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As global warming intensifies, the changes of glacial lakes in Xizang need to be carefully examined. Because of their special geographical location and physical characteristics, it is extremely liable to occur Glacial Lake Outburst Flood, which poses a serious threat to the surrounding residents, infrastructure and ecological environment. However, our knowledge about the specific distribution of glacial lakes across the region and their potential risks is still limited. Therefore, by using GIS spatial analysis and the parametric optimal geodetector method, we analyzed the spatio-temporal changes of glacial lakes in Xizang from 1990 to 2015, and the extent to which the annual total precipitation, annual average temperature, annual relative humidity and glacier area change factors affected the changes of glacial lakes. The statistics and analysis show that from 1990 to 2015, the growth rates of glacial lakes in quantity and area were 2.57% and 6.32%, respectively, while the number and area of moraine lakes increased by 18.96% and 28.45%, respectively. Through the analysis of the optimal parameter geographic detector, it is found that the change of glacier area has the greatest influence on the area and number of glacial lakes, with the q value 0.5006 and 0.1696, respectively. In the interaction detection, the interaction between temperature and glacier area change has the strongest explanatory power to the change of glacial lake area. The interaction of the precipitation and the glacier area change has the strongest explanatory power relative to the change of glacier lake number, and the relationship is non-linear. The change of glacial lake is the result of the interaction of various factors. This paper puts forward the quantitative evaluation of various factors and their interactions by using geographic detectors, and reveals the spatio-temporal distribution rule of glacial lakes in Xizang and its influencing factors. On the one hand, it can provide a scientific basis for the early warning and prevention of outbursts of flood from glacial lakes, and help to reduce disaster losses. On the other hand, this study also provides an important reference for the evolution of glacial lakes in the context of global climate change. [ABSTRACT FROM AUTHOR]

As global warming intensifies, the changes of glacial lakes in Xizang need to be carefully examined. Because of their special geographical location and physical characteristics, it is extremely liable to occur Glacial Lake Outburst Flood, which poses a serious threat to the surrounding residents, infrastructure and ecological environment. However, our knowledge about the specific distribution of glacial lakes across the region and their potential risks is still limited. Therefore, by using GIS spatial analysis and the parametric optimal geodetector method, we analyzed the spatio-temporal changes of glacial lakes in Xizang from 1990 to 2015, and the extent to which the annual total precipitation, annual average temperature, annual relative humidity and glacier area change factors affected the changes of glacial lakes. The statistics and analysis show that from 1990 to 2015, the growth rates of glacial lakes in quantity and area were 2.57% and 6.32%, respectively, while the number and area of moraine lakes increased by 18.96% and 28.45%, respectively. Through the analysis of the optimal parameter geographic detector, it is found that the change of glacier area has the greatest influence on the area and number of glacial lakes, with the q value 0.5006 and 0.1696, respectively. In the interaction detection, the interaction between temperature and glacier area change has the strongest explanatory power to the change of glacial lake area. The interaction of the precipitation and the glacier area change has the strongest explanatory power relative to the change of glacier lake number, and the relationship is non-linear. The change of glacial lake is the result of the interaction of various factors. This paper puts forward the quantitative evaluation of various factors and their interactions by using geographic detectors, and reveals the spatio-temporal distribution rule of glacial lakes in Xizang and its influencing factors. On the one hand, it can provide a scientific basis for the early warning and prevention of outbursts of flood from glacial lakes, and help to reduce disaster losses. On the other hand, this study also provides an important reference for the evolution of glacial lakes in the context of global climate change. [ABSTRACT FROM AUTHOR]

Barrier dams formed by the large-scale debris flow that blocks the river often are subjected to a high risk of break. The catastrophic flood arising from dam break has been confirmed as the most serious hazard-causing body of the debris flow dams. A novel method is proposed in this study to regulate the discharge of the debris flow dam break based on a flexible protective net (FPN). Next, 17 sets of flume experiments were performed to investigate the effects of different inflow discharges, dam grain size distribution, and downstream boundary locations of the FPN on discharge regulating effectiveness, such that the flow regulating mechanism of the FPN was revealed. As indicated by the results, (1) a significant traceability scarp was formed in the debris flow dam-break process. The whole dam-break process fell into three stages, i.e., traceability scarp formation, traceability scarp erosion, and traceability scarp decline. (2) When the downstream boundary of the FPN was located close to the downstream dam toe of the debris flow dam, regardless of the inflow discharge and the grain size distribution of the dam, the FPN laid on the surface of the debris flow dam took on critical effect in regulating the outburst discharge. (3) The inhibitory effect of the FPN on the particle initiation and the interception effect on particle transport, as well as the energy dissipation effect of the FPN and coarsening layer on outburst flood, fundamentally accounted for the good flow regulating effect of the above-described method. The method proposed in this study is capable of achieving an ideal outburst flood regulating effect by ensuring construction safety. [ABSTRACT FROM AUTHOR]

The expansion of potentially hazardous glacial lakes is a symptom of global warming during this interglacial period. A pertinent example is the Jiongpu glacial lake in southeastern Tibet, the area of which has expanded approximately fivefold in the last half-century. However, recently, the glacier tongue has retreated to a high steep slope, and the rate of retreat of the glacier and expansion of the lake have temporarily slowed. The risk of a glacier tongue landslide after glacier detachment and subsequent glacial lake outburst flood (GLOF) needs to be assessed. In this study, we employed a combination of unmanned aerial vehicle (UAV), sonar, geological radar, remote sensing, field investigation, sampling, drilling, and dating techniques to determine the critical parameters of potential GLOFs, including glacier tongue geometry, lake bathymetry, and moraine dam geometry and composition. Utilizing empirical models and multiphase flow models, we identified the most hazardous triggers and simulated the processes of a glacier tongue landslide into the lake, moraine dam overtopping by a displacement wave, and subsequent flood evolution. The results showed that the most hazardous trigger in volume is a glacier tongue landslide, accounting for 58.29 % of all triggers associated with potential GLOFs. Lapped by the largest glacier tongue landslide impulse wave, the moraine dam would not fail because the minimum safety factor is approximately 1.66 ± 0.7 according to empirical methods and geological slope simulation. However, overtopping would occur, resulting in a peak discharge of approximately 9740 ± 4137 m3/s at the moraine dam based on r.avaflow calculations. The flood would reach the densely populated Jinling township and inundate approximately 46 ± 4.55 % of the houses according to HEC-RAS. Reducing the water level of the glacial lake represents an effective strategy for mitigating potential losses. This concise, physics-based method effectively assesses GLOF triggers and processes and can be applied to risk assessments of other expanding glacial lakes. • A glacial lake with abruptly slowing expansion • Quantifying trigger volumes including glacier detachments • Modeling from triggers to GLOFs • Dating historical GLOFs by OSL [ABSTRACT FROM AUTHOR]