آسيب پذيري و سازگاري منابع آب با تغيير اقليم (مطالعه موردي حوضه آبخيز چم انجير)

Water stress and access restrictions to water resources are among the most important challenges in the world. It seems that this challenge has intensified under the influence of climate change and has also affected the economy. The aim of this study is to investigate strategies for adapting water resources to climate change. The study area, the Cham Anjir basin located in the southeast of the Karkheh watershed, was selected. To eva‎luate the climate vulnerability index, registered data from the Meteorological Organization and the Ministry of Energy were used, which include variables such as air temperature, precipitation, daily discharge and water table data, and water resource quality data from 1991 to 2021. Additionally, data from the Statistical Center of Iran, including information on the number of wells and their extraction rates, agricultural census, costs, and revenues during the statistical period of 1991-2021, a researcher-constructed questionnaire, and the output of the LARSWG 7 converter based on the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (CMIP6) for the periods 2021-2040 and 2040-2060 using the ACCESS-ESM1-5 model, have been utilized. This research has been conducted using geostatistical techniques, principal component analysis, and ANOVA (analysis of variance). First, the changes in climatic elements over the past decades were examined and revealed, and then the economic-social sensitivity of the stakeholders to these changes was assessed. The degree of climate vulnerability and adaptation to climate change has been examined using the CVI, ASI, and PCI indices. To predict climatic elements, the Lars downscaling converter was used, and for modeling hydrological elements, the parametric regression test and machine learning algorithms (support vector machine algorithm and regression and decision tree algorithm) were employed, and the accuracy of the models was validated. The findings indicated that the risk of climate change on a national and local scale occurred in the years 1991-2021. The frequency of drought events on a national scale has been 41.9%, and wet events 35.5%, and an increase in temperature has occurred, and on a local scale, long-term droughts have increased, and annual rainfall has decreased; the temperature has risen by more than 1.4 ̊ C, and a significant trend has been confirmed. Sensitivity analysis of the Cham Anjir indicated that the annual discharge has decreased by about 23%, the groundwater level by about 17 meters, and the yield of rainfed wheat and barley by about 51%. Sensitivity analysis of the Cham Anjir watershed indicated that the annual discharge has decreased by about 23%, the groundwater level by about 17 meters, and the yield of rainfed wheat and barley by about 51% and its climate vulnerability index score is ranked 30th. The findings indicated that strategies based on the adaptation of water resources to climate change are an appropriate approach to increasing resilience. However, in the context of increasing productivity, there is a significant difference in the strategy of adaptation between the local government and local stakeholders, and the resilience of water resources against climate change is enhanced by resolving the differences in perspectives between these two groups. The findings indicated that during the years 2021-2060, in optimistic, realistic, and pessimistic scenarios, the temperature will increase. The amount of precipitation will decrease in the optimistic scenario, while it will increase in the realistic and pessimistic scenarios. In all three scenarios, the discharge and static water level will decrease.

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