The influence of uniaxial tensile strain on the pore size and filtration characteristics of geotextiles

The influence of uniaxial tensile strain on the pore size distribution and filtration characteristics of geotextiles is studied. An experimental apparatus was designed and used to conduct tests for pore size distribution, flow rate through the geotextiles and the gradient ratio. Four geotextiles made of polypropylene (two heat-bonded nonwoven and two slit film woven) were studied. Throughout the test series, the geotextiles were stretched to maintain 5%, 10% and 20% in-plane uniaxial strains. The strained specimen test results were compared with those from unstrained specimen. The experimental results illustrate the pore size and the mean flow rate through the plain geotextiles increase with the increase in tensile strain. The differences in changed percentages for apparent opening size and flow rate between the two nonwoven geotextiles are much higher than those between the two woven geotextiles. The increase in tensile strain results in reduction in the gradient ratio for the soil–geotextile system. This effect is more pronounced for nonwoven geotextiles. More testing is recommended to gain a deeper understanding into tensile strain effect on various geotextiles.     

The impact of flow surges on rapid gravity filtration

In drinking water treatment flow fluctuations or surges can occur at the filtration stage. Pilot plant tests were carried out to investigate the impact of flow surges on filter performance in this study. Moreover a filtration model was applied to analyse the impact of flow surges on filter performance and predict the experimental data obtained from pilot plant tests. Experimental results showed that flow surges caused an increase in effluent particle concentration and head loss. Theoretical analysis in this study showed that the impact of a flow surge became more significant as the filtration run approaches the particle breakthrough stage. The model was also used to fit the data from one water treatment plant. The comparison demonstrated a good agreement.     

地下水对引水式电站隧洞围岩稳定性影响的研究

基于大型通用有限元软件ANSYS对引水式水电站引水隧洞开挖与衬砌过程进行数值模拟。隧洞开挖与衬砌采用ANSYS软件中的生死单元来实现。通过模拟隧洞的开挖与衬砌,改变地下水水位,进而对各水位对应下的引水隧洞洞身段围岩及衬砌稳定进行评价。故在计算结果的基础上．结合工程实际情况和经验．研究地下水水位对隧洞围岩稳定性的影响,并得出几点有益的结论,以期为实际隧洞工程施工及设计提供依据。     

A review of the impact of climate change on future nitrate concentrations in groundwater of the UK

This paper reviews the potential impacts of climate change on nitrate concentrations in groundwater of the UK using a Source-Pathway-Receptor framework. Changes in temperature, precipitation quantity and distribution, and atmospheric carbon dioxide concentrations will affect the agricultural nitrate source term through changes in both soil processes and agricultural productivity. Non-agricultural source terms, such as urban areas and atmospheric deposition, are also expected to be affected. The implications for the rate of nitrate leaching to groundwater as a result of these changes are not yet fully understood but predictions suggest that leaching rate may increase under future climate scenarios. Climate change will affect the hydrological cycle with changes to recharge, groundwater levels and resources and flow processes. These changes will impact on concentrations of nitrate in abstracted water and other receptors, such as surface water and groundwater-fed wetlands. The implications for nitrate leaching to groundwater as a result of climate changes are not yet well enough understood to be able to make useful predictions without more site-specific data. The few studies which address the whole cycle show likely changes in nitrate leaching ranging from limited increases to a possible doubling of aquifer concentrations by 2100. These changes may be masked by nitrate reductions from improved agricultural practices, but a range of adaption measures need to be identified. Future impact may also be driven by economic responses to climate change.     

Erratum to “Effects of intensive urbanization on the intrusion of shallow groundwater into deep groundwater: Examples from Bangkok and Jakarta”

Asian megacities have severe pollution problems in both coastal and urban areas. In addition, the groundwater potential has decreased and land subsidence has occurred because of intensive groundwater pumping in urban areas. To prevent the adverse effects of urbanization on groundwater quality, it is necessary to confirm the changes in groundwater flow and contaminant transport caused by urbanization. We examined the effects of urbanization on contaminant transport in groundwater. The research areas were located around Bangkok, Thailand, and akarta, Indonesia, cities with populations of approximately 8 and 12 million, respectively. Each metropolitan city is located on a river delta and is adjacent to a bay. We measured the water level and collected water samples at boreholes at multiple depths (100 to 200 m) in 2004 and 2006 in Bangkok and Jakarta, respectively. The current hydraulic potential is below sea level in both cities because of prior excess abstraction of groundwater. As a result, the direction of groundwater flow is now downward in the coastal area. The Cl⁻ concentration and δ¹⁸O distributions in groundwater suggest that the decline in hydraulic potential has caused the intrusion of seawater and shallow groundwater into deep groundwater. Concentrations of Mn and NO3⁻-N in groundwater suggest the intrusion of these contaminants from shallow to deep aquifers with downward groundwater flow and implies an accumulation of contaminants in deep aquifers. Therefore, it is important to recognize the possibility of future contaminant transport with the discharge of deep groundwater into the sea after the recovery of groundwater potential in the coastal areas.     

Effects of human activities and urbanization on groundwater environments: an example from the aquifer system of Tokyo and the surrounding area

The Kanto plain that is the largest depositional plain in Japan has the largest urbanized area called Tokyo Metropolitan Area. This plain has experienced extensive groundwater withdrawals for water resources and human induced disasters such as land subsidence in the process of urbanization. Japanese national government and local governments have monitored groundwater levels and settlement of ground surface for about half a century. These data are useful not only for the prevention of these disasters but for the evaluation of the change of groundwater flow beneath the urbanized area. However, few hydrological and hydrogeological studies about the change of groundwater flow in this plain have been conducted until now except for several studies which were limited in areal extent. In this paper, changes of the distribution of hydraulic heads in the central part of this plain are discussed using the long-term groundwater level observation data to evaluate the change of groundwater flow. The temporal changes in the distribution of hydraulic heads in a major confined aquifer (the second aquifer) and the areal extent of the urbanized area for approximately 50 years can be summarized as follows. In the latter half of the 1950s, urban area was limited in the southern region of the study area and hydraulic head gradually declined from the northwest to the southeast in the study area. After the 1960s, urban area extended toward the north and groundwater in the northern part was largely abstracted until the 1980s. As a result, hydraulic heads in this area markedly declined. On the other hand, hydraulic heads in the southern part began to rise because of the restriction of groundwater withdrawals. In recent years, low hydraulic head area has been formed from the northern region to the central region. These results suggest that the groundwater flow which was affected by urbanization (groundwater withdrawals) has continued to change over several decades, even after the regulation of withdrawals, and hence, the continued monitoring of the groundwater environment is important for the sustainable use of groundwater resources.     

Model experiments on the microbial removal of chromium from contaminated groundwater

A bacterial consortium with representatives of sulfate-reducing and denitrifying bacteria was selectively enriched. Model experiments under microaerobic conditions showed that it precipitated chromium from Cr (VI)-containing waters (area of a former electroplating factory, Leipzig, Germany) by two different mechanisms: by sulfate reduction and precipitation as sulfide, and by some direct reduction. Sulfate reduction needed fatty acids as organic substrates and resulted at the first stage in no sulfide accumulation. In the absence of the fatty acids but with straw as organic substrate, the direct reduction of chromium was observed without sulfate reduction. In this case Cr (VI)-reduction rate correlated with that of the denitrification.     

Nucleic acid fluorochromes and flow cytometry prove useful in assessing the effect of chlorination on drinking water bacteria

Flow cytometry (FCM), combined with staining using two fluorochromes (propidium iodide, PI, or SYBR Green II RNA gel stain, SYBR-II), was used to assess nucleic acid injuries to chlorinated drinking water bacteria. Highly fluorescent SYBR-II-stained bacteria were converted to bacteria with low fluorescence after chlorination. PI staining of bacteria exposed to different doses of chlorine showed membrane permeabilisation ([Cl2] < 0.2 mg L(-1)) and nucleic acid damage at higher doses ([Cl2] > 0.3 mg L(-1)). Above a threshold dose (between 1.5 and 3 mg Cl2 L(-1)), nucleic acids appeared severely damaged and incapable of being stained by PI or SYBR-II. These results constitute evidence that FCM is a promising tool for assessing drinking water bacteria injuries and for controlling chlorine disinfection efficiency much more rapidly than the standard sensitive but time-consuming heterotrophic plate count method.     

The impact of variable hydraulic operation of water distribution networks on disinfection by-product concentrations

This study assessed the magnitude of variations in the concentrations of disinfection by-products, specifically trihalomethanes and haloacetic acids, which occur in two UK water distribution networks of different sizes due to changes in the hydraulic operation of the networks. These operational changes included varying the fill levels of water storage tanks and pumping conditions within the network. This was investigated through modelling which combined a conventional distribution network flow model (EPANET) with previously developed models for disinfection by-product formation, and using network information obtained from water company partners. The modelling demonstrated that there is the potential for significant variations in disinfection by-product concentrations, up to a 40% change in some simulations, due to what may be considered routine variability in the hydraulic operation of the network. Smaller networks may be especially susceptible to these variations. These findings may influence how water companies plan disinfection by-product monitoring programmes for regulatory reporting.     

The geographic distribution of fluoride in surface and groundwater in Ethiopia with an emphasis on the Rift Valley

This paper analyzes the most extensive database on fluoride distribution in Ethiopia. Of the total 1438 water samples tested, 24.2% had fluoride concentrations above the 1.5 mg/l recommended optimum concentration recommended by WHO. Regionally, by far the highest fluoride levels were recorded in the Rift Valley, where 41.2% of all samples exceeded the 1.5 mg/l level. Only 1.0% of the samples from the central and northwestern highlands and 10.0% in the southeastern highlands exceeded 1.5 mg/l. Larger proportions of deep wells (50.0%) and hot springs (90.0%) than shallow wells (27.2%) and cold springs (12.6%) exceeded the 1.5 mg/l level. The highest fluoride concentrations were recorded for Rift Valley lakes Shala (264.0 mg/l) and Abijata (202.4 mg/l) and the lowest in Lake Tana, and rivers, wells and springs in the highlands. The fluoride concentrations of the Awash River, which originates in the highlands and flows through the Rift Valley, increase downstream, giving concern over the current diversion of high-fluoride water from Lake Beseka. Of the various flourosis prevention methods tried in Ethiopia, the treatment of surface water has been shown to be the most feasible and effective for towns and large commercial farms in the Rift Valley, although defluoridation methods should be considered for smaller rural communities.     

上海松江区人口分布和城市发展策略思考

城镇化是当今中国最重要的经济现象之一,随着经济社会的不断发展,人口日益向城市集中,人口与资源、环境等的矛盾逐渐凸显,如何实现城市人口与城市经济社会相协调发展是城市发展研究的重要内容之一。从城市规划发展的角度研究当前松江区人口分布的特点、形成原因以及存在的问题,并提出与之相应的改菩措施,以期更好地指导松江未来的城市发展和建设。以“六普”人口数据为基础,并采用了在编的《松江区土地利用总体规划2010-2020》、近年松江区和上海市的统计年鉴内的相关数据资料,通过数据的收集和分析和对比来对文本的观点做出科学论证。     

The impact of climate change on the distribution of rural income in Ethiopia

Recent evidence suggests that global climate change is likely to increase the incidence of environmental disasters, as well as the frequency of extreme weather events. As a result, it is generally recognized that climate and weather variability has negative impacts on households’ welfare relying mainly on agriculture. In Ethiopia, 95% of the population depends on rain-fed agriculture and consequently the economic impact of climate change is crucial for small-scale farmers’ food security and welfare. The objective of this study is to provide a comprehensive analysis of the impact of climate change on rural households’ welfare in Ethiopia by using a Quantile Regression (QR) analysis. The main econometric results show that the elasticity of crop income with respect to rainfall varies across quantiles. It is confirmed that there is a non-linear relationship between climatic variables and income.     

某高速公路隧道出口端涌水对地表饮用水源的影响分析

保护饮用水源是隧道建设过程中必须重视的关键问题之一,若处理不当,易引起民众纠纷。本文以某在建高速公路隧道为例,在开展隧道涌水及地表水源点水质和水量动态监测的基础上,通过估算隧道排水的影响范围、分析隧道及水源点流量变化特征和开展隧道涌水来源识别工作,分析得出,隧道建设对水源点M1影响较小,对M2影响最为突出,与M3存在紧密联系,但有明显滞后,当其中之一出现流量增加或减少趋势后,另一者会在地下水系统动态调节并达到新的平衡后出现相反的变化趋势。上述结论可为科学评估隧道施工对饮用水源的影响和向隧道建设单位及有关部门解决因隧道施工而产生的水源纠纷提供科学决策依据。     

The impact of transfers on water quality and the disturbance regime in a reservoir

The effect of water transfers between two reservoirs on the water quality of the receiving reservoir was investigated over a 9-year period (2000-2008). Different management strategies were implemented in term of the magnitude and timing of water transfers, i.e. the amount of transferred volume and the frequency at which transfers occurred. These different operational modes were analysed to determine changes in nutrient and metal concentrations, chlorophyll a, algal genera and biovolume. During high water transfers, chlorophyll a and total algal biovolume increased, with larger diatoms preferentially selected due to the high silica content of the pumped inflow and a significant shift in cyanobacteria genera occurring from Microcystis to nitrogen-fixing genera. The magnitude and timing of water transfers exerted a strong control on phytoplankton competition and disturbed the typical seasonal succession during low pumping years of a spring diatom bloom followed by summer cyanobacteria dominance: intensive and frequent water transfers resulted in dominance by diatoms for the whole year and effectively limited cyanobacteria summer growth. From this analysis, we identified iron concentration and diatom biovolume as the key water quality indicators to be included in any optimal management, able to control the transfer regime from both a water quantity and water quality prospective.     

The impact of politics on the application of the Drinking Water Directive (80/778/EEC)

This paper seeks to address a growing lack of historical knowledge in the water industry of how European Union (EU) water policy has developed and been responded to. It also aims to overcome the lack of comparative studies that explore the role politics has played in the development and application of EU water policy. As a result, this paper develops a historical comparative understanding of how England and Wales and the Republic of Ireland have responded to the Drinking Water Directive (80/778/EEC). It does so from the perspectives of political priority and ideology. Political ideology is shown to have had a greater impact on facilitating the achievement of the Directive's standards in England and Wales. However, it is established that the political priority national governments have accorded compliance has been central to ensuring the application and enforcement of the Directive's standards. Despite the apparent success of political ideology in England and Wales, the paper sounds a note of caution with regard to judging privatisation as being uniformly successful, for it has not, particularly if issues of water charges, customer debt and financial and reporting irregularities are considered.     

南水北调西线工程调水区冻土特征

冻土的存在 ,不仅会对建于该区的建筑物造成危害 ,而且还可能引起塌滑、泥 (石 )流、地面融陷等不良地质现象。本文从分析影响冻土发育的因素入手 ,分析了调水区的冻土类型和分布规律 ,以及冻土的构造及工程地质特征 ,最后简单地预测了冻土的演化趋势     

The impact of using chilled water storage systems on the performance of air cooled chillers in Kuwait

In the air conditioning (AC) industry chilled water storage (CWS) systems are one form of cool thermal storage technology that can be used to time shift the electrical load of the system from the peak day periods to off peak night time periods. In this paper the data for the actual exported and generated electrical energy obtained for the power stations in Kuwait has been used to estimate the electrical energy consumption and the peak electrical load of AC systems. Since the chiller in an air cooled AC system represent more than 75% of the total electrical power consumed by an AC system during the peak demand period, the impact of using CWS systems with alternative operating strategies including partial (load levelling), partial (demand limiting) and full load has been investigated. In our conclusions we estimate that approximately 45% of the total annual exported electrical energy is consumed solely by AC systems as a result of the very high ambient temperatures occurring between March and October. Furthermore, it is estimated AC systems represent about 62% of the peak electrical load. The results demonstrate that CWS can reduce the peak electrical load of a chiller in an air cooled AC system by up to 100% and reduce the nominal chiller size by up to 33% depending upon the operating strategy adopted. This is achieved with only a 4% increase in power consumption of the chiller for all CWS strategies except for full storage where the energy consumption actually decreases by approximately 4%.     

The impact of selected water quality parameters on the inactivation of Bacillus subtilis spores by monochloramine and ozone

Selected water quality parameters-pH, dissolved organic carbon, turbidity (NTU), and temperature-were tested for their potential effects on ozone and monochloramine inactivation of Bacillus subtilis spores. In oxidant demand-free phosphate-buffer, temperature had the strongest influence on inactivation kinetics when using ozone, pH had a smaller but significant impact on B. subtilis spore inactivation with both monochloramine and ozone. Where monochloramine was applied, modeling and experimental measurements confirmed that dichloramine levels were too low to produce significant inactivation effects under these experimental conditions. It was demonstrated that oxidant demand-free phosphate buffer may not be an adequate environmental analogue for inactivation responses in natural waters.     

Long-term impact of water desalination plants on the energy and carbon dioxide balance of Victoria,Australia: a case study from Wonthaggi

In 2007, the state government of Victoria, Australia, announced plans to build a large desalination plant with a capacity of 150 million m³ per year of desalinated water. Currently, the only feasible source for significant expansion of the greenhouse-gas neutral (GGN) energy generation in the state is wind power. A criterion for GGN of a desalination plant has been formulated. In a case of no greenhouse gas contribution from the desalination plant, the criterion is satisfied if the annual growth of the electrical energy generated by GGN sources is around 6–9% for the period 2010–2070. Higher annual growth of 18% for the period 2008–2015, 8% annually for the period 2015–2035 and 6% annual growth thereafter are required if the desalination plant is contributing to the greenhouse-gas balance of the state.     

从分子质量的变化分析臭氧活性炭工艺

为了解臭氧活性炭工艺的机理并优化运行条件,采用臭氧活性炭处理黄浦江原水,分析了原水及经不同工艺单元处理后溶解性有机物 (DOM)分子质量 (MW)的变化。结果表明:黄浦江原水中的DOM主要为小分子有机物;臭氧对大分子有机物的氧化分解作用明显强于对小分子有机物的氧化作用;MW<1ku的有机物经臭氧氧化后则表现出不同程度的增加;混凝、沉淀、过滤对MW>3ku的大分子有机物去除效果较好,而对MW<3ku的小分子有机物去除效果较差;生物活性炭单元能有效去除MW为 3~1ku和MW<1ku的小分子有机物;臭氧氧化与活性炭吸附在去除不同MW有机物的过程中有很好的互补性,从而使该工艺能有效去除原水中的DOM。