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Rainfall and interpolation techniques
Hamid Reza Rezaei Javid
khajenasir University and IWPCO(Iran Water Power co.,
Iran
Email: h.javid@iwpco.com or hr9617@yahoo.com
Rainfall measurements are commonly measured at point locations and these values are required by Hydrologists and Engineers to be converted to a raster format. The most common method that is used is the Inverse Distance Weighting interpolation technique. This technique uses the location and magnitude of the rainfall to determine estimates of rainfall at unmeasured locations.
Khuzestan province located at southern Iran has an areal extent of approximately 65924 square kilometers. Daily rainfall is measured, at approximately 62 locations in Khuzestan. Areal estimates of daily rainfall have an importance especially in water-poor regions such as southern Iran. Many big projects such as Masjedsoleiman and Karkhe dams are being constructed and researchers often require an estimate of rainfall at ungauged points. All the points of the region are determined in order for researchers to assess the spatial distribution of the rainfall.
In this paper proving the present areal structure depends on both distance and direction dimensions with use of variogram and covariogram tools on rainfall stations, the best method for interpolation through out the geostatistical methods is Simple Kriging. Another result was that after proving the relation between rainfall and elevation, using both DEM and Cokriging methods is recommended when lack of rainfall distribution measurements stations is observed in order to interpolate the rainfall.
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