Typical Glacial Lake Outburst Flood Evolution Simulation In Tibet

With global warming, glaciers disaster increased year by year and glacier potential harmfulness has attracted great attention and become a hot topic in the world. Glacier lakes are numerous, distributed widely, and higher disaster risk. In recent decades, China’s glacial lake outburst events are endless, mainly in Tibet, glacial lakes disaster frequency becomes higher and the distribution range becomes wider.Huanghu is studied as one of glacial lakes in Nianchu River Basin of Tibet classified as potentially dangerous, has never broken the dam. We understand huanghu topography and climate characteristics, and determine from huanghu to Gyangze County as the study area through field research. We set 10 key sections, and set 3 scenarios according to different degrees outburst. The two-dimensional dam-break flood numerical model is used to simulate every section peak flow and outburst flood evolution. The simulation results showed that:(1) Z1 sectional flow process lines are often steep fall and up dramatically, but the downstream portion of the flow process is a multi-line presented wavy.(2) When we compare the peak flow in the same section we found scenario 1>scenario 2>scenario3.(3) The more closer to the break, a section peak flow is gradually becoming more sensitive to various dam break degrees.(4) Although the length of time of each simulation is not the same in every scenario and the maximum inundation area are not the same, all share a similar trend that all the flooded area will become larger to stable when the average depth tends to minium.Gyantse is the concentration of population residence, so especially need to focus on the peak flow values, scenario 1 is 1095 m3/s, scenario 2 is 409 m3/s, scenario 3 is 734 m3/s. Based on the literature, we know the peak flow of storm flood with recurrence interval of ten thousand years is less than 1000 m3/s. So scenario 1 does much harm to personal and property safety of Gyangz obviously, we must adopt corresponding measures in time in order to reduce losses do their best possible.The significance of this study is not only to provide Nianchu River disaster prevention and mitigation for analytical tools and a theoretical basis, but also conducive to the harmonious development of the ecological environment, economy and society in Tibet.