Velocity of debris flow is one of the most important characteristics for the protective construction design. Since debris flows are rare events, and observations are conducted only on stations in Russia, Ukraine, Italy, Switzerland, USA, China, Japan and New Zealand, the velocity is calculated rather than measured. Nowadays, a large number of videos with passing debris flows have appeared on the Internet. Scientists can use such video materials to obtain qualitative and quantitative characteristics of the debris flow. Therefore, the aim of our research is an attempt to measure the debris flow velocity using video materials and compare the obtained results with the calculated values using various methods. The debris flow that came down in Firgen, Austria on August 4, 2012 was chosen as the object of our study. The video was carried out from several angles, so it was possible to select a section of the channel, through which we could measure the debris flows waves velocity. In addition, we calculated the velocities of waves by formulas adopted in the regulatory documents and compared with the measured by video values. During the video analysis, debris flow velocities at different sites were observed: minimum-7.2 m/s and maximum-10 m/s. The calculated values varied from 4.5 m/s to 11.4 m/s. Moreover, we applied model of the transport-shear process of debris flow formation developed by Yu. B. Vinogradov. When we were comparing the obtained debris flow discharges with results from Austrian colleagues, we found out that the values were similar to each other. However, internal scatter in the model changed from 151 to 190 m 3 /s, while in the report of Austrian colleagues the discharges were from 80 to 250 m 3 /s.
<p>Debris flow is one of the most hazardous events that occur in all mountain regions. &#160;Direct debris flow damage includes loss of human life, destruction of houses and facilities, damage to roads, rail lines and pipelines, vehicle accidents, and many other losses that are difficult to quantify. In July 2015, in the valley of the Barsemdara River (Gorno-Badakhshan Autonomous Region, Tajikistan), plenty of debris flows were observed. As a result, residential areas, social facilities, and infrastructure in Barsem village and neighboring settlements were destroyed and flooded. Besides, debris flow deposits blocked the Gunt River with the subsequent formation of a dammed lake with a maximum volume of 4.0 million m<sup>3</sup>.&#160;<br>The aim of this study was to obtain hydrographs of debris flow waves in the source and detailed zoning of the Barsemdara river valley. For the debris flow source, we applied transport-shift model. Equations of this model were developed by Yu.B. Vinogradov basing on Chemolgan experiments of artificial debris flows descending. Previously, the model characteristics were compared with the observational data of the Chemolgan experiments, and the results were found to be satisfactory [Vinogradova, Vinogradov, 2017]. Based on the equations, a computer program was created in the programming language Python. Besides, we improved the model by adding flow velocity calculations, and eventually it became possible to obtain hydrographs. To investigate quantitative characteristics of the debris flow in the river valley we implied a two-dimensional (2D) model called FLO-2D PRO. It is based on the numerical methods for solving the system of Saint-Venant equations. Besides, in this model, it is assumed that debris flows move like a Bingham fluid (viscoplastic fluid) [O'Brien et al., 1993]. The input information for modeling was digital elevation model (DEM) and previously obtained hydrographs. The output information included flow depth, velocity distribution and hazard level of the territory. The results of the study will be reported.</p><p>1. &#160; &#160;Vinogradova T.A., Vinogradov A.Y. The Experimental Debris Flows in the Chemolgan River Basin // Natural Hazards. &#8211; 2017. &#8211; V. 88. &#8211; P. 189-198.<br>2. &#160; &#160;O'Brien J. S., Julien P.Y., Fullerton W.T. Two-dimensional water flood and mudflow simulation //Journal of hydraulic engineering. &#8211; 1993. &#8211; V. 119, No 2. &#8211; P. 244-261.</p>
Construction of debris flow protection structures is impossible without studying the processes first. Therefore, the purpose of this research was to calculate the magnitude of debris flows in three study areas. Initial information was provided by JSC Sevkavgiprovodkhoz and the Research Center "Geodinamika". The first object of this research was the river Ardon and its tributary the Buddon, because of disastrous consequences for Mizur village of passed debris flows and floods. Modeling of unsteady water movement was carried out for estimation of potential flooding. During modeling, 5 cases of flash floods and debris flows of various probabilities from 0.5% to 1% percent were considered. Therefore, maximum floods for the cross-sections above and in the Mizur village itself were obtained. The second study area was the Chat-Bash stream, which is also situated in the north of Caucasus mountains. For this stream, the maximum discharge that could impact the mining complex at Tyrnyauz was determined. The third study area was the Krasnoselskaia river due to frequent floods in Yuzhno-Sakhalinsk. Applying three cases of various probabilities from 10% to 0.1%, the model determined maximum discharge and water level for the last cross-section above confluence into the Susuya river. Numerical experiments for all study areas with different roughness values were conducted to identify optimal ones. Comparing the model results for all study areas with empirical formulas (Golubcov V.V., Herheulidze I.I., Kkhann, Sribnyj and ASFS of EMERCOM of Russia) revealed that formulas contain only average depth slope angle and empirical coefficients and do not allow estimating flood areas and maximum characteristics of the event with a certain degree of accuracy.
Для проектирования сооружений противоселевой защиты необходимо знать значения таких характеристик селя, как скорость потока и давление селевой массы на преграду. Определение этих характеристик часто вызывает трудности изза того, что сель достаточно редкое событие и постоянные наблюдения за ними ведутся на селестоковых станциях, которых во всем мире немного. В настоящее время в интернете появилось большое количество видеосъемок, на которых запечатлен сход селевого потока. Такой материал можно использовать для получения не только качественных, но и количественных характеристик селевого потока. В тех случаях, когда имеется возможность определить на видео масштаб и конкретное место схода селя, определение его скорости и других характеристик составляет выполнимую задачу. В статье представлена попытка количественной оценки скорости селевого потока по материалам видеосъемки с последующим сравнением полученных результатов со значениями, рассчитанными по различным методикам. В качестве объекта нашего исследования был выбран селевой поток, сошедший в Австрии, г. Фирген 4 августа 2012 года. Съемка производилась с нескольких ракурсов, что позволило выбрать участок канала, на котором оказалось возможным произвести измерение скорости движения серии селевых волн. Расчет скорости селевого потока и давления на препятствие производился по методикам разных исследователей. Измеренные на видеоролике скорости селевых волн на разных участках составили: минимальная 7,4м/с, максимальная 10 м/с. Различия между рассчитанными по разным методикам и измеренными по видео значениями составляют от 0,1 м/с до 4,8 м/с. Кроме этого, были проведены расчеты расхода селевого потока и плотности селевой массы. Нами использовалась модель транспортносдвигового селевого процесса, разработанная Ю.Б. Виноградовым. При сравнении полученных значений с результатами австрийских коллег было выявлено, что значения характеристик похожи, но разброс значений по данной модели меньше. Виноградов Ю.Б. Этюды о селе-вых потоках. Л.: Гидрометеоиздат, 1980. 144 с. Голубцов В.В. О гидравлическом сопротивлении и формуле для расчета средней скорости течения горных рек // Труды КазНИГМИ. 1969. Вып. 33. С. 30-41. Гонор А.Л., Пик-Пичак Е.Г. Чис-ленное моделирование удара снежной лавины по твердой стенке // Известия Академии наук СССР. Механика жидкости и га-за. 1983. № 6. С. 86–91. Казаков Н.А. Волновая динамика селей // Геоэкология. Инженерная геология. Гидрогеология. Гео-криология. 2001. № 2. С. 158-164. Молжигитов С.К. Оценка удар-ной нагрузки селевого потока на поперечную жесткую преграду // Международный журнал при-кладных и фундаментальных ис-следований. 2016. № 3 (часть 1). С. 16-20. Срибный М.Ф. Формула средней скорости течения рек и их гид-равлическая классификация по сопротивлению движению // Ис-следования и комплексное ис-пользование водных ресурсов. М.: Изд-во АН СССР, 1960. С. 204-220. Aulitzky Н. The debris flows of Aus-tria // Bulletin of the International Association of Engineering Geology (Bulletin de l'Association Interna-tionale de Géologie de l'Ingénieur). 1989. Volume 40. Issue 1. P. 5–13. DOI: 10.1007/BF02590338 Hübl J. Ereignisdokumentation, Band 3: Jahresrückblick der Ereignisse. IAN Report 150. Wien, Februar 2013, 88 p. Vinogradova T.A., Vinogradov A.Y. The experimental debris flows in the Chemolgan river basin // Natural Hazards. 2017. Vol. 88. Suppl. 1. PP. 189-198. DOI: 10.1007/s11069-017-2853-z For mud dams construction it is necessary to clarify characteristics of debris flow such as flow velocity and pressure on the barrier. Determining these characteristics often causes difficulties due to the fact that debris flow is rather rare event and constant monitoring of them is carried out at mud flow observation station stations, which are few worldwide. Currently large number of videos have appeared on the Internet that captures debris flow descent. This material can be used to obtain not only qualitative, but also quantitative characteristics of the debris flow. In cases, when it is possible to determine the scale and specific location of debris flow on a video, measuring its velocity and other characteristics is a workable task. This research present an attempt to quantify the debris flow velocity based on the video materials with the subsequent comparison of the results obtained using various methods. The object of our study was the debris flow that came down in Austria, in Firgen on August 4, 2012. The survey was carried out from several angles, which made it possible to select a section of the channel to measure the velocity of debris flow wave train. Calculation of flow velocity and pressure on the barrier was conducted by several methods developed by various researchers. Debris flow velocities measured on the video are minimum 7,4m/s, maximum 10 m/s. Differences between calculated by various methods and measured on the video values range from 0,1 m/s to 4,8 m/s. Aulitzky Н. The debris flows of Austria. Bulletin of the International Association of Engineering Geology (Bulle-tin de l'Association Internationale de Géologie de l'Ingé-nieur), 1989, vol. 40, iss. 1, pp. 5-13. DOI: 10.1007/BF02590338 Golubtsov V.V. O gidravlicheskom soprotivlenii i for-mule dlya rascheta srednei skorosti techeniya gornykh rek [About the hydraulic resistance and a formula for calcula-tion of average speed of a current of the mountain rivers]. Trudy Kazakhskogo regional'nogo nauchno-issledovatel'skogo gidrometeorologicheskogo instituta [Transactions of the Kazakh Regional Hydrometeorologi-cal Research Institute], 1969, no. 33, pp. 30-41. (in Russian). Gonor A.L., Pik-Pichak E.G. Chislennoe modelirovanie udara snezhnoi laviny po tverdoi stenke [Numerical mod-eling of snow avalanche impact on a solid wall]. Izvestiya Akademii nauk SSSR. Mekhanika zhidkosti i gaza [News of the USSR Academy of Sciences. Mechanics of fluid and gas], 1983, no. 6, pp. 86–91. (in Russian). Hübl J. Event documentation, Volume 3: Annual review of events. IAN Report 150. Vienna, February 2013, 88 p. (in German). Kazakov N.A. Volnovaya dinamika selei [Wave dynam-ics of debris flows]. Geoekologiya. Inzhenernaya geologi-ya. Gidrogeologiya. Geokriologiya. [Geoecology. Engi-neering geology. Hydrogeology. Geocryology], 2001, no 2, pp. 158-164. (in Russian). Molzhigitov S.K. Otsenka udarnoi nagruzki selevogo potoka na poperechnuyu zhestkuyu pregradu [Estimation of the impact load of the mudflow on the transverse rigid barrier] Mezhdunarodnyi zhurnal prikladnykh i fundamen-tal'nykh issledovanii [International journal of applied and fundamental research], 2016, no. 3 (part 1), pp. 16-20. (in Russian; abstract in English). Sribnyi M.F. Formula srednei skorosti techeniya rek i ikh gidravlicheskaya klassifikatsiya po soprotivleniyu dvizheniyu [Formula of the average flow velocity of riv-ers and their hydraulic classification by resistance to the movement] Issledovaniya i kompleksnoe ispol'zovanie vodnykh resursov [Researches and complex use of water resources]. Moscow: Publishing house of the USSR Academy of Science, 1960, pp. 204-220. (in Russian). Vinogradov Yu.B. Etyudy o selevykh potokakh [Etudes about mud stream]. Leningrad, Gidrometeoizdat Publ., 1980. 144 p. (in Russian). Vinogradova T.A., Vinogradov A.Y., 2017. The experi-mental debris flows in the Chemolgan river basin. Natural Hazards, Vol. 88, No. 1, pp. 189-198. DOI: 10.1007/s11069-017-2853-z
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