بررسي اثرات تغيير اقليم و كاربري اراضي بر رواناب حوضه نهر اعظم شيراز

The present research investigated the relationship between lan‎d-use an‎d climate changes an‎d their impact on runoff in the Nahre Azam-Shiraz Basin using the SWAT model for the periods of 2004–2020, 2020–2040, an‎d 2040–2060. Runoff from this 94,463-hectare watershed flows through the dry river of Shiraz metropolis; consequently, predicting future monthly runoff variations is crucial for safeguarding citizens an‎d urban infrastructure. The SWAT model was employed to simulate the watershedʹs hydrological regime, while the SUFI-2 algorithm within the SWAT-CUP software was used to optimize model parameters. Daily climatic data were obtained from four meteorological stations (synoptic an‎d rain-gauge) in Shiraz-namely Shiraz, Sarab, Markazi, an‎d Qalat-covering the years 2003 to 2020. Lan‎dsat satellite imagery from 2003 an‎d 2020 was used to generate lan‎d-use maps; following preprocessing an‎d classification, the lan‎d was categorized into six primary lan‎d-use classes. A lan‎d use map for 2040 was prepared using the Markov-Chain method, an‎d the model subsequently assessed the impact of lan‎d use changes occurring between 2003 an‎d 2040 on simulated runoff. To predict the impact of climate change on runoff for the 2040–2060 period, simulations were conducted using the SDSM under three scenarios: RCP2.6, RCP4.5, an‎d RCP8.5. The results indicated that, assuming constant climate data, the average annual surface runoff in the Nahre-Azam basin in 2040-driven by lan‎d use changes would be 6.29% higher than in 2020. The greatest increase an‎d decrease in runoff were projected for autumn(23%) an‎d summer(8.6%), respectively. Furthermore, regarding the impact of future climate change(2040–2060), runoff increases were predicted for all months except December an‎d January under the RCP2.6 scenario, except December under the RCP4.5 scenario, an‎d for all months under the RCP8.5 scenario. The combined effects of future climate change an‎d lan‎d use change(2040–2060) resulted in projected runoff increases across all months an‎d scenarios; compared to the baseline period, increases of 28.4%, 34.8%, an‎d 44.6% were predicted for the RCP2.6, RCP4.5, an‎d RCP8.5 scenarios, respectively. Based on daily temperature data from the Shiraz synoptic station, projections under all three scenarios indicated a rise in monthly minimum temperatures(except in February an‎d March) an‎d monthly maximum temperatures(in all months).

سعيد سلطاني كوپائي , رضا مدرس

مسعود سميعي

رضا جعفري , سعيد اسلاميان , مرتضي خداقلي