Analysis of SPI drought class transitions due to climate change. Case study: Kermanshah (Iran)

Abstract

Drought is a usual recurring climate phenomenon which happens almost all over the world. The present study investigates the effect of climate change on drought in Kermanshah (Iran). LARS-WG model was used in order to downscale the daily precipitation. Precipitation amount was estimated according to 3 scenarios, A₂, A₁B, and B₁ by HadCM3 global circulation model for 3 time periods in the future. SPI drought indexes were calculated regarding estimated precipitation for base time period and 3 future time periods, and drought class transitions were classified. Observed frequencies were calculated by creating 3-dimension contingency table in order to investigate drought class transitions. Drought classes in future time periods were compared to the base time period after calculating the odds ratio and confidence intervals. The comparison indicates that precipitation changes due to climate variability in the future will not cause any increase in moderate and severe/extreme drought frequencies.