The Effect of Climate Changes on the Wetland Moisture Variations and Its Correlation with Sand-Dust Events in a Semiarid Environment, Northwestern Iran

Abstract

Climate change impacts on soil moisture have caused numerous environmental problems in different regions of the world, especially the arid and semiarid regions. The present study was carried out to examine the effect of climate change on soil moisture variations across a semiarid region of Iran, namely Meyghan wetland, using the multivariate regression. Mean Modified Normalized Difference Water Index (mMNDWI) was utilized to monitor soil moisture variations over the 28-year study period (1990–2017). The association between alteration in soil surface moisture (SM) and Dust Storm Index (DSI) was also explored using the bivariate regression method. Results showed that the area has experienced an increasing trend of soil moisture losses with a rate of 0.02 per 28 years. Increased wind velocity and decreased precipitation were recognized as the major driving forces in wetland degradation. The standardized regression coefficients for these factors were estimated at + 0.34 and − 0.28, respectively. However, no significant relationship was found between air temperature and evapotranspiration with mMNDWI. Based on adjusted determination coefficient (R2Adj), 75% of variations in soil moisture could be explained by rainfall and surface winds velocity changes across the study area. Our results showed that the ridge regression was able to show the dependence of mMNDWI variations on meteorological elements. It was also indicated that 23% of incremental changes in sand-dust events were due to wetland destruction. These findings provided a theoretical basis for understanding the climate change effects on soil moisture and the wetland degradation on dust emission over a semiarid region.