Temporal trends in precipitation using spatial techniques in GIS over Urmia Lake Basin, Iran

Precipitation trend analysis, on distinct spatial and temporal aspects, has been of great interest due to the increased attention given to global climate change by the hydro-climatological community. The aim of this study is: 1) to detect precipitation trends using the Mann-Kendall method in annual and monthly time scales at 42 stations in the Urmia Lake Basin (ULB); 2) to evaluate these detected trends in conjunction with the spatial interpolation techniques; namely, inverse distance weighting (IDW), ordinary Kriging (OK) and completely regularised spline (CRS) using GIS model. Results showed that both decreasing and increasing trends was observed at all time scales over the basin. Assessment of interpolation methods exhibited that the OK with an RMSE value of 1.14 was the best interpolation technique according to the cross-validation results. Briefly, the OK technique is concluded as the best method in the interpolation procedures based on the cross-validation and spatial clustering outcomes.