Generating sustainable towns from Chinese villages: a system modeling approach

The great majority of China's developing towns will be extensions of already existing villages. With the prospect of hundreds of millions of Chinese farmers projected to leave their villages to become industrial workers in new and expanded towns within the next few years, new challenges will be faced. As expansion and modernization progress, this development moves from the traditional village model that operates not far from resource sustainability to increasingly unsustainable patterns of commerce, urban development, and modern life. With such an unprecedented mass migration and transformation, how can Chinese culture survive? What is to become of the existing million plus agricultural villages? How can these massively unsustainable new industrial towns survive? In the European Commission sponsored research program SUCCESS, researchers worked from the scale of the Chinese village to find viable answers to these questions.     

Impacts of Multiple Stresses on Water Demand and Supply Across the Southeastern United States1

Abstract: Assessment of long‐term impacts of projected changes in climate, population, and land use and land cover on regional water resource is critical to the sustainable development of the southeastern United States. The objective of this study was to fully budget annual water availability for water supply (precipitation ? evapotranspiration + groundwater supply + return flow) and demand from commercial, domestic, industrial, irrigation, livestock, mining, and thermoelectric uses. The Water Supply Stress Index and Water Supply Stress Index Ratio were developed to evaluate water stress conditions over time and across the 666 eight‐digit Hydrologic Unit Code basins in the 13 southeastern states. Predictions from two Global Circulation Models (CGC1 and HadCM2Sul), one land use change model, and one human population model, were integrated to project future water supply stress in 2020. We found that population increase greatly stressed water supply in metropolitan areas located in the Piedmont region and Florida. Predicted land use and land cover changes will have little effect on water quantity and water supply‐water demand relationship. In contrast, climate changes had the most pronounced effects on regional water supply and demand, especially in western Texas where water stress was historically highest in the study region. The simulation system developed by this study is useful for water resource planners to address water shortage problems such as those experienced during 2007 in the study region. Future studies should focus on refining the water supply term to include flow exchanges between watersheds and constraints of water quality and environmental flows to water availability for human use.     

One-dimensional model for biogeochemical interactions and permeability reduction in soils during leachate permeation

This paper uses the findings from a column study to develop a reactive model for exploring the interactions occurring in leachate-contaminated soils. The changes occurring in the concentrations of acetic acid, sulphate, suspended and attached biomass, Fe(II), Mn(II), calcium, carbonate ions, and pH in the column are assessed. The mathematical model considers geochemical equilibrium, kinetic biodegradation, precipitation-dissolution reactions, bacterial and substrate transport, and permeability reduction arising from bacterial growth and gas production. A two-step sequential operator splitting method is used to solve the coupled transport and biogeochemical reaction equations. The model gives satisfactory fits to experimental data and the simulations show that the transport of metals in soil is controlled by multiple competing biotic and abiotic reactions. These findings suggest that bioaccumulation and gas formation, compared to chemical precipitation, have a larger influence on hydraulic conductivity reduction.     

Hydrochemistry of urban groundwater, Seoul, Korea: the impact of subway tunnels on groundwater quality

Hydrogeologic and hydrochemical data for subway tunnel seepage waters in Seoul (Republic of Korea) were examined to understand the effect of underground tunnels on the degradation of urban groundwater. A very large quantity of groundwater (up to 63 million m³ year^− 1) is discharged into subway tunnels with a total length of 287 km, resulting in a significant drop of the local groundwater table and the abandonment of groundwater wells. For the tunnel seepage water samples (n = 72) collected from 43 subway stations, at least one parameter among pathogenic microbes (total coliform, heterotrophic bacteria), dissolved Mn and Fe, NH₄⁺, NO₃⁻, turbidity, and color exceeded the Korean Drinking Water Standards. Locally, tunnel seepage water was enriched in dissolved Mn (avg. 0.70 mg L^− 1, max. 5.58 mg L^− 1), in addition to dissolved Fe, NH₄⁺, and pathogenic microbes, likely due to significant inflow of sewage water from broken or leaking sewer pipes.Geochemical modeling of redox reactions was conducted to simulate the characteristic hydrochemistry of subway tunnel seepage. The results show that variations in the reducing conditions occur in urban groundwater, dependent upon the amount of organic matter-rich municipal sewage contaminating the aquifer. The organic matter facilitates the reduction and dissolution of Mn- and Fe-bearing solids in aquifers and/or tunnel construction materials, resulting in the successive increase of dissolved Mn and Fe. The present study clearly demonstrates that locally significant deterioration of urban groundwater is caused by a series of interlinked hydrogeologic and hydrochemical changes induced by underground tunnels.     

Seasonal and diurnal gas exchange differences in ozone-sensitive common milkweed (Asclepias syriaca L.) in relation to ozone uptake

Stomatal conductance and net photosynthesis of common milkweed (Asclepias syriaca L.) plants in two different soil moisture regimes were directly quantified and subsequently modeled over an entire growing season. Direct measurements captured the dynamic response of stomatal conductance to changing environmental conditions throughout the day, as well as declining gas exchange and carbon assimilation throughout the growth period beyond an early summer maximum. This phenomenon was observed in plants grown both with and without supplemental soil moisture, the latter of which should theoretically mitigate against harmful physiological effects caused by exposure to ozone. Seasonally declining rates of stomatal conductance were found to be substantial and incorporated into models, making them less susceptible to the overestimations of effective exposure that are an inherent source of error in ozone exposure indices. The species-specific evidence presented here supports the integration of dynamic physiological processes into flux-based modeling approaches for the prediction of ozone injury in vegetation.     

Copper desorption in flooded agricultural soils and toxicity to the Florida apple snail (Pomacea paludosa): implications in Everglades restoration

Copper (Cu) desorption and toxicity to the Florida apple snail were investigated from soils obtained from agricultural sites acquired under the Comprehensive Everglades Restoration Plan. Copper concentrations in 11 flooded soils ranged from 5 to 234 mg/kg on day 0 and from 6.2 to 204 mg/kg on day 28 (steady-state). The steady-state Cu concentration in overlying water ranged from 9.1 to 308.2 microg/L. In a 28-d growth study, high mortality in snails occurred within 9 to 16 d in two of three soil treatments tested. Growth of apple snails over 28 d was affected by Cu in these two treatments. Tissue Cu concentrations by day 14 were 12-23-fold higher in snails exposed to the three soil treatments compared to controls. The endangered Florida snail kite and its main food source, the Florida apple snail, may be at risk from Cu exposure in these managed agricultural soil-water ecosystems.     

泥石流灾害风险评价方法及其应用研究

探讨泥石流灾害风险评价的理论和方法;利用已有的泥石流灾害资料,建立泥石流风险评价体系和实施流程;提出风险评价的定量计算方法;结合遥感和地理信息系统技术,完成了云南省昆明市东川区泥石流灾害的定量风险评价。研究结果与泥石流实际分布和调查资料基本一致,表明所提出的泥石流灾害风险评价的理论与方法具有一定的理论价值和现实意义,可以为泥石流灾害风险评价和防灾减灾管理提供有益的科学依据。     

应急撤离建模研究的现状、问题与发展趋势

分析以往的突发事件应急撤离决策过多依赖决策者主观判断的问题,提出通过构建应急撤离模型为决策者提供更客观的辅助决策信息,并阐述了应急撤离建模过程涉及的主要要素。通过对3种主要应急撤离建模方法——宏观、微观和中观的撤离建模过程的详细介绍和分析,综观了当前应急撤离建模的研究现状。在该基础上,研讨每种建模方法的特点、适用范围以及存在的主要问题,并针对这些问题,给出可能的解决方法和未来的发展方向。归纳应急撤离建模研究的成果,提出在实际应急撤离建模工作中应注意的问题。     

尾矿库溃坝模型探讨

针对尾矿库日常工作中需要对其溃坝可能造成的危害及危害范围进行估计而又没有成熟的模型可用的情况,采用工程类比法,根据泥石流以及水库溃坝等方面的工程经验和数学模型,经过对其相似之处进行类比,并对原有模型进行适当调整,以期得出尾矿库溃坝所形成泥石流的数学模型,并求出其冲击范围和破坏能力,可以为尾矿库的应急管理工作和选址决策提供一个相对成熟和稳定的方法。     

地铁火灾防排烟设计探讨

介绍了防排烟系统设计在地铁火灾中的重要性,以及目前国内地铁车站在防排烟设计中有关排烟量的计算,区间隧道的排烟方式,排烟风亭与出入口之间的位置设计等方面所存在的一些问题及相关的解决方案。结合所引用的相关试验研究及其结论,经过对上述相关问题的分析和总结,针对地铁车站公共区和区间隧道的排烟方式和排烟装置,文章提出了适于国内地铁消防防排烟建设的措施,最后根据所引用的试验,对所提出的措施作出了分析,以得出结论。