Estimating Precipitation Data Using a Fuzzy-based Technique

Document Type : Original Article

Authors

Assistant Professor Water Engineering Department, Ferdowsi University of Mashhad

Abstract

As a flexible tool that may be adapted to many systems, fuzzy logic was employed to develop a new technique for estimation of precipitation data. This fuzzy-based technique estimates precipitation for any point upon available data from the neighboring meteorological stations. The contributions of each station is weighed due to its differential longitudes, latitudes, and altitudes with respect to the point of interest. This was accomplished through two membership functions for distance and elevation. Each of these functions are composed of four fuzzy sets (triangular and trapezoidal shapes with partial overlaps), which in turn led to sixteen fuzzy rules. Computing weights for each station activates a minimum of two and a maximum of four rules. The technique was tested for Khorasan province in eastern Iran using the data from 48 meteorological stations. Finally, the results from the fuzzy-based technique are compared with the results of two other commonly used methods, namely simple average and inversed-distance. The results generally showed the minimum error for fuzzy technique. The minimum mean-absolute-error and the model deviation of the estimated values were found for the fuzzy-based technique. Inversed-distance and simple average methods showed higher values for these parameters. The role of the number of stations involved in the estimation process was also discussed. The optimal number of stations are found to be four.

Keywords

References

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Iran-Water Resources Research
Volume 6, Issue 1
July 2010
Pages 39-47

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History

  • Receive Date: 18 August 2007
  • Accept Date: 21 November 2009

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