Environmental impact assessment of risk associated with groundwater overdraft remediation in cone of depression,Jining, China

In this paper, a simple scenario and probabilistic approach is used to assess the potential groundwater risk due to proposed overdraft remedial actions in cone of depression, Jining City, China. Focusing on the concentrations of Chloride ions (Cl⁻) and total hardness (TH), the impact of artificial recharge and reduced pumping on groundwater quality and quantity is analysed by using the three-dimensional finite difference groundwater flow and transport model, Visual MODFLOW, to simulate groundwater flow and transport within the study area based on scenarios, and utilizes SURFER software to map risk levels. Although 5, 10 or 15% reduced pumping with artificial recharge leads to more decrease in Cl⁻ and TH concentrations than the 25%, less volume increase is achieved for the remediation of land subsidence and other environmental problems in the cone of depression. The Cl⁻ concentrations in recovered groundwater are within the desired concentration of 200 mg/l; however, TH in some cases are above the maximum permissible limit of 500 mg/l, with an exceedence probability of about 0.67 for recharge and recharge with reduced pumping at 25%. The presence of fractures and hydrogeological complexity greatly determines impacts of remediation, and the 22% reduced pumping with artificial recharge offers an optimum strategy for overdraft remediation in the Jining cone of depression.     

Pedotransfer functions to estimate soil water content at field capacity and permanent wilting point in hot Arid Western India

Characterization of soil water retention, e.g., water content at field capacity (FC) and permanent wilting point (PWP) over a landscape plays a key role in efficient utilization of available scarce water resources in dry land agriculture; however, direct measurement thereof for multiple locations in the field is not always feasible. Therefore, pedotransfer functions (PTFs) were developed to estimate soil water retention at FC and PWP for dryland soils of India. A soil database available for Arid Western India (N=370) was used to develop PTFs. The developed PTFs were tested in two independent datasets from arid regions of India (N=36) and an arid region of USA (N=1789). While testing these PTFs using independent data from India, root mean square error (RMSE) was found to be 2.65 and 1.08 for FC and PWP, respectively, whereas for most of the tested ‘established’ PTFs, the RMSE was >3.41 and >1.15, respectively. Performance of the developed PTFs from the independent dataset from USA was comparable with estimates derived from ‘established’ PTFs. For wide applicability of the developed PTFs, a user-friendly soil moisture calculator was developed. The PTFs developed in this study may be quite useful to farmers for scheduling irrigation water as per soil type.     

Hybridization of the probability perturbation method with gradient information

Geostatistically based history-matching methods make it possible to devise history-matching strategies that will honor geologic knowledge about the reservoir. However, the performance of these methods is known to be impeded by slow convergence rates resulting from the stochastic nature of the algorithm. It is the purpose of this paper to introduce a method that integrates qualitative gradient information into the probability perturbation method to improve convergence. The potential of the proposed method is demonstrated on a synthetic history-matching example. The results indicate that inclusion of qualitative gradient information improves the performance of the probability perturbation method.     

A coupling of mixed and continuous Galerkin finite element methods for poroelasticity II: the discrete-in-time case

In this paper, we formulate a finite element procedure for approximating the coupled fluid and mechanics in Biot’s consolidation model of poroelasticity. Here, we approximate the pressure by a mixed finite element method and the displacements by a Galerkin method. Theoretical convergence error estimates are derived in a discrete-in-time setting. Of particular interest is the case when the lowest-order Raviart–Thomas approximating space or cell-centered finite differences are used in the mixed formulation and continuous piecewise linear approximations are used for displacements. This approach appears to be the one most frequently applied to existing reservoir engineering simulators.     

Speciation and potential remobilization of heavy metals in sediments of the Taihu Lake, China

The species of Cu, Pb, Zn, Cd and Cr in sediments of the Taihu Lake, China, have been analyzed using the sequential chemical extraction method. Variations in the chemical fractions of these metals and their geographic distributions have also been studied. For all five metals, the residual fraction is highest but the exchangeable fraction is lowest among all the fractions. Compared to other metals, Cd has the highest percentage in the exchangeable fraction, and Cr is associated mainly with the residual fraction. Cu in the organic fraction and Pb in the Fe-Mn fraction are the important species, whereas the lowest percentages are found for Cd in the organic fraction, Cu in the Fe-Mn oxide fraction and Pb in the carbonate fraction. With respect to spatial differences, the total contents in the non-residual fractions of the metals in bay sediments are found to be higher than those in other sediments. The fractions of Cd, Cu and Cr showed significant variations in different regions. The fractions of Pb and Zn, however, did not show significant variations in spatial distribution, suggesting different amounts and different paths of anthropogenic input for the metals. Comparisons of the metal speciation indicated that Cd might be the most bioavailable metal, followed by Pb.     

Oceanography of Glacier Bay,Alaska: Implications for biological patterns in a glacial fjord estuary

Alaska, U.S.A, is one of the few remaining locations in the world that has fjords that contain temperate idewater glaciers. Studying such estuarine systems provides vital information on how deglaciation affects oceanographic onditions of fjords and surrounding coastal waters. The oceanographic system of Glacier Bay, Alaska, is of particular interest ue to the rapid deglaciation of the Bay and the resulting changes in the estuarine environment, the relatively high oncentrations of marine mammals, seabirds, fishes, and invertebrates, and the Bay’s status as a national park, where ommercial fisheries are being phased out. We describe the first comprehensive broad-scale analysis of physical and iological oceanographic conditions within Glacier Bay based on CTD measurements at 24 stations from 1993 to 2002. easonal patterns of near-surface salinity, temperature, stratification, turbidity, and euphotic depth suggest that freshwater nput was highest in summer, emphasizing the critical role of glacier and snowmelt to this system. Strong and persistent tratification of surface waters driven by freshwater input occurred from spring through fall. After accounting for seasonal nd spatial variation, several of the external physical factors (i.e., air temperature, precipitation, day length) explained a large mount of variation in the physical properties of the surface waters. Spatial patterns of phytoplankton biomass varied hroughout the year and were related to stratification levels, euphotic depth, and day length. We observed hydrographic atterns indicative of strong competing forces influencing water column stability within Glacier Bay: high levels of freshwater ischarge promoted stratification in the upper fjord, while strong tidal currents over the Bay’s shallow entrance sill enhanced ertical mixing. Where these two processes met in the central deep basins there were optimal conditions of intermediate tratification, higher light levels, and potential nutrient renewal. These conditions were associated with high and sustained hlorophylla levels observed from spring through fall in these zones of the Bay and provide a framework for understanding he abundance patterns of higher trophic levels within this estuarine system.     

黄土的独立物性指标及其与湿陷性参数的相关性分析

黄土的湿陷性是其重要的工程特性,常用一维压缩应力条件下的湿陷系数、自重湿陷系数和湿陷起始压力等指标定量评价。影响黄土湿陷性的因素较多,包括土的粒度、密度、湿度等基本物理性质指标,且各因素之间并非完全独立,存在一定相关性。采用因子分析法,通过对西安地铁4号线黄土高台地和宝鸡-兰州高速铁路隧道黄土塬湿陷性黄土场地地层物性质指标的统计分析和相关性分析,首先确定了相对独立的含水比（含水率与液限之比）和孔隙比3个物性指标反映的两个因子。然后,依据湿陷性黄土场地的试验资料,通过多元线性回归分析,分别得到了两个场地黄土的自重湿陷系数、湿陷起始压力以及压缩模量与含水比和孔隙比之间的相关关系。最后,比较分析了两个场地黄土自重湿陷系数、湿陷起始压力和压缩模量计算值与实测值,验证了利用因子分析法寻找影响黄土湿陷性的独立因子,建立黄土湿陷性参数与独立影响因子之间相关关系的合理性和准确性。针对两个地区两类地貌单元湿陷性黄土场地,建立的黄土湿陷性参数的相关关系具有快速、准确的评价黄土湿陷性和黄土地基湿陷变形的实际意义。     

Women’s use of public space and sense of place in the Raval (Barcelona)

This article deals with women's use of public space and sense of place in El Raval, a neighbourhood located in the historical center of Barcelona. Attention will be paid to discover to what degree the existence of a quality public space fosters the creation of socially meaningful places, thus contributing to the construction of womens sense of place and urban identities. A qualitative approach, based on direct observation and in-depth interviews with women living in the neighbourhood, has allowed us to capture the main aspects of the building of a sense of place and belonging, that is the use of public space and facilities, the attitude towards living in the neighbourhood, etc. This revised version was published online in July 2006 with corrections to the Cover Date.     

Migration Fractionation of Neutral Nitrogen Compounds of Crude Oils from Tabei Oilfield in the Tarim Basin, China

The absolute amounts and relative distributions of neutral nitrogen compounds in the Tabei oilfield (e. G. Blocks Ln1-Ln1 1) showed remarkable migration fractionation in the vertical direction. From Ordovician reservoirs (O) to oil legs TⅢ and T Ⅰ of Triassic reservoirs in blocks LN1-LN11, the concentrations of [a] [c] decreased from 1. 59μg/g, 0.49μg/g to 0.17 μg/g (oil). The ratios of various alkylcarbazole isomers, such as 1,8-dimethylcarbazole/nitrogenpartially shielded isomers and 1,8-dimethylcarbazole/nitrogen-exposed isomers, were adopted as the indicators of petroleum migration. The ratios increased from 0.13, 0.20 to 0.67 and from going from the south to the north of the Tabei oilfield, the absolute concentrations of neutral nitrogen compounds decreased drastically, and the nitrogen-shielded isomers were enriched relative to nitrogen-exposed isomers and nitrogen-partially shielded isomers. Crude oils in the Tabei oilfield migrated laterally from the Jilake structure to the Sangtamu fault uplift and Lunnan fault uplift, and crude oils in the same fault uplift migrated and remigrated vertically from Ordovician reservoirs, to oil legs TⅢ to TⅠ of Triassic reservoirs.