Gravel Accumulation in Deposits of Viscous Debris Flows with Hyper-concentration

According to the observational data of viscous debris flows with hyper-concentration, debris flows can be classified into three types:high-viscous, viscous, and sub-viscous debris flows.Distinct formation mechanism of different graded bedding structures in deposits of viscous debris flows was analyzed in this paper by using their yield-stress ratio and flow plug ratio.This paper specially analyzed the effect of Weissenberg which the gravels in squirm condition of hyper-concentration viscous flows would tend to move vertically, and the formation mechanism of the gravels accumulated at surface was also studied.The analysis in this paper can establish a foundation for the studies on differentiation of bedding structures of debris flow deposits and studies on dynamic parameters of debris flows.

Concentrations and isotopic characteristics of atmospheric reactive nitrogen around typical sources in Beijing,China

With rapid economic growth in China, anthropogenic reactive nitrogen （Nr） emissions have more than doubled over the last two or three decades. Atmospheric Nr pollution is an environmental concern in China especially in megacities such as Beijing. In order to identify the impact of emission sources on atmospheric Nr pollution, we measured atmospheric Nr concentrations and their isotopic composition （δ15N） dynamics at three typical sites： landfill, pig farm and road traffic sites in Beijing from April 2010 to March 2011. Passive samplers were used for monitoring ammonia （NH3） and nitrogen dioxide （NO2）, two major Nr species, while their δ15N values were measured by a diffusion method combined with mass spectrometer approach. The raw water pool of the landfill and fattening house of the pig farm were important NH3 sources with mean NH3 concentrations being 2,829 and 2,369 μg/m3, respectively, while the road traffic site was a minor NH3 source （10.6 μg/m3）. NH3 concentrations at sites besides the landfill and roads were high in summer and low in winter due to the annual variation of temperature and the change of emission source intensity. In contrast, the NH3 concentrations inside the pig farm house were high in winter and low in summer, for the barn windows were open in summer and closed in winter. The mean NO2 concentrations were 89.8, 32.9 and 23.0 μg/m3 at the road traffic, the landfill and pig farm sites, respectively. Due to vehicle fuel combustion, NO2 concentration at the road traffic was the highest among the three sources, and the road traffic was a main NO2 emission source. PM10, pNH4＊ and pNO3- concentrations in particulate matter were higher in summer than in winter （except PM10 for the pig farm）. The δ15NH3 values ranged from -19.14‰ to 7.82‰, with an average of-0.05‰ for the landfill site, and the lowest values were observed in June and July. The δ15NH3 values for the pig farm site ranged from -29.78‰ to-14.05‰ with an average of-24.51‰, and the 515NH3 values were more negative in summer than in the other seasons. The （515NO2 values were -9.63%o to 7.04‰ with an average of -3.72%0 for the road traffic site. The δ15NO2 values were more negative in summer than those in the other seasons. The different δ15N values for the various Nr species in different sources may serve as important indicators for identifying atmospheric Nr sources in megacities. The results may also provide the theoretical basis for research on the atmospheric N deposition and its sources.

Dynamic Appraisal of Water-Soil Safety of Dump in Coal Field

Taking Pingshuo West Dump (247.91 hm2) for example, an evaluating model of water-soil safety was set up according to 8 disaster factors of soil erosion: 30 min rainfall intensity, surface material, landform and slope gradient, cover-degree, topographic, engineering measure grade of conservation of water-soil, volume weight and irregular subsidence. In new stage, early stage and later stage of reclamation, the degree of safety and the different site conditions were analyzed by the model. The results indicat that the dump belongs to middle danger, low danger and low safety in new stage, early stage and later stage of reclamation respectively. But at the same stage, different site conditions lead to different safety class because of the different disaster factors.

Improving the CoLM in Taklimakan Desert Hinterland with Accurate Key Parameters and an Appropriate Parameterization Scheme

Improving and validating land surface models based on integrated observations in deserts is one of the challenges in land modeling. Particularly, key parameters and parameterization schemes in desert regions need to be evaluated in-situ to improve the models. In this study, we calibrated the land-surface key parameters and evaluated several formulations or schemes for thermal roughness length （z 0h ） in the common land model （CoLM）. Our parameter calibration and scheme evaluation were based on the observed data during a torrid summer （29 July to 11 September 2009） over the Taklimakan Desert hinterland. First, the importance of the key parameters in the experiment was evaluated based on their physics principles and the significance of these key parameters were further validated using sensitivity test. Second, difference schemes （or physics-based formulas） of z 0h were adopted to simulate the variations of energy-related variables （e.g., sensible heat flux and surface skin temperature） and the simulated variations were then compared with the observed data. Third, the z 0h scheme that performed best （i.e., Y07） was then selected to replace the defaulted one （i.e., Z98）; the revised scheme and the superiority of Y07 over Z98 was further demonstrated by comparing the simulated results with the observed data. Admittedly, the revised model did a relatively poor job of simulating the diurnal variations of surface soil heat flux, and nighttime soil temperature was also underestimated, calling for further improvement of the model for desert regions.