تاثير تغيير اقليم بر خصوصيات بارندگي دوره آينده (مطالعه موردي: استان گلستان)

Development of a hybrid model made of artificial neural network and sediment rating curve for estimating bed load sediment (Case study: Ghotorchay river)

امروزه تغيير اقليم نه فقط در سطوح مديريتي مرتبط با منابع آب بلكه در زندگي روزمره انسان‌ها نيز تاثير آشكاري دارد. بررسي تغييرات متغيرهاي كليدي بارش و دما با در ‌نظر گرفتن اثرات تغيير اقليم در سال‌هاي آينده مي‌تواند در حل معضلاتي چون خشكسالي، سيلاب‌هاي ناگهاني و غيره راه‌گشا باشد. در اين بررسي از داده‌هاي خروجي بانك اطلاعاتي واحد پژوهش‌هاي اقليمي(CRU)، تحت چهار سناريوي انتشار A1، A2،B1 و B2 استفاده شده است. اين داده‌ها براي پارامتر بارش در دو ايستگاه علي‌آباد كتول و مزرعه نمونه ارتش، به ‌عنوان دو ايستگاه مرطوب و نيمه‌خشك استان گلستان، با روش تناسبي كوچك‌مقياس شدند و سپس با روش زمين‌آمار IDW(8)، درون‌يابي شدند و در نهايت سري زماني سناريوي اقليمي در آينده با روش عامل تغيير محاسبه شد. نتايج حاصله از آن در دوره پايه 2010-1981 و دوره آينده 2040-2011 ارزيابي شده است. نتايج مقايسه ميانگين بارش سالانه، نشان از افزايش بارش در ايستگاه علي‌آباد كتول و مزرعه نمونه ارتش به‌ ترتيب حدود 6/7 و 73/8 درصد است. همچنين انتظار مي‌رود در دوره آينده، تعداد رخداد بارش‌هاي حدي افزايش يافته و بيشترين ميزان اين افزايش در ايستگاه‌هاي علي‌آباد و مزرعه نمونه به‌ ترتيب در ماه نوامبر و ژانويه رخ دهد.

Today, climate change has effect not only on the management levels of water resources, but also has some implications in everyday life. Study of changing in key variables of temperature and precipitation with regard to the effects of climate change in coming years can be helpful for solving some problems such as drought and sudden floods. Since others researchers have performed their analysis more than one stationary and just had to show changes in quantity, in this study, we try to consider it by location (region). As well as increasing the number of models and downscaling techniques and the future simulation of periods due to increased uncertainty in the results of climate change, in this study, only a regional model and a downscaling method were used. The purpose of this study is to investigate the effect of climate change on precipitation changes and extreme rainfall events in the next period (2040-2011) in two selected stations in Golestan province. In this study, the data obtained from the database of the Climate Research Unit (CRU), under four emission scenarios A1, A2, B1 and B2 were used. The HADCM3 regional model was used as boundary conditions. This model was released in the fourth assessment report (2007) and widely used for studies around the world. Precipitation data of two weather stations, including Ali Abad Katoul and Mazrae Nemooneh Artesh, as representative of both humid and semi- arid stations in Golestan province, were downscaled by proportional method. Then precipitation data were interpolated using IDW (8) as a statistical method, and finally the time series scenarios of future climate change were calculated by the change factor method. To investigate the number of occurrences of heavy rainfall, the precipitation index greater than 50 mm was considered and for specifying high-risk months in each station, the incidence of extreme rainfall was predicted. The results show that precipitation changes for both stations in autumn, early spring, winter and late and mid-summer increases. The maximum rainfall in November and January are expected that warns the increased intensity of floods at the beginning of winter. At Aliabad Katoul station with a humid climate, precipitation changes for A1 scenario will occur with more intensity and also more precipitation during autumn and early winter and late summer would be expected. In the most of considered scenarios, increase in seasonal rainfall in the regions is expected in all seasons. The largest increase in precipitation in both stations occurred under the B2 scenario. The number of extreme events is expected will be increased in future periods, as this increase in precipitation of the Ali Abad Katoul station will be happening in late summer and early fall, but in Mazrae Nemooneh Artesh station will be