Climate change and reference evapotranspiration trends in Tehran

Climate change is one of the most pressing issues of our time, and its impacts are being felt around the world. In Tehran, Iran, extreme weather events related to climate change are becoming more frequent and severe. One of the factors that influence the water requirements of plants in Tehran is Reference Evapotranspiration (ET۰), which is a measure of the amount of water that is lost from the soil through evaporation and transpiration. The trends in reference evapotranspiration in Tehran are closely linked to climate change, and they provide important insights into the severity of extreme weather events in the region. The reference evapotranspiration in Tehran has been studied extensively in recent years, and the results show that there has been a significant increase in ET۰ over the past few decades. This increase is primarily due to rising temperatures, which are caused by climate change. As temperatures rise, more water is lost from the soil through evaporation and transpiration, which puts additional stress on plants and crops in the region. This can lead to reduced yields and even crop failure, which can have serious economic consequences for farmers and communities. In addition to the impact on agriculture, extreme weather events related to climate change can also have serious consequences for public health and safety. For example, heat waves are becoming more frequent and severe in Tehran, which can lead to heat exhaustion, heatstroke, and other heat-related illnesses. This is especially true for vulnerable populations such as the elderly and young children, who are more susceptible to the effects of extreme heat.One of the effective factors on the water requirement of plants is the Reference Evapotranspiration (ET۰), which is an important component of the hydrological cycle and is a function of climatic variables such as temperature, relative humidity, wind speed, and sunshine hours, which are influenced by climate change. In recent decades, climate change has become one of the human concerns and can be considered as the most important challenge of the recent century. Therefore, the aim of this study is to estimate and evaluate the trend of changes in reference evapotranspiration in Tehran city. For this purpose, the required data including daily statistics of maximum and minimum temperature, relative humidity, wind speed, and sunshine hours (۲۰۲۰-۱۹۷۶) from the Mehrabad synoptic station in Tehran were prepared, and missing data were reconstructed. Then, using the FAO Penman-Monteith ۵۶ method, reference evapotranspiration values were estimated for Tehran city. The results of the output of calculating reference evapotranspiration usingthis method indicated that the highest amount of reference evapotranspiration belongs to July with a maximum of ۳۱۳.۱, an average of ۲۶۹.۸, and a minimum of ۱۲۳ millimeters per month during the ۴۵-year period, which can be attributed to high air temperature, warm air currents, and high sunshine hours throughout the year. Overall, the results showed that although the trend of changes in reference evapotranspiration had significant fluctuations, it has been increasing in the long term, reaching its peak in ۲۰۱۷.In conclusion, extreme weather events related to climate change are becoming more frequent and severe in Tehran, and they are having serious consequences for agriculture, public health, and safety. The trends in reference evapotranspiration provide important insights into the severity of these events, and they highlight the urgent need for action to mitigate the impacts of climate change in the region.

کلیدواژه ها:

Environmental hazards ، FAO Penman-Monteith ۵۶ ، Mann Kendall ، Sen Slope ، Tehran