آسيب پذيري اقليمي منابع آب حوضه آبخيز خوانسار

This research aims to investigate the effects of global warming and climate change on the elements of temperature and precipitation, with an emphasis on water resources in the Khansar watershed. The present research is applied in terms of purpose and its method is analytical, based on documentary studies. To examine the hypotheses and answer the questions, geostatistical techniques and synoptic data of the region have been used. In this research, using geostatistical methods (descriptive, inferential statistics), in addition to examining data testing with statistical methods and time series analysis (moving average), the trend of temperature and precipitation data (parametric) and non-parametric Mann-Kendall have been used. Regarding the collection of relevant information, the documentary library method (books, articles and the Internet) has been used, and the documentary method (using recorded statistics from meteorological stations) has been used for collecting information to eva‎luate the study area, and the statistical and GIS methods have been used for analysis. The present research will be conducted at the level of analysis. For this purpose, the level of analysis eva‎luated in this study is the Khansar watershed area, and precipitation data from the regionʹs stations in a statistical period (1993-2023) were used. In this study, the anomalies of temperature and precipitation changes during the statistical period are compared to standardized data with mean and standard deviation. The standard statistical distribution method Z (Gossin) was used to calculate the temperature and precipitation anomaly. In this method, while calculating the difference of each time period with the long-term average, its ratio with the measured standard deviation is calculated, and positive values (increase) and negative values are considered as negative (decrease) anomalies. To examine the temperature changes in the study area, the Khansar station was used. (This variable is recorded at the Khansar station) The non-parametric P-Test test was used to analyze temperature changes. This test is used to identify trend changes. The results show that the minimum temperature of the region has significant changes. At the 95% confidence level, the p-value statistic is = 0.05 and the year of its changes is 2004. The test result shows an increase of 1.4 degrees Celsius from 2004 to 2020. This rate of temperature increase in a 16-year period is very high. It is far from the global average (the 200-year average is about 1.3 degrees Celsius). In addition, this increase in temperature has severe hydrological effects in the mountainous region of Khansar. Annual data and the statistical period (1993-2023) have been used to calculate and determine the precipitation anomaly at the stations of Khansar, West, Rahmatabad, Qodjan and Doushkharat. According to the graphical diagram, at the beginning of the statistical period, annual precipitation shows higher values with positive anomalies. In other words, from the beginning of 1990 to 1997, precipitation with positive anomalies has a higher frequency than at the end of the time series. Since 2009, the frequency of precipitation with negative anomalies has been higher. From this anomaly, it can be concluded that the region has experienced drier years compared to the beginning of the 1990s. These precipitation anomalies confirm the occurrence of climate change in the study area and the creation of tension in water resources. The graphs indicate that in the period (1993-2023) there were 14 years of drought conditions, 10 years of wet conditions and 5 years of normal precipitation conditions. In other words, the probability of normal and less conditions occurring is 65.5% and the probability of normal and more precipitation occurring in each year is 34.5%.

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