random and deterministic Stationary vs. non-stationary
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3. Kriging First rule of geography:
Everything is related to everything else. Closer things are more related than distant things By Waldo Tobler
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3. Interp - Kriging Semivariogram 1 n g(h) = S (Zi - Zi+h)2 2n i=1 Sill, range, nugget Sill Range Lag distance (h) Semivariance
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3. Kriging Isotropy vs. anisotropy
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4. Summary Statistics Parameters (for populations) m, s2, s
Statistics (for samples), x, S2, S
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4. Basic Statistics Measures of location mean, median, mode, minimum,
maximum, lower and upper quartiles Measures of spread variance, standard deviation Correlation covariance, correlation coefficient
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