نوع مقاله : مقاله پژوهشی
نویسنده
استادیار، پژوهشکده حفاظت خاک و آبخیزداری، سازمان آموزش، تحقیقات و ترویج کشاورزی، تهران، ایران
چکیده
افزایش گازهای گلخانه‌ای ضمن تاثیر بر روی عناصر آب و هوایی، سامانه‌های متاثر از این متغیرها، نظیر منابع آب، کشاورزی، محیط زیست، بهداشت و اقتصاد را نیز دگرگون می‌سازد. تغییر آب و هوا، با ایجاد تغییرات در چرخه هیدرولوژی باعث اثرات معنیداری در منابع آب می‌شود. برای بررسی تغییرات آب و هوا در آینده، روش‌های مختلفی وجود دارد که مهمترین آن‌ها مدل‌های اقلیمی هستند. مدل‌های گردش کلی جفت شده (AOGCM) متغیرهای اقلیمی را در وسعت چند ده هزار کیلومتر مربع شبیه‌سازی می‌کنند، اما قادر به شبیه‌سازی فرایندهای منطقه‌ای و کوچک مقیاس آب و هوا نیستند. برای رسیدن به این مهم، از روش‌های ریزمقیاس‌نمایی استفاده می‌شود که یکی از مهمترین آن‌ها روش‌های دینامیکی می‌باشد. این روش، مبتنی بر بالا بردن قدرت تفکیک و تجزیه هرچه بیشتر مدل‌های گردش کلی هستند. در این مطالعه، به بررسی اثرات تغییر آب و هوا بر جریان کمینه حوضه کرخه، به‌عنوان یکی از مهمترین حوضه‌های کشور از لحاظ آورد آبی و کشاورزی، پرداخته شده است. برای این منظور، از مدل ریزمقیاس‌نمایی دینامیکی PRECIS برای برآورد بارش و دما در دوره 2070 تا 2100 و تحت دو سناریوی A2 و B2 استفاده شده است. برای برآورد دبی روزانه در سال‌های آتی نیز از مدل هیدرولوژیکی SWAT (که یک مدل جامع و پیوسته در مقیاس حوضه‌ای می‌باشد) استفاده شده است. بدین صورت که مقادیر بارش و دمای خروجی مدل PRECIS تحت سناریوهای مختلف به مدل وارد و مقدار دبی روزانه برای زیرحوضهها برآورد شد. سپس، شاخص‌های جریان کمینه (سه شاخص Q75 ،Q90 و Q95) از منحنیهای تداوم و سری جریان‌های کمینه 10 و 30 روزه در هر یک از زیرحوضهها محاسبه شد. بررسی شاخص‌های جریان کمینه طی دوره آینده نشان میدهد که تحت سناریوی A2، جریان کمینه حدود 70 درصد افزایش خواهد داشت و این افزایش دبی کمینه در قسمت‌های شمالی حوضه بیشتر است. این در حالی است که تحت سناریوی B2، شاخص‌ها نشان از کاهش 50 درصدی جریان کمینه در افق 2080 دارند. اما توزیع مکانی جریان کمینه نسبت به دوره پایه تغییری نخواهد داشت. لذا، مناطق مرکزی و تا حدودی شمالی حوضه تحت این سناریو، خشکسالی‌های شدیدی را تجربه خواهد کرد. از این‌رو، با توجه به اثرات متفاوت تغییر اقلیم بر جریان کمینه تحت سناریوهای مختلف، در طرح‌های مدیریتی باید عدم قطعیت سناریوها و همچنین، وضعیت اقتصادی و اجتماعی منطقه در آینده مد نظر قرار گیرد.
کلیدواژه‌ها
عنوان مقاله [English]
Assessment of climate change impacts on low flows in Karkheh River Basin in 2070 to 2100
نویسنده [English]
- Sima Rahimi Bondarabadi
Assistant professor of soil conservation and watershed management institute
چکیده [English]
Increasing the greenhouse gases not only has impacts on the weather parameters, but also, has impact on water resources, agriculture, environment, health and economy. Climate change has significant effects on water resources by changing the hydrological cycle. There are several simulation methods for investigating the effects of climate change on different systems in the future, like climate models. The AOGCM model is able to simulate global climate in an area of some ten dousant km2, but, while they are not suitable for regional scale. For this reason, downscaling methods such as dynamic methods are used. These methods are based on high resolution and analysis of climate models. In this research, the impact of climate change was investigated on the low flow of Karkheh Basin as one the most important basins due to its water product and agricultural point of view. For this purpose, the PRECIS which is exponential dynamics and downscaling model, was used to estimate the temperature and precipitation in the period of 2070 to 2100 under A2 and B2 scenarios. The SWAT model, a comprehensive and continuous hydrological model was also used to estimate the flow discharge for the watershed. After calibration and validation of the SWAT model, the amount of rainfall and temperature used as input for PRECIS model under different climate scenarios and finally the daily flow rate was estimated for sub-basins. Then the indices of low flow rates (Q75, Q90 and Q95) and low flow series frequency analysis of 10 and 30 days were assessed. Results showed that rainfall and flow rate have negative and temperature have positive trend. In general, the results of PRECIS model indicated that this model has a good estimate of temperature and precipitation in the region, but, it is not strong for rainfall in autumn and spring, due to the local nature of the precipitation. The climate change assessment under scenario A2, indicated the rise of low flow rate by 70 percent, and this increase of low flow was more in the northern parts of basin, while under the scenario B2 the low flow rate droped by 50 percent for the period of 2080. But, low flow distribution had no change compared to base period.Thus, sever droughts would happen in the central and some northern parts of basin. It can be concluded that under different scenarios, climate change has different impact on the low flow rate. Therefore, due to the different impacts of climate change on low flow rate under different scenarios, uncertainties of scenarios as well as regional economic and social status should be considered in the management plans.
کلیدواژه‌ها [English]
- AOGCM model
- Climate change
- Climate scenarios
- Downscaling
- PRECIS model
- Abbaspour, K.C., M. Faramarzi, S. Seyed Ghasemi and H. Yang. 2009. Assessing the impact of climate change on water resources in Iran. Water Resources Research, W10434, doi:10.1029/ 2008WR007615.
- Abrishamchi, A. and F. Hosseini. 2009. The effects of climate change on temperature and precipitation in the Karkhe River Basin. 8th National Congress on Civil Engineering, Shiraz, Iran (in Persian).
- Arnold, J.G., R. Srinivasan, R.S. Muttiah and J.R. Williams. 1998. Large-area hydrologic modeling and assessment: part I. model development. Journal of the American Water Resources Association, 34(1): 73-89.
- Boyer, C., D. Chaumont, I. Chartier and A.G. Roy. Impact of climate change on the hydrology of St. Lawrence tributaries. Journal of Hydrology, 384: 65-83.
- Cox, P.M., R.A. Betts, C.B. Bunton, R.L.H. Essery, P.R. Rowntree and J. Smith. 1999. The impact of new land surface physics on the GCM simulation of climate and climate sensitivity. Climate Dynamic, 15(3): 183-203.
- Durrans, S.R. and S. Tomic. 2001. Comparison of parametric tail estimators for low-flow frequency analysis. Journal of the American Water Resources Association, 37(5): 1203-1214.
- Georgi, F. and B. Hewitson. 2001. Regional climate information–evaluation and projections. In Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 256 pages.
- Giorgi, F. 1990. On the simulation of regional climate using a limited area model nested in a general circulation model. Journal Climatol, 3: 941–963
- Giorgi, F. and L.O. Mearns. 1999. Introduction to special section: regional climate modeling revisited. Journal of Geophysical Research, 104(D6): 6335–6352
- Ghafouri Rozbehani, A., M. Hosseini, M.R. Tabatabaii, A. Sarreshtehdari and A. Khalkhali. 2013. Simulation of impacts of climate change impacts on water yield of Karkhe River Basin. Final Report of Soil Conservation and Watershed Management Research Institute, 123 pages (in Persian).
- Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, PJ. van der Linden and D. Xioaosu. 2001. Climate change 2001: the scientific basis, contribution of working group I to the third assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 156 pages.
- 2007a. The science of climate change, contribution of working group I to the 2nd assessment report of Intergovernmental Panel on Climate Change. Cambridge University Press, 256 pages.
- 2007b. Technical summary in climate change: impacts, adaptations and climate change. Cambridge University Press, 572 pages.
- Jones, R.G., M. Noguer, D.C. Hassell, D. Hudson, S.S. Wilson, G.J. Jenkins and J.F.B. Mitchell. 2004. Generating high resolution climate change change scenarios using PRECIS. Met Office Hadley Centre, Exeter, UK.
- Mourer, E.P., J.C. Adam and A.W. Wood. 2008. Climate model based consensus on the hydrologic impacts of climate change to the Rio Lempa Basin of Central America. Hydrology and Earth System Sciences Discussions, 5: 3099-3128
- Neitsch, S.L., J.G. Arnold, J.R. Kiniry and J.R. Williams. Soil and water assessment tool, theoretical documentation, version 2009. College Station: Texas Water Research Institute, Technical Report, 406 pages.
- Pyrce, R. 2004. Hydrological low flow indices and their uses. Watershed Science Center, Report No. 4, 33 pages.
- Rahimi Bondarabadi, S., S. Jahanbakhsh Asl and B. Sari Saraf. 2016. Evaluation of a dynamical downscaling climate model for assessment of climate change in Karkheh Basin. Watershed Engineering and Management, 11(3): 633-649 (in Persian).
- Rahimi Bondarabadi, S., S. Jahanbakhsh Asl and B. Sari Saraf. 2016. Study of climate change in Karkha River Basin by dynamical downscaling. Watershed Engineering and Management, (in Press).
- Rifai, H.S., S.M. Brock, K.B. Ensor and P.B. Bedient. 2000. Determination of lowflow characteristics for Texas streams. Journal of Water Resources Planning and Management, 126(5): 310-319.
- Ringius, L., T.E. Downing, M. Hulme and R. Selrod. 1996. Climate change in Africa: issues and regional strategy. University of Oslo, 154 pages.
- Simmons, A.J. and D.M. Burridge. 1981. An energy and angular-momentum conserving vertical finite difference scheme and hybrid vertical coordinates. Monthly Weather Review, 109: 758–766.
- Wang, B., I.S. Kang and J.Y. Li. 2004. Ensemble simulation of Asian-Australian monsoon variability by 11 AGCMs. Journal of Climate, 17: 803–818.
- Wilby, R.L. and I. Harris. 2006. A framework for assessing uncertainties in climate change impacts: low-flow scenarios for the River Thames, UK. Water Resources Research, 42(2): 12-25.
- Yilmaz, K.K., H.V. Gupta and T. Wagener 2008. A process-based diagnostic approach to model evaluation: application to the NWS distributed hydrologic model. Water Resources Research, 44(9): 15-29.
- Zohrabi, N., A. Massah Bavani, A. Telvari and H. Sedghi. 2009. Determining the temporal trend in annual maximum flood series in the Large Karoun River (Iran). 4th Regional Conference on Climate Change, Tehran (in Persian).
)