چكيده لاتين
This research was compiled with the aim of investigating the effects of global
warming and climate change on the climatic elements of temperature and
precipitation, with an emphasis on water resources in the Lanjanat sub-basin. At
first, the climatic changes in the region were investigated with the help of trend
analysis methods, and the temperature and precipitation trends in this sub-basin
were investigated. Non-parametric Mann-Kendall statistical method was used to
analyze the trend of time series of temperature and precipitation of the desired
stations in the area and vicinity of Lanjanat sub-basin in annual, seasonal and
monthly periods. Also, the Sen’s slope estimator was used to estimate the slope of
the trend line. The results of trend analysis on the time series of annual average air
temperature show a significant increase in air temperature in most of the stations
under study. So that in all the studied stations, the time series of the average
annual temperature has a trend at the significance levels of 99% and 95%. The
increase in temperature in the past years has had a negative impact on water
resources through increased evaporation and transpiration. On the other hand, the
increase in winter temperature has caused a decrease in the ratio of solid
precipitation to total precipitation, and in this way, sustainable feeding of
underground water sources has been challenged. The decrease in winter rainfall
and the consequent increase in precipitation in other seasons also confirm the
decrease in the ratio of solid precipitation to the total precipitation, and as a result,
the lack of effective and sustainable feeding of underground water resources. The
results of investigating the effects of precipitation on the river discharge indicate
that 93% of the annual changes in the Zayandeh Rood river discharge in the subbasin are explained by the annual variable of the sub-basin and upstream
precipitation. The results of the LARS-WG converter on the output of the selected
Earth system model, in the near future time periods of 2040-2021, 2060-2041
middle future and 2061-2080 far future for Lanjanat sub-basin, under different
climate change scenarios, indicate a decrease in annual rainfall by 5.7 to 7.5
percent in the period of 2040-2021, 5 to 8.2 percent in the period of 2060-2041
and 2.4 to 6.9 percent in the period of 2061-2080 compared to the base period.
These changes will decrease the average annual discharge of Zayandeh Rood by
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1.5 to 1.9 percent in the period of 2040-2021, 1.3 to 2.1 percent in the period of
2060-2041, and 0.6 to 1.8 percent in the period of 2080-2061. The annual
temperature forecast also indicates an increase in the average annual temperature
by 0.4 to 0.7 Celsius degrees in the period 2040-2021, 1.1 to 1.7 Celsius degrees
in the period 2041-2060, and 1.8 to 3.7 Celsius degrees in the period 2061-2080.
This increase in temperature will increase annual evaporation and transpiration by
2.8% to 3.3% in the period of 2040-2021, 4.9% to 6.9% in the period of 2060-
2041, and 6.8% to 13.4% in the period of 2080-2061 compared to the base period.
This increase in evaporation and transpiration will also have a negative impact on
the water resources of the region
