مدل‌سازي هيدرولوژيكي تجمع و ذوب برف در حوضه‌هاي نيمه‌خشك و كوهستاني (مطالعه موردي: حوضه باراريه)

Hydrological Modeling of Snow Accumulation and Melting in Semi-Arid and Mountainous Watersheds (Case study: Bar Arye Watershed

در اين تحقيق به‌منظور شبيه‌سازي فرآيندهاي تجمع و ذوب برف حوضه باراريه كه حوضه‌اي كوهستاني با ﻣﺘﻮﺳﻂ ارﺗﻔﺎع 2225 ﻣﺘﺮ از ﺳﻄﺢ درﯾﺎ ﻣﯽﺑﺎﺷﺪ از ﻣﺪل WetSpa، اﺳﺘﻔﺎده ﮔﺮدﯾﺪ. اﻃﻼﻋﺎت ورودي ﻣﺪل ﺷﺎﻣﻞ ﺑﺎرش، دﻣﺎي ﻫﻮا، ﺗﺒﺨﯿﺮ و ﺗﻌﺮق ﭘﺘﺎﻧﺴﯿﻞ روزاﻧﻪ، در دوره آﻣﺎري 1382 ﺗﺎ 1387 و ﻧﻘﺸﻪﻫﺎي ﮐﺎرﺑﺮي اراﺿﯽ، ﺑﺎﻓﺖ ﺧﺎك و رﻗﻮم ارﺗﻔﺎﻋﯽ ﻣﯽﺑﺎﺷﺪ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﻌﯿﺎر ارزﯾﺎﺑﯽ ﻧﺎش - ﺳﺎﺗﮑﻠﯿﻒ در دو دوره واﺳﻨﺠﯽ و ارزﯾﺎﺑﯽ ﮐﻪ ﺑﻪﺗﺮﺗﯿﺐ ﺑﺮاﺑﺮ ﺑﺎ 0/67 و 0/69 ﻣﯽﺑﺎﺷﻨﺪ ﻣﺸﺨﺺ ﺷﺪ ﮐﻪ ﻣﺪل ﺑﻪﺧﻮﺑﯽ ﻗﺎدر ﺑﻪ ﺷﺒﯿﻪﺳﺎزي ﺟﺮﯾﺎن رودﺧﺎﻧﻪ ﺑﺎرارﯾﻪ ﻣﯽﺑﺎﺷﺪ. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ ﻣﺸﺨﺺ ﺷﺪ آﺳﺘﺎﻧﻪ ﺷﮑﻞﮔﯿﺮي ﺑﺮف در اﯾﻦ ﺣﻮﺿﻪ درﺟﻪ ﺣﺮارت 0/11 ﺳﻠﺴﯿﻮس ﻣﯽﺑﺎﺷﺪ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﻘﺎدﯾﺮ ﻣﺘﻮﺳﻂ ﻣﺎﻫﺎﻧﻪ ﻣﺆﻟﻔﻪﻫﺎي ﺑﯿﻼن ﻣﺸﺨﺺ ﮔﺮدﯾﺪ ﮐﻪ دو ﻣﺎه دي و ﺑﻬﻤﻦ ﺑﻪﺗﺮﺗﯿﺐ ﺑﺎ 29/25 ﻣﯿﻠﯽﻣﺘﺮ و 37/94 ﻣﯿﻠﯽﻣﺘﺮ ﺑﯿﺶﺗﺮﯾﻦ ﻣﻘﺪار آب ﻣﻌﺎدل ﺑﺮف و دو ﻣﺎه اﺳﻔﻨﺪ و ﻓﺮوردﯾﻦ ﺑﺎ 38/89 ﻣﯿﻠﯽﻣﺘﺮ و 37/14 ﻣﯿﻠﯽﻣﺘﺮ ﺑﯿﺶﺗﺮﯾﻦ ﻣﻘﺪار ذوب ﺑﺮف را دارا ﻣﯽﺑﺎﺷﻨﺪ.

In this study, the WetSpa model was utilized to simulate the snow accumulation and melting processes in the Bar Arye mountainous watershed with an average altitude of 2225 meters above the mean sea level. The input data used in this study included daily records of precipitation, air temperature and potential evapotranspiration, covering the period of 2003 to 2008, as well as three types of maps, namely; land use, soil texture and topography maps. According to Nash-Sutcliffe assessment index values (0.67, 0.69) for the calibration and validation periods, the model could simulate the Bar Arye river flow with high accuracy. The results indicated that the temperature threshold for snow formation in this catchment was 0.11°C. According to the water balance components, it was indicated that the maximum amounts of equivalent snow water belonged to the months of December (29.25 mm) and January (37.94 mm), while the maximum snow melt values were observed during March and April , as 38.89 mm and 37.14 mm, respectively.