Climate Change Effects on Soil Freezing Depth in a Mountainous Region and a Semi-Arid Climate on the Malayer Plain

Soil freezing depth is an important parameter in the management of soil water availability in agriculture and horticulture. The purpose of this study was to investigate the effect of global warming and climate change on the freezing depth by using different scenarios on the Malayer Plain, which is the center of grape and raisin production in the country. Daily minimum and maximum air temperatures, sunshine hours, and precipitation data were collected from the Malayer Synoptic Station from 1995 to 2013 and used to simulate the near future climate using the HADCM3 and LARS-WG models based on the optimistic, pessimistic, and moderate scenarios. Performances of these models were evaluated by comparing observation and simulation data using the R2, NSE, RMSE, and MAE indices. The results showed that these models have the necessary efficiency to predict the production of daily data in the region. The air freezing index was estimated by using the Norwegian, Finnish, and American methods based on the mean daily air temperature. Soil freezing depth was estimated by the McKeown and Standard model based on the soil texture at different depths and air temperatures .Annual precipitation, maximum and minimum temperatures will rise under the three scenarios A1B, A2, and B1. The air temperature will increase in winter more than the other seasons, while the absolute value of minimum temperature changes will be higher than that of the maximum temperature. The RSME and CRM indicators in the base and future periods indicate that the Norwegian method, and more, than that the Finnish method, are suitable for estimating the soil freezing depth (at the 5% level) in this semi-arid and mountainous Zagros Region. Application of this method overestimates a deepe freezing depth for the future. Due to the climate change, the depth of freezing will be reduced by the end of 2030 in this important agricultural plain.