华蓥山隧道隧址区水文地球化学特征及涌水来源识别

针对华蓥山隧道施工中可能存在的涌突水问题,本研究在现场水文地质调查,取样测试分析的基础上,对华蓥山隧道隧址区地表水、地下水和隧道涌水的水文地球化学特征进行了分析,并对隧道涌水水源进行了识别。结果表明:隧址区水体的水化学类型主要为HCO_3-Ca和HCO_3·SO_4-Ca型,水质偏弱碱性,水化学成分主要来源于岩石的风化作用;隧址区浅层地下水和地表水联系紧密,大气降水是各水体的主要补给来源;隧址区地下水补给高程为315~1467 m,在东南区域,隧道涌水主要来自三叠系上统须家河组(T_3xj)碎屑含水层和侏罗系中统新田沟组(J_2x)碎屑岩含水层,西北部主要来自三叠系下统嘉陵江组(T_1j)灰岩岩溶含水层。     

A GIS Database for Sustainable Management of Shallow Water Resources in the Tulul al Ashaqif Region, NE Jordan

The Tulul al Ashaqif region is an arid area in northeastern Jordan that contains renewable shallow perched aquifer water. The study of these aquifers has led to better understanding of the recharge process as well as other hydrological issues related to management of water resources in similar areas. The use of geographic information system (GIS)-based predictive mapping to locate areas of high potential for shallow perched aquifer sites is explored in this paper. Knowledge of the hydrologic, geologic and geomorphic variables influencing the development of shallow aquifer formation is used to produce GIS layers representing the spatial distribution of those variables. The GIS layers are then analyzed to identify locations where combinations of environmental variables match patterns observed at known sites. In addition, information can be deduced on the volume of water that is available and the best locations to site recharge facilities. Moreover, future development of these resources requires consideration of possible adverse affects of usage on these resources. The database developed can be used for this purpose as well.     

Updating of a DRASTIC-based Method for Specific Vulnerability Assessment in Carbonate Aquifers

Abstract

Some methodological modifications are suggested to improve a DRASTIC-based method as a reliable predictor of microbial contamination in extensively fractured and subordinately karstified carbonate aquifers. These modifications will allow a better assessment of vulnerability induced by the concentrated infiltration of surface runoff in two different scenarios: (a) when the karst system is entirely located within an unsaturated aquifer and (b) when the karst system is partially located within a saturated medium. The effectiveness of the updated method has been experimentally verified by comparing the vulnerability values with the results of a hydrogeological and microbiological study at a test site.     

“Integrated Water Resources Management: A Reassessment” by Asit K. Biswas

Abstract

A hydrogeological and microbiological study was carried out in Italy in order to verify the effectiveness of a DRASTIC-based method for groundwater vulnerability assessment in carbonate (fractured-karstified) aquifers. The research was developed: (a) by the monitoring of microbial contamination of two springs from January to July 2001 and from December 2002 to March 2003; and (b) by column tests in intact soil blocks, utilizing a collection strain of Enterococcus faecalis. The comparison of the vulnerability map with the results of the microbiological experiments demonstrated the effectiveness of the new DRASTIC-based method as a predictor of groundwater microbial contamination in carbonate aquifers. The effectiveness of the new proposed approach was verified and highlights the diversified role of the diffuse infiltration of precipitations through the fracture pattern and the more or less concentrated infiltration of surface water in karst areas.     

抽水地面沉降中含水层长期变形特性研究

 长江三角洲地面沉降监测数据表明,抽水地面沉降中含水层的变形在总沉降量中占较大比例,且随时间长期发展。分析认为含水层砂土的蠕变是造成其变形长期发展的主要原因,而目前计算砂土蠕变特性的模型中普遍存在参数较多且确定困难的问题。根据含水层砂土的蠕变特性,对采用Singh黏性土蠕变模型计算含水层长期变形的方法进行研究。该模型假定土的蠕变速率与时间在双对数坐标系中呈线性关系,模型中仅有1个参数,即双对数坐标系中蠕变速率与时间曲线的斜率m。砂性土蠕变试验数据统计结果表明,砂性土的m值为0.9～1.1。通过对m的灵敏性分析可知,m在0.9～1.1区间内取值对计算结果影响不大,因此,在缺乏试验数据时可假定m = 1。利用常州和上海的地面沉降实测数据验证Singh模型计算含水层变形的有效性及模型参数简化确定方法的准确性。     

THE 1999 CRYPTOSPORIDIUM RISK ASSESSMENT EXERCISE IN ENGLAND AND WALES- A GROUNDWATER OVERVIEW

Regulations Introduced in 1999 obliged water companies In England and Wales to conduct risk assessments of their treatment works to establish whether there was a significant risk from Cryptosporidium oocysts in the water supplied. More than 330 treatment works were identified as being at risk, just over half of which were plants treating groundwater. This paper provides an overview of what water companies themselves identified as the most at-risk settings for their groundwater-based works in terms of aquifer and type of supply. Evaluation of results from the subsequent continuous monitoring regulatory regime that came into force on many of these supplies could validate the primarily qualitative nature of the initial assessments of at-risk settings. There would also be public health benefits from confirmation of whether currently-employed risk assessment methods are well-founded because similar procedures could then be applied with confidence to the many small private supplies In Britain.     

The effect of natural flow of aquifers and associated dispersion on the onset of buoyancy‐driven convection in a saturated porous medium

Carbon dioxide injection into deep saline aquifers is an important option for managing CO₂ emissions. Injected CO₂ dissolves into formation brines from above, increasing brine density and creating an unstable hydrodynamic state favorable for natural convection. Long‐term buoyancy‐driven flow of high‐density CO₂‐saturated brine leads to faster trapping through improved dissolution and can reduce the risk of CO₂ leakage from storage sites. We investigate the role of natural flow of aquifers and associated dispersion on the onset of convection. A linear stability analysis of a transient concentration field in a laterally infinite, horizontal, and saturated porous layer with steady horizontal flow is presented. The layer is subjected to a sudden rise in CO₂ concentration from the top and is closed from the bottom. Solution of the stability equations is obtained using a Galerkin technique and the resulting equations are integrated numerically. We found simple scaling relationships that follow t_Dc～60(1 + Pe_T)Ra^‐2 for the onset time of convection and a～0.05Ra/(1 + Pe_T) for the wavenumber of the initial instabilities. Results reveal that transverse dispersion increases the time to onset of convection for the entire range of Ra. Furthermore, transverse dispersion decreases the critical wavenumber of the instabilities. These results facilitate screening candidate sites for geological CO₂ storage. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Review of the impact of the 1999 Water Regulation in reducing Cryptosporidium contamination risk in groundwater public supplies

In 2000, the UK introduced a Cryptosporidium oocyst monitoring programme for groundwater public supplies as a consequence of a 1999 amendment to statutory water quality regulations in England and Wales. The programme, which is ongoing and was estimated to have cost c. £12 million (€17.4 million) by the end of 2005, has accumulated the largest and most comprehensive array of data on the presence of oocysts in raw groundwater in the UK to date, with 90 water treatment works subjected to continuous monitoring at one time or another between 2000 and 2005. The programme was preceded by a scrutiny of the future of over 180 groundwater supplies identified as significantly at risk by the 19 water utilities concerned. The results of this process and of the monitoring programme up to 2005 are examined and critically reviewed.     

ESTIMATING RECHARGE FOR BRITISH AQUIFERS

This paper reviews methods of estimating recharge for a wide variety of aquifers in Britain. A soil moisture balance technique is used with direct representation of relevant soil and crop properties. Recharge contributions due to rainfall, runoff from impervious areas and leaking water mains and sewers are considered. In many field situations low permeability strata, which overlie the main aquifer, modify the timing and magnitude of the actual recharge. Runoff from less permeable strata can become runoff-recharge at the aquifer outcrop. Reference is made to several case studies.     

甲烷对超临界CO2/水/岩石体系润湿特性影响的分子动力学模拟研究

二氧化碳捕集及封存(CCS)技术以其减少碳排放量的高效性,成为各国解决碳排放问题的首要选择。通过分子动力学模拟方法,探究了地质封存环境下,在不同岩石结构表面,二氧化碳中混入甲烷对润湿性的影响规律。结果表明:在温度为318.00K、压力为20 MPa的环境下,二氧化碳中混入摩尔分数为20%的甲烷,对水在结构分别为Q~3和(Q~3+Q~4)岩石表面的接触角均无显著影响。