Impact of Climate Change on Salinization in Iran

Iran is now faced with salinity problems in about 34% of its area in addition to harsh conditions of climate in about half of the country. To develop correlations between soil salinity and climatic factors, 1:1000000 soil salinity map of Iran and long term meteorological data were used in this study. Mean soil salinity shows fair correlations with different climatic variables developed as simple and multiple linear regression models (R2 of 0.56 to 0.72). Since predictors of these regression-based models consisted of different climatic variables, the General Circulation Model (GCM) - derived data were found suitable to link to the models for projection of salinity in upcoming decades. Data of HadCM3 model obtained from IPCC-SRES scenarios of A2 and B2 were used for projection of monthly Tmin, Tmax, annual precipitation and evapotranspiration for the next nine decades. Predicted variables were inserted in the developed regressions to project future status of soil salinity. At country wide scale, results showed that for the upcoming 90 years, mean soil salinity may increase from 1.5 to 4.7 dS/m, based on different scenarios and time intervals. This paper also describes importance of climatic factors in generation of Iran’s main playas in addition to special hydrologic, geologic, and topographic attributes of these regions. Results of this study revealed that playa’s climate will shift to harsher conditions, as a result of climate change. This fact was confirmed via simulation of the well-known aridity indices (including De Martonne and UNEP indices) for the next nine decades. This also signals that global climate change is likely to increase salinity of the main lakes, wetlands, lagoons and playas of the country. Therefore, strategies to mitigate climate change consequences should be planned and executed, especially in agricultural lands of arid and semi-arid regions of the country.