تعيين شاخص‌‌هاي فيزيكي و ژئومورفولوژيكي مؤثر بر رخداد انواع جريان‌هاي‌‌ سيلابي در حوزه آبخيز سد كرج

Determination of effective physical and geomorphological indices affecting on occurrence of various types of flood flows in Karaj Dam Watershed

ﺷﻨﺎﺳﺎﯾﯽ ﻓﺮاﯾﻨﺪﻫﺎي ﻫﯿﺪروژﺋﻮﻣﻮرﻓﯿﮏ ﻧﻈﯿﺮ ﺳﯿﻼب ﻋﺎدي )normal flood(، ﺳﯿﻼب وارﯾﺰه اي )debris flood( و ﺟﺮﯾﺎن وارﯾﺰه اي debris flow)( ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ رژﯾﻢ رﺳﻮﺑﯽ و ﺧﻄﺮات و ﺧﺴﺎرات ﻣﺨﺘﻠﻒ ﺑﺴﯿﺎر ﺿﺮوري ﻣﯽ ﺑﺎﺷﺪ. در ﺳﺎل ﻫﺎي اﺧﯿﺮ ﮐﻤﺒﻮد اﻃﻼﻋﺎت ﻣﯿﺪاﻧﯽ ﻣﻮﺟﺒﺎت ﻧﯿﺎز ﺑﻪ اﺳﺘﻔﺎده از ﻣﺪل ﻫﺎي ﻣﺒﺘﻨﯽ ﺑﺮ اﻃﻼﻋﺎت ﭘﺎﯾﻪ ﺣﻮزه آﺑﺨﯿﺰ را ﻓﺮاﻫﻢ ﮐﺮده اﺳﺖ. ﻫﺪف از اﯾﻦ ﻣﻄﺎﻟﻌﻪ، ﺗﻮﺳﻌﻪ روش ﮐﺎرﺑﺮدي ﺑﺮاي ﭘﯿﺶ ﺑﯿﻨﯽ رﺧﺪاد اﻧﻮاع ﺟﺮﯾﺎن ﺳﯿﻼﺑﯽ ﺑﺎ اﺳﺘﻔﺎده از وﯾﮋﮔﯽ ﻫﺎي ﻓﯿﺰﯾﮑﯽ ژﺋﻮﻣﻮرﻓﻮﻣﺘﺮي( و ژﺋﻮﻣﻮرﻓﻮﻟﻮژﯾﮑﯽ ﺣﻮﺿﻪ ﻣﯽ ﺑﺎﺷﺪ. اﯾﻦ ﭘﮋوﻫﺶ، ﺑﺎ اﺳﺘﻔﺎده از روش ﺗﻮﺻﯿﻔﯽ-ﺗﺤﻠﯿﻠﯽ و اﺑﺰارﻫﺎﯾﯽ ﻣﺎﻧﻨﺪ ﻋﮑﺲ ﻫﺎي ﻫﻮاﯾﯽ، ﺗﺼﺎوﯾﺮ ﻣﺎﻫﻮاره اي، ﻧﻘﺸﻪ ﻫﺎي ﺗﻮﭘﻮﮔﺮاﻓﯽ و ﺳﺎﻣﺎﻧﻪ GIS اﻧﺠﺎم ﺷﺪ. در روش ﺗﻮﺻﯿﻔﯽ، ارزﯾﺎﺑﯽ ﻣﯿﺪاﻧﯽ رﺳﻮﺑﺎت اﻧﻮاع ﺟﺮﯾﺎن ﻫﺎي ﺳﯿﻼﺑﯽ 28 ﺗﯿﺮﻣﺎه ﺳﺎل 1394 در 70 زﯾﺮﺣﻮزه آﺑﺨﯿﺰ ﺳﺪ ﮐﺮج اﻧﺠﺎم ﺷﺪ. از 70 زﯾﺮﺣﻮﺿﻪ ﻣﻄﺎﻟﻌﺎﺗﯽ، 30 زﯾﺮﺣﻮﺿﻪ ﺟﺮﯾﺎن وارﯾﺰه اي، 16 زﯾﺮﺣﻮﺿﻪ ﺳﯿﻼب وارﯾﺰه اي و 24 زﯾﺮﺣﻮﺿﻪ ﺑﺎ ﺳﯿﻼب ﻋﺎدي ﻣﻮاﺟﻪ ﺷﺪﻧﺪ. در روش ﺗﺤﻠﯿﻠﯽ، در ﻫﺮ زﯾﺮﺣﻮﺿﻪ، 32 ﻋﺎﻣﻞ ژﺋﻮﻣﻮرﻓﻮﻣﺘﺮي از ﻣﺪل رﻗﻮﻣﯽ ارﺗﻔﺎﻋﯽ )DEM( ﺑﺎ دﻗﺖ ﻣﮑﺎﻧﯽ 25 ﻣﺘﺮ و ﭘﻨﺞ ﭘﺎراﻣﺘﺮ ژﺋﻮﻣﻮرﻓﻮﻟﻮژﯾﮑﯽ از ﻧﻘﺸﻪ رﺧﺴﺎره ﻫﺎي ﻓﺮﺳﺎﯾﺶ ﺗﻮده اي، اﺳﺘﺨﺮاج و ﺑﻪﻣﻨﻈﻮر ﺗﻌﯿﯿﻦ ارﺗﺒﺎط ﺑﺎ ﻧﻮع ﺟﺮﯾﺎن ﻫﺎي ﺳﯿﻼﺑﯽ ﻣﺸﺎﻫﺪاﺗﯽ ﺑﻪ ﺑﺮﻧﺎﻣﻪ آﻣﺎري SPSS ﻣﻨﺘﻘﻞ ﺷﺪ. ﻧﺘﺎﯾﺞ ﺗﺤﻠﯿﻞ وارﯾﺎﻧﺲ ﯾﮏ ﻣﺮﺣﻠﻪ اي )ANOVA( و ﻣﻘﺎﯾﺴﻪ ﭼﻨﺪﮔﺎﻧﻪ ﺑﻮﻧﻔﺮوﻧﯽ )multiple comparisons Bonferroni( ﻧﺸﺎن داد، ﭼﻬﺎر ﻋﺎﻣﻞ ﻣﻮرﻓﻮﻣﺘﺮي ﻃﻮل آﺑﺮاﻫﻪ اﺻﻠﯽ )Lm(، ﻣﺤﯿﻂ ﺣﻮﺿﻪ )p(، ﻃﻮل ﺣﻮﺿﻪ )Lb( و ﻣﯿﺎﻧﮕﯿﻦ ﻋﺮض ﺣﻮﺿﻪ )(Wb در ﺗﻔﮑﯿﮏ اﻧﻮاع ﺟﺮﯾﺎن ﺳﯿﻼﺑﯽ ﻣﺆﺛﺮ ﺷﻨﺎﺳﺎﯾﯽ ﺷﺪﻧﺪ. ﺑﻪ ﻣﻨﻈﻮر اﻧﺘﺨﺎب دو ﭘﺎراﻣﺘﺮ ﮐﻠﯿﺪي ﻣﻨﺎﺳﺐ ﺗﺮ و ﻣﻘﺎدﯾﺮ آﺳﺘﺎﻧﻪ آن ﻫﺎ، ﺑﺮرﺳﯽ راﺑﻄﻪ زوﺟﯽِ ﭼﻬﺎر ﻣﺘﻐﯿﺮ در ﺷﺶ ﻧﻤﻮدار )ﮐﺮت( ﭘﺮاﮐﻨﺶ ﺳﻪ ﮔﺎﻧﻪ ﻧﻘﻄﻪ اي ﻧﺸﺎن داد ﻃﻮل آﺑﺮاﻫﻪ اﺻﻠﯽ)(Lm و ﻣﯿﺎﻧﮕﯿﻦ ﻋﺮض ﺣﻮﺿﻪ )(Wb ﻣﻨﺎﺳﺐ ﺗﺮﯾﻦ ﻋﻮاﻣﻞ ﻣﺆﺛﺮ ﺑﺮاي ﭘﯿﺶ ﺑﯿﻨﯽ ﺟﺮﯾﺎن ﻫﺎي ﺳﯿﻼﺑﯽ ﺑﺎ ﮐﻤﯿﻨﻪ ﻣﺠﻤﻮع ﺧﻄﺎﻫﺎي ﻣﻮﺟﻮد در ﻣﺤﺪوده ﻃﺒﻘﺎت ﺗﻔﮑﯿﮑﯽ ﺟﺮﯾﺎن ﻫﺎ ﺑﺮ روي ﻧﻤﻮدارﻫﺎ ﺑﻮدﻧﺪ ﮐﻪ در ﺣﻮﺿﻪ ﻫﺎي ﻃﻮﻻﻧﯽ ﺑﺎ 4>Lm ﮐﯿﻠﻮﻣﺘﺮ ﺳﯿﻼب ﻋﺎدي و در ﺣﻮﺿﻪ ﻫﺎي ﮐﻮﺗﺎه ﺑﺎ 4 Wb ﮐﯿﻠﻮﻣﺘﺮ ﺑﺎﺷﺪ، ﺳﯿﻼب وارﯾﺰهاي و ﭼﻨﺎﻧﭽﻪ 1

Identification of hydrogeomorphic processes such as normal flood, debris flood and debris flow on alluvial fan (at the outlet of the watershed) is essential due to the type of sedimentary regime and various hazards. In recent years, the lack of field information has led to the need to use models based on basic watershed information. The aim of this study is to develop a practical method for predicting the occurrence of various types of flood flow, using physical and geomorphological characteristics of watersheds. In this study, a descriptive-analytical method and some of tools, such as aerial photographs, satellite images, topographic maps were used. First, by descriptive method, field evaluation of sediments of various types of flood currents was carried out on July 19, 2015 in 70 sub-watersheds of in Karaj Dam Watershed. Results showed that out of 70 sub-basins, 30 sub-basins, debris flow, 16 sub-basin debris flood and 24 sub-basins were normal floods. Then, in the analytical method, 32 geomorphometric features of watersheds by 25-meter spatial digital model (DEM) and five geomorphological features of sub-watersheds by mass movement maps were extracted and then were transferred to the SPSS statistical program to determine the relationship with the type of flood flow. The results of ANOVA and Bonferroni multiple comparisons showed that four morphometric factors “main channel length, basin perimeter, mean basin width and basin length” were identified in differentiation of flood flow types. To achieve the two appropriate key parameters and threshold values, four variable pairwise were copaird by pair in six triple scatter plots. The results showed that “The main channel length (Lm) and the mean basin width (Wb)” has the least total errors of the observation streams, were selected as the most appropriate factors for predicting flood flows. In long basins with Lm>4 km, normal flooding occurs, and in short basins with Lm1 km, floods occur, and if Wb