The increase in population and as a result the increase in land use changes and excessive exploitation of underground water resources have not only caused a decrease in the quantity but also caused the destruction of the quality of these valuable resources. Therefore, it is necessary to eva‎luate and investigate the role of land use and surface temperature on underground water resources in different areas. In this regard, the role of thermal islands and land use on the quantity and quality of underground water in the Yazd-Ardakan plain has been examined in the current research. For this purpose, first, land use maps, moisture index (NDMI), vegetation index (NDVI) and heat islands (LST) using Landsat 5, 7 and 8 images with a spatial accuracy of 30 meters in 2005 and 2010, 2015, 2020 and 2023 were prepared in order to examine the process of changes more closely. The land use maps showed that in 2023, the percentage of city and pasture land use increased by 1.05% and 13.52% respectively compared to 2005, but the use of barren land, orchards, and agriculture increased respectively it has decreased by 3.61, 0.1, 10.86 percent compared to 2005. The maps of heat island changes showed that in 2005 the maximum and minimum temperatures are 63.15 and 0.77 degrees Celsius, while in 2023 the maximum and minimum temperatures are 60.05 and 14.37 degrees respectively it was found that in 2023 the maximum temperature has decreased compared to 2005 and the average temperature has increased. The maps of NDMI changes also showed that in 2005 the maximum and minimum NDMI is 0.34 and -0.24 respectively, while in 2023 the maximum NDMI is 0.31 and the minimum NDMI is -0.30 that in 2023, the maximum and average NDMI will decrease compared to 2005. The maps of NDVI changes also showed that in 2005 the maximum and minimum NDVI is 0.40 and -0.07 respectively, and in 2023 the maximum NDVI is 0.46 and the minimum NDVI is -0.16 in 2023, the maximum NDVI increased compared to 2005 and the average NDVI decreased, but it did not differ much compared to 2005. Therefore, in terms of vegetation, 2005 has a weaker situation than 2023. Finally, Pearson's correlation was taken between land use changes and quantitative and qualitative parameters of underground water and between temperature changes and quantitative and qualitative parameters of underground water. In general, it can be said that the increase of agricultural, garden and urban land has been effective in reducing the level of underground water. Also, in agricultural, garden and urban uses, especially in recent years, the concentration of most water quality parameters including; Anion, cation, calcium, chlorine, electrical conductivity of water, bicarbonate, potassium, sodium, absorption ratio of sodium and dissolved solids in water have increased and caused a decrease in underground water quality. The results of the correlation between temperature changes and quantitative and qualitative parameters of underground water also showed that the increase in temperature had a significant effect on the decrease of the underground water level during the statistical period, and also the increase in temperature had a significant effect on the increase in the concentration of anion parameters, chlorine, water and potassium electrical conductivity. According to the obtained results, it can be stated that thermal islands and land use have influenced the quantity and quality of underground water in Yazd-Ardakan plain.

9/15/2024 12:00:00 AM

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