بررسي اثر تغيير اقليم بر فراواني سيلاب در حوزه آبخيز بازيافت

چكيده انگليسي :

137Assessment of Climate Change Impact on Flood Frequency in Bazoft Watershed Parisa Almasi P almasi@na iut ac ir 2014 Date of Submission September 21 Department of Natural Resources Isfahan university of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr Saeed Soltani Email Ssoltani@cc iut ac irAbstractSince industrial revolution in 19th century humans lifestyle has changed a lot Industrialgrowth deforestation and destruction of the environment increased the greenhouse gases inrecent decades Increase the concentration of greenhouse gases lead to rise in temperatureof the earth s atmosphere globally which called global warming These effects not onlychange the temperature of the atmosphere but also have influence on other climaticparameters which called climate change Studies show that average temperature of theearth s surface has increased by 0 6 C in 20th century Additionally snows cover that formwater resource in many sub basins all around the world has reduced by 10 in recentdecades These changes also affect the extreme climatic events such as flood and drought IPCC reported the increase in floods frequency and droughts especially in Africa and Asia Since increase in probability of floods and droughts can have adverse effects for humanslife study and assessing the effects of climate change on these phenomena is important Inthis study the effects of climate change on flood frequency in bazoft watershed have beenassessed To gain this goal firstly the hydrologic distributed model WetSpa was used tosimulate runoff in this watershed Nash Sutcliffe criterion values were obtained forcalibration and validation of WetSpa model These values were found about 0 63 forcalibration and 0 65 for validation period that showed good efficiency of model for runoffsimulation Then climate change impact on rainfall and temperature as effective variableson flood occurring was assessed In this study one of the General Circulation Model namedHadCM3 with A2 And B2 emission scenarios were used To downscale outputs of GCM statistical downscaling model SDSM version 4 2 was utilized Moreover runoffsimulation was done by downscaled data for 2020 2049 period as near future and 2070 2099 as far future Afterward flood frequency analysis was done for instantaneousmaximum discharge in past and future periods Downscaling results showed increasingtrend in temperature and decreasing trend in rainfall maximum rise in temperature were4 67 and 3 47 C in shahrekord and marghak stations respectively which happen in farfuture under A2 scenario In addition maximum reduction of rainfall in shahrekord andmarghak stations were about 32 9 and 25 2 that expect to happen in far future underA2 scenario Runoff simulation for future periods indicates rise during summer andreduction during spring autumn and winter flood frequency analysis results show that thePearson III is the best distribution to be fitted to instantaneous maximum discharge On thewhole Results showed peaks discharge increase for higher than 10 years return periods Key Words Climate change WetSpa model SDSM Flood frequency analysis Bazoftwatershed

الماسي، پريسا

بررسي اثر تغيير اقليم بر فراواني سيلاب در حوزه آبخيز بازيافت

SDSM , تحليل فراواني سيل , مدل WetSpa