汶川县绵虒镇板子沟“8·20”大型泥石流堵河特征及危害性预测

汶川地震后,板子沟曾发生过多次大规模泥石流,尤其是2019年“8·20”泥石流对沟口的道路桥梁以及村寨造成了严重的破坏,将主河道向对岸严重挤压,今后仍存在较大堵河的风险。文章在野外调查以及对泥石流基本特征和形成条件综合分析的基础上,分析了堵河特征,计算了不同频率下泥石流的堵河参数,并预测了各频率下溃决洪水对绵虒镇可能产生的影响。计算结果表明,频率为2％、5％和10％的泥石流造成岷江堵塞的可能性较小,假设发生堵河事件,绵虒镇也不会受到溃坝洪水的危害。频率为1％的泥石流很可能造成主河堵塞。体积约57.38×104 m3的泥石流物质可以到达岷江,形成高度约为51.61 m的堰塞坝。在主河洪水的作用下,堰塞坝发生溃坝,溃坝洪水的峰值流量为5 935.49 m3/s,到达绵虒镇后降至2 312.25 m3/s。由于相应的洪水深度（4.00 m）大于防护堤的高度（3.50 m）,因此溃坝洪水很可能会对绵虒镇防护堤附近民房造成破坏。为今后大型泥石流堵河特征的分析,以及溃决洪水对下游城镇可能造成的影响提供了参考。     

宝兴县中岗沟824泥石流成因及冲淤特征研究

2013年8月24日18点左右,雅安市宝兴县永富乡局地形成强降雨,强降雨过程历时6个小时,并于当日晚10点30分左右中岗沟发生了大规模泥石流灾害,泥石流过程历时约1.5h。通过对2013年8月24日中岗沟泥石流的野外实地调查,分析了泥石流的基本特征、成因、冲淤特征及其成灾模式等。     

Distributed discharge and sediment concentration predictions in the sub‐humid Ethiopian highlands: the Debre Mawi watershed

Experimental research in the Ethiopian highlands found that saturation excess induced runoff and erosion are common in the sub‐humid conditions. Because most erosion simulation models applied in the highlands are based on infiltration excess, we, as an alternative, developed the Parameter Efficient Distributed (PED) model, which can simulate water and sediment fluxes in landscapes with saturation excess runoff. The PED model has previously only been tested at the outlet of a watershed and not for distributed runoff and sediment concentration within the watershed. In this study, we compare the distributed storm runoff and sediment concentration of the PED model against collected data in the 95‐ha Debre Mawi watershed and three of its nested sub‐watersheds for the 2010 and 2011 rainy seasons. In the PED model framework, the hydrology of the watershed is divided between infiltrating and runoff zones, with erosion only taking place from two surface runoff zones. Daily storm runoff and sediment concentration values, ranging from 0.5 to over 30 mm and from 0.1 to 35 g l^?1, respectively, were well simulated. The Nash Sutcliffe efficiency values for the daily storm runoff for outlet and sub‐watersheds ranged from 0.66 to 0.82, and the Nash–Sutcliffe efficiency for daily sediment concentrations were greater than 0.78. Furthermore, the model uses realistic fractional areas for surface and subsurface flow contributions, for example between saturated areas (15%), degraded areas (30%) and permeable areas (55%) at the main outlet, while close similarity was found for the remaining hydrology and erosion parameter values. One exception occurred for the distinctly greater transport limited parameter at the actively gullying lower part of the watershed. The results suggest that the model based on saturation excess provides a good representation of the observed spatially distributed runoff and sediment concentrations within a watershed by modelling the bottom lands (as opposed to the uplands) as the dominant contributor of the runoff and sediment load. Copyright © 2014 John Wiley & Sons, Ltd.     

Response of Spartina alterniflora Vegetation to Oiling and Burning of Applied Oil

A field study evaluated Spartina alterniflora sensitivity to oiling and to in situ burning of applied crude oil. Experimental plots (2.4 m × 2.4 m × 0.6 m) were constructed in the salt marsh for control, oiling (natural clean-up) and oiling/burning treatments. South Louisiana Crude was applied to oiling and oiling/burning treatment plots at 2 l m⁻² and the burn conducted. S. alterniflora responses (height, live stem density, carbon fixation and biomass) were measured for 50 weeks after the August burn. Oiling and oiling/burning had short-term detrimental effects on the salt marsh. One year after the late summer burn, S. alterniflora responses measured in the oiled and oiled/burned plots were not significantly different compared to control values. Results suggest that, under our experimental conditions, intervention may not be required for marsh recovery. However, if spill conditions require a rapid response to control contaminant spread or protect other sensitive resources, burning may be a clean-up operation to consider.     

我国土壤中铜的污染现状与修复研究进展

铜是动植物必需的微量营养元素,但过量的铜会严重影响动植物的生长。近年来,随着工农业的迅速发展,土壤铜污染已成为重要的土壤环境污染问题之一。土壤铜污染不仅降低土壤环境质量,而且影响植物、土壤微生物、土壤酶活性等的平衡稳定发展,并威胁农产品质量安全。文中综述现阶段我国土壤铜污染的来源、污染现状,分析了土壤铜污染的特点及对土壤生态系统的危害,介绍土壤铜污染的预防方法,分析并总结目前用于治理土壤铜污染的修复技术原理、适用性及其国内外研究与发展动态,进一步提出未来我国土壤铜污染修复技术有待深入研究的相关问题,以期为我国土壤铜污染的研究和修复治理提供参考。     

城乡一体化发展下的土地整治规划环境影响评价——以山东省诸城市为例

土地整治环境影响评价是土地整治规划编制过程中的一个重要环节,目前的土地整治环境影响评价多是从某方面评价土地整治规划对环境的影响。在城乡一体化发展的背景下,按照"全域规划、全域整治"的要求,通过识别土地整治规划对经济、社会和环境影响,建立评价指标体系,以山东省诸城市为例,对土地整治规划环境影响进行综合评价。     

基于RS和GIS的松辽平原黑土流失研究

基于RS和GIS技术,利用1986年TM数据和2001年ETM数据,对松辽平原黑土分布现状与动态变化进行监测研究,分析了黑土流失特点及其时空分布规律,并引入冲沟线密度概念量化黑土流失趋势。结果表明:松辽平原典型黑土面积54 989.92 km2,沿京哈铁路线呈弧形条带状展布;1986~2001年间,黑土区水土流失面积达3 765.21 km2,减少速度为251.01 km2/a,集中在河流两岸、较大建筑用地附近和与盐碱土接壤的地区;仅考虑冲沟的有效作用域,预计到2016年黑土面积平均会有1411.0 km2/a转变为冲沟,黑土流失状况不容乐观。     

Hydrochemical characterization of an acid mine drainage-affected reservoir: the Sancho Reservoir,Huelva, southwest Spain

Abstract

The objectives of this study were to discover the relationship between variables in a water reservoir and the hydrochemical variations related to acid mine drainage (AMD), and to describe the horizontal stratification related to vertical salinity and variations in metals present in the region. The information obtained may be used for establishing risk evaluation criteria and to design future remediation strategies, which could be useful for new dams. The hydrochemical characterization was based on a sampling campaign performed in October 2011. A total of 28 samples, at 1-m-deep intervals, were obtained. The hydrogeochemical study of the polluted reservoir shows that the dilution effect is not sufficient to neutralize AMD contributions from mining activity. Sampling carried out from the surface water to the deepest points reveals stratification of the reservoir that allows it to be included in the group of monomictic and holomitic lakes.

Editor D. Koutsoyiannis; Associate editor M.D. Fidelibus     

Modeling the Permeability Loss of Metallic Iron Water Filtration Systems

Over the past 30 years the literature has burgeoned with in situ approaches for groundwater remediation. Of the methods currently available, the use of metallic iron (Fe⁰) in permeable reactive barrier (PRB) systems is one of the most commonly applied. Despite such interest, an increasing amount of experimental and field observations have reported inconsistent Fe⁰ barrier operation compared to contemporary theory. In the current work, a critical review of the physical chemistry of aqueous Fe⁰ corrosion in porous media is presented. Subsequent implications for the design of Fe⁰ filtration systems are modeled. The results suggest that: (i) for the pH range of natural waters (>4.5), the high volumetric expansion of Fe⁰ during oxidation and precipitation dictates that Fe⁰ should be mixed with a non‐expansive material; (ii) naturally occurring solute precipitates have a negligible impact on permeability loss compared to Fe⁰ expansive corrosion; and (iii) the proliferation of H₂ metabolizing bacteria may contribute to alleviate permeability loss. As a consequence, it is suggested that more emphasis must be placed on future work with regard to considering the Fe⁰ PRB system as a physical (size‐exclusion) water filter device.     

Modeling discrete gas bubble formation and mobilization during subsurface heating of contaminated zones

During thermal remediation the increase in subsurface temperature can lead to bubble formation and mobilization. In order to investigate the effect of gas formation on resulting aqueous concentrations, a 2D finite difference flow and mass transport model was developed which incorporates a macroscopic invasion percolation (MIP) model to simulate bubble expansion and movement. The model was used to simulate three soil scenarios with different permeabilities and entry pressures at various operating temperatures and groundwater velocities. It was observed that discrete bubble formation occurred in all three soils, upward mobility being limited by lower temperatures and higher entry pressures. Bubble mobilization resulted in a different aqueous mass distribution than if no discrete gas formation was modeled, especially at higher temperatures. This was a result of bubbles moving upwards to cooler areas, then collapsing, and contaminating previously clean zones. The cooling effect also led to possible non-aqueous phase liquid (NAPL) formation which was not predicted using a model without discrete bubble formation.