بررسي متغيرهاي موثر بر حجم مخروط هاي واريزه اي مسير دره هراز

Study of variables affecting the volume of the debris cones of the Haraz valley

مخروط واريزه‌اي از مهم‌ترين اشكال دامنه‌اي بوده كه در جابجايي مواد سهم بسزايي دارند. محدوده موردمطالعه بخشي از واحد البرز مركزي در امتداد رودخانه و محور كوهستاني هراز مي‌باشد. هدف از اين پژوهش، اندازه‌گيري متغيرهاي موثر بر هندسه مخروط واريزه‌اي و تعيين نوع ارتباط بين حجم واريزه و متغيرهاي مستقل دخيل بر هندسه مخروط‌هاي واريزه‌اي مي‌باشد. براي دستيابي به اين هدف، 21 مخروط واريزه‌اي به‌طور تصادفي در دامنه‌هاي مشرف در مسير جاده هراز نمونه‌برداري شدند. ويژگي‌هاي مورفومتري اجزاي اصلي مخروط‌هاي واريزه‌اي در مخروط‌هاي منتخب، با استفاده از ابزار مساحي زميني به همراه ثبت موقعيت مكاني و ارتفاع آن‌ها توسط دستگاه GPSاندازه‌گيري شده است. نتايج تحقيق دلالت بر همبستگي در سطح 99 درصد معناداري، بين حجم واريزه به‌عنوان متغير وابسته و متغيرهاي طول معبر و شيب متوسط دارد. همچنين متغيرهاي شيب متوسط، عمق معبر و ليتولوژي در رگرسيون گام‌به‌گام، 94 درصد تغييرات حجم واريزه را به خود اختصاص داده‌اند. درنهايت با انجام تحليل مسير متغيرها مشخص شد كه با كاهش يا افزايش برخي متغيرها و تغيير در ميزان اثرگذاري مستقيم و غيرمستقيم ساير متغيرها، مي‌توان مخاطرات ناشي از مخروط‌هاي واريزه‌اي را كنترل نمود.

Introduction The study area is part of centeralAlborz unit alonge of river and road of Haraz.In this study, debris cone were studied. Cones of debris are in 53°15 to 52° 18 E and 35°53 to 36°07 N in the southwest of Amol.The total area of 21 cones of debris is a equivalent 1/272 KM2.Mount of Damavand is located in the West of mentioned Geomorphologic features. A significant number of are in parts of West and East cones debris. These are used by residents and tourists. Methodology The aim of this study was to evaluate the volume of the debris cones and its relationship with the independent variables. In this study are used weather data of Amol and Rineh stations as well as geological maps in scale 1/100000. After the georeferencing of geological maps,in the ArcGIS software was created2000 m buffer on both sides of theHaraz river and investigated Characteristics of formations on both sides of the river bed. In the next stage of land surveys and field observations, were identified 21 cone debris in the eastern and western slopes of the Haraz river valley.The selected cones of debris islocated in the vicinity of the Haraz river and road. In this research were study the volume of debris as the dependent variable and length ofdebris, top width, middlewidth, the width of the base, height of top and base, average slope and length of the passage as the independent variables.The following data were analyzed in PATH, SPSS and Excel software and results have been evaluated. Results and Discussion Location of the debris cone is upstream domain in the rocky outcrops and steep slopes. type of precipitation from rain to snow is variable and frosty day in the region is high and great. In these circumstances, the physical destruction of rocks are available.Mainly deposits isformed of shale, sandstone, siltstone, quartzite, coal veins and alluvial deposits. In this area shale, sandstone, siltstone ismore than old alluvium, limestone with marl, sandstone andchert. Next, the correlation between the variables under study were examined to assess relationships between variables. The results of the correlation shows that betweenvolume of debris as the dependent variable and variables of average slope and length of the passage is a significant 99 percent.To remove low impact and non-impact variables, stepwise regression model was used.Finally, average slope, depth of passage and lithology as influential factors entered the regressionmodel. The results are explained94 percent of the debris volume changes. The results of path analysis showed that average slope with 0.818 and depth of passage with 0.702 have the most direct and positive effect on the volume of debris. Conclusion Number of 21debris cone were measured at a height of between 1750- 750along theHarazriver androad.in cones are seen on the slopes of the 42-66percent and more in Western range.This shows the temperature variations and climatic characteristics of the region. the average 121 frosty day during 7 month of the year in the station Rineh,the conditions provides for the Physical weathering. The results shows that here is a high correlationbetween the debris volume andlength of the passage and average slope. this research is consistent findings Clawes1991,Harris etal.1993and ildermi 2011 about investigate the causes ofthe formation of a debris flow with emphasis on the role of the slope. Path analysis in this study, we show that average slopeand depth of passage are most direct and positive effect on the volume of debris. Path analysis can helpus to control the risk of increasing the volume of debrisand to be present appropriate solutions to reduce the risk of the volume of the debris.