Comparison of Interpolation and Extrapolation Methods for Estimating Spatial Distribution of Annual Rainfall

Document Type : Original Article

Authors

1 Associate Research Prof.-Soil Conservation and Watershed Management Institute, Tehran, Iran

2 - Senior (Research) Scientist Soil Conservation and Watershed Management Institute, Tehran, Iran

Abstract

Estimation of spatial distribution of rainfall in different time scales is one of the basic steps in water resources studies. Problems in selection of proper methods for spatial variation of rainfall can produce error in input parameters of rainfall-runoff models in design or prediction stages. Also, reducing uncertainty in rainfall distribution is important in water budget studies. There are different methods for estimation of spatial distribution of rainfall based on raingage point data. Geostatistical methods are among such techniques. Geostatistical methods are favored in engineering studies since these methods consider spatial structure and location of data points. In this study, a number of methods were evaluated to estimate spatial distribution of monthly and annual rainfall in southwest of Iran. These methods consist of Thin Plate Smoothing Splines (TPSS), Weighted Moving Average (WMA) and Kriging. Cross validation technique was used for comparison of the methods. Results showed, although the TPSS method with power of 2 was marginally the most accurate method (with minimum MAE) in estimating annual rainfall but co-kriging method showed better consistency with topography of the study area. Analysis of variogram and error variance also demonstrated that generating missing data decreases accuracy of the interpolation.

Keywords

References

رحیمی بندرآبادی، سیما. (1379) "بررسی کاربرد روشهای ژئواستاتیستیک در برآورد بارندگی مناطق خشک و نیمه خشک جنوب شرق ایران". پایان نامه کارشناسی ارشد. دانشگاه تهران.
Abtew, W., J. Obeysekera, and Shih. G. (1993) "Spatial Analysis for Monthly Rainfall in South Florida". Water Resources Bulletin. 29(2): 179-188.
Goovaerts, P. (2000) "Geostatistical Approach for Incorporating Elevation into Spatial Interpolation of Rainfall". Journal of Hydrology. 228(1-2), pp.113-129.
Hargrove, W.W. (2001) "Interpolation of Rainfall in Switzerland Using a Regularized Splines with Tension". Geographic Information and Spatial Technologies Group, Oak Ridge National Laboratory.
Hohn, M. E. (1999) "Geostatistics and Petroleum Geology". Kluwer Academic Publishers. 248 pp.
Hutchinson, M.F. (1992) Splin A and LAPPNT. Center For Resource and Environmental Studies, Australian National University, Canberra, Australia.
Price, D.T., D.W. Mckinny, I.A. Nelder, M.F. Hutchinson and Kestevn. J.L. (2000) "A Comparison of Two Statistical Methods for Interpolation". Canadian Monthly Mean Climate Data. Agriculture and Forest. 101(2-3), pp. 81-94.
Tabios, G.Q. and Salas, J.D.  (1985) "A Comparative Analysis of Techniques for Spatial Analysis Precipitation". Water Resources Bulletin. (21)3, pp. 365-380.
Watson, G. S. (1984) "Smoothing and Interpolation by Kriging and with Splines". Mathematical Geology. 16(6), pp. 601-615.
Iran-Water Resources Research
Volume 1, Issue 2
July 2005
Pages 74-84

Files

History

  • Receive Date: 02 June 2004
  • Accept Date: 08 May 2005

Share

How to cite

Statistics