Selecting the Best Method of Interpolation to Annual Precipitation Zonation in Iran

The meteorological variables required in the management of water resources are valid only for measuring points and to assess them in places without data، interpolation method should be used. The present research was done to investigate the best method of spatial interpolation to estimate the annual average precipitation in Iran. To do that، data of 180 synoptic stations was used. Then، using different deterministic interpolation methods (IDW، GPI، LPI and RBF) with different powers (1،2،3،4،5) and different models (Completely Regularized Spline، Inverse Multiquadric، Multiquadric، Spline with Tension، Thin Plate Spline) and geostatical interpolation methods of kriging and co-kriging were used to investigate the temporal pattern of average annual precipitation and identify the best method for interpolation of annual participation in Iran. The results showed that among the deterministic interpolation methods، the RBF method and Spline with Tension have the least RMSE and the most correlation. Finally، among the deterministic and geostatical methods، using reciprocal evaluation method and RMSE، MBE، MAPE and R indices، method for interpolation was selected the best providing the annual precipitation map in Arc GIS (using kriging).