Effects of land use changes on local dust event in Urmia Lake basin

Abstract

Land use change is an effective factor in climate change and global warming, which contributes to the carbon cycle, radiant energy balance, and dust production. Urmia Lake basin water balance in the Northwestern part of Iran is in a critical condition due to land use change, drought, and climate change. This process has led to the lake water area reduction and pronounced dust production. The satellite images indicate that from 1984 to 2017, 1433 Km² rangelands and water area of the Urmia Lake basin decreased by more than 2906 Km². The area of human settlement increased by 550 Km², irrigated farmland and orchards, 804 Km², and salty marsh, 3428 Km². The outputs of the WetSpass hydrological model reveal the highest coefficient of evapotranspiration and interception variation in the East of Urmia Lake basin. The effects of these changes are observed in reduced soil moisture, increased salty marsh, and soft sediments as potential dust resources. During the study period, the frequency of dust days in the North and East of the lake increased 2.5-fold, while in the Southern and Western parts increased 6-fold. The results of the Pettitt Test indicate that these changes began to appear in 2007. The regression and correlation test confirm that salt marshes and soft sediments account for up to 75 %, and the decrease in the area of Urmia Lake for more than 64 % of the dust changes. The results of the assessments indicate the contribution of footprint in the destruction of the natural environment and the water balance of the lake basin. Revision of water resources management and environmental water rights of the lake, changes in the development strategy from agriculture to non-agriculture development based on lower water demand, and reduction of storage dams are among the recommended strategies to address this problem.