Evaluation of geo statistical techniques in drought intensity zoning (Case Study: Northwest and Central regions of Iran)

Drought is a natural phenomenon that periodically, every region and every climate, occurs in different sectors of human life can be affected by many negative effects. So far, the drought has many definitions. The lack of a comprehensive definition of drought and the different means, from a different perspective, the drought has hampered. For this purpose the quantitative expression of drought This phenomenon is used. This research proposes four characteristics of drought intensity, duration, and extent of occurrence of drought has been studied. To determine the extent of drought and its effects on different parts of the study area, indicators PNPI, MPNPI, DI and RAI in different parts of the draft Zoning calculated using ARC GIS software have been conducted. To achieve this goal, the statistics for 32 meteorological stations and synoptic polls that are doing good distribution in the region, 30-year period (from 1981 to 2010) were collected. Spatial distribution of drought indices using ground ordinary kriging (OK) and the spherical model, exponential, linear and Gaussian and inverse distance method (IDW) Batvan 1 to 5 were calculated, and the area classified drought done were. Then the method ground by using various criteria to evaluate and compare the RMSE and MAE. The results show that the ordinary kriging (OK) Gaussian model is more appropriate than the inverse distance method (IDW) and has a higher accuracy. It is recommended that this method be used for mapping regional drought.