深基坑地下室防排结合式防水设计和施工

正某高层建筑地下4层(局部2层),地上41层。基坑开挖深度20.32m,最深达25.95m,地下连续墙与地下室外墙两墙合一,墙厚1.0m,地下室结构防水等级为一级。拟建场地浅部地下水属潜水类型,受大气降水及地表径流补给,承压水主要为深部第7层、第9层承压含水层,承压水埋深分别约为7.2m和14.8m,水位呈周期性变化,幅度一般在3.0~12.0m。本地区平均高水位埋深     

基于改进模型的辽东湾东岸营口海域海底地下水排泄量计算

海底地下水排泄(SGD)是全球水循环的重要组成部分,也是向海洋输送营养盐等各类化学物质的必要途径之一。以辽东湾东部营口海域为研究对象,以天然镭同位素(²²⁴Ra、²²⁸Ra)作为示踪剂,建立镭质量平衡模型并加以改进,进而探讨再循环海水(RSGD)对研究区内水体刷新时间、SGD及携带氮磷营养盐通量的影响程度。结果表明:利用镭质量平衡模型计算水体刷新时间为9 d,改进后的镭质量平衡模型计算出的水体刷新时间为14.35~18.11 d;传统模型下SGD通量为(3.01~3.51)×10⁸ m³/d。改进模型评估的SGD通量为(3.55~4.39)×10⁸ m³/d,改进模型评估的水体刷新时间与SGD均明显高于初始模型,其中水体刷新时间增加了59.44%~101.22%;SGD通量增加了17.94%~25.07%。在此基础上,地下水向海输入的氮、磷营养盐通量在考虑RSGD的情况下分别为1.73×10⁸、1.52×10⁹ mol/d。研究结果证明了RSGD对SGD和营养盐通量存在较大影响,为营口海域生态环境评估提供了基础数据。     

南昌市主城区供水水文地质特征研究

研究区地处赣、抚河流冲积平原区,潜水为研究区开采主要含水层,潜水径流主要受地貌形态的控制。潜水含水层的补给主要是河流侧向补给、大气降水的入渗及第三系红层越流补给,丰水期赣江、抚河水补给地下水为主,枯水期以地下水往河流排泄为主;平水期,地表水与地下水交替补排。赣抚流域为典型的硅酸盐地区,地下水水化学受硅酸盐、碳酸盐及人类活动影响,研究区粘土层较厚,湖水对地下水影响不大。人工开采是地下水的主要排泄途径,近年来地下水水井不断减少,但以南钢为中心的降落漏斗最大可达10 m,影响范围较大。     

悬挂式止水帷幕圆形基坑承压含水层地下水非稳定流计算

针对悬挂式止水帷幕基坑中复杂的地下水流动,建立了考虑止水帷幕的圆形基坑承压含水层地下水非稳定流动计算模型。通过对地下水流动计算模型的Laplace变换和有限Fourier余弦变换,推导了Laplace空间的水头降深解,采用Stehfest数值逆变换提出了悬挂式止水帷幕圆形基坑承压含水层地下水非稳定流水头降深半解析解。在验证计算方法正确性和数值逆变换计算准确性的基础上,利用工程实例验证了计算方法的工程适用性。分析了悬挂式止水帷幕插入深度对圆形基坑地下水流动的影响规律,阐明了止水帷幕对基坑内外地下水控制的积极作用,为合理开展悬挂式止水帷幕圆形基坑承压含水层的减压降水设计提供了计算方法。     

陡河流域地表水与地下水转化关系

通过对陡河流域地表水-地下水水样的氢氧同位素分布特征进行分析,发现研究区河岸带第Ⅰ含水层除了受大气降水、灌溉回归水入渗补给外,还接受河水早期的渗漏补给,第Ⅱ含水层对第Ⅲ含水层有越流补给,第Ⅱ含水层同时也受大气降水和灌溉回归水的影响,而远离河岸带的第Ⅳ含水层与上覆各含水层稳定同位素组成显著不同,河岸带水库附近的第Ⅳ含水层可能受地表水库渗漏影响。河岸带地下水与地表水水力联系的变迁严格受河岸带地下水水位变化控制,如景庄子剖面的地下水埋深为5m,雨季时河水补给地下水,旱季时地下水补给河水,而靠近地下水漏斗中心的越河乡剖面地下水水位埋深达25m,其常年受地表水补给。     

抽-灌同轴非完整井承压层非稳定流模型及解析解

对承压含水层在抽-灌同轴非完整井的抽、灌水作用下产生的地下水三维非稳定流建立了数学模型,应用Laplace变换、分离变量法以及井周边界条件傅里叶级数延拓的方法,推导得到考虑越流补给、各向异性条件以及在周期性循环抽水和灌水作用下的地下水水位变化的解析表达式。该解能够退化为考虑越流条件的Hantush非完整井流解析解、第一类越流定流量完整井解和Theis公式。通过算例,在恒定抽水和灌水速率情况下,分析了灌水与抽水速率比、灌水井滤壁长度对承压层水位变化规律及其沿厚度方向和径向分布的影响;在周期性抽水和灌水条件下,分析了承压层水位周期性波动变化的一些规律。     

Kalman滤波技术校正地下水充系统确定——随机性数值模型在大庆地区的应用（下）

(上接本刊 2 0 0 1年 2期第 2 8页 )2　应用ｋａｌｋｍａｎ滤波技术校正地下水流系统确定随机性数值模型实例2 1　地下水流系统数学模型研究区面积约 80 0 0ｋｍ2 ,主要取水层位为第三系承压含水层。历经三十多年的开采 ,已形成了 40 0 0ｋｍ2 的地下水位降落漏斗 ,并积累了大量的动态资料。研究区东部为第三系承压水缺失边界 ,南部、西部和北部为已知水头边界。研究区地下水径流方向为北北西向 ,主要补给方式为侧向径流补给 ,其次为垂向补给 ,主要排泄方式为人工开采 ,依据上述含水层系统特征 ,研究区渗流问题的数学模型可描述为 : ｘ(Ｋ…     

三家店水库水文地质特征及其对工程施工的影响

本文研究了在地表水体长期作用下粗颗粒地层的渗透规律,突破水文地质学中“含水层”和“隔水层”的传统定义,首次提出“饱水层”的概念。浅层地下水的排泄以垂向渗流为主,深层地下水排泄以径流为主;浅层地下水的补给以地表水补给为主,深层地下水的补给主要是浅层地下水通过非饱水带对其补给。分析了水文地质条件对北京市西六环路基挡土墙施工的重要影响。     

江汉平原地下水位动态变化特征分析

通过辨识江汉平原含水系统的水文地质结构,深入分析了地下水位动态变化特征及其影响因素,进而揭示了研究区地下水时空演变规律。结合地下水流系统分区分析了研究区的降雨-径流关系和地下水动态类型。同时,运用数理统计方法分析了累计水位升幅和累计降雨量之间的关系。结果表明:研究区内地表水除丰水期补给地下水外,其余时段地下水补给地表水;研究区不同含水层地下水位关系总体为深层孔隙承压水位中层孔隙承压水位浅层孔隙潜水位;研究区地下水对降雨入渗产生的滞后效应表现为低水位期滞后5~7 d,高水位期滞后1~2 d。研究结果对该地区地下水资源的评价管理具有现实意义。     

东光县地下水压采效果及环境影响预测

运用Visual-MODFLOW软件建立东光县地下水流数值模型,对不同压采方案下地下水水位回升效果进行预测,并分析其环境影响。结果表明:仅压采深层地下水(方案1)时,承压含水层水位整体明显抬升,升幅为2.0~11.7 m,其中处于超采区的东光县城区升高幅度最大;同时压采浅层和深层地下水(方案2)时,承压含水层水位增幅在1.4~11.6 m,城区水位增幅依然最大。两种压采方案对潜水含水层的影响有限,潜水位前期出现不同程度的波动,后期水位较为平稳。总体上,两种方案下整个区域主要潜水位埋深为3~4 m;方案2下,个别地段水位埋深为1.8 m,低于本区防盐碱化临界水位埋深2.0 m,可能造成次生盐碱化风险。     

Groundwater Response to Tidal Fluctuation in an Inhomogeneous Coastal Aquifer-Aquitard System

This paper investigates tide-induced groundwater fluctuation and submarine groundwater discharge (SGD) in a leaky inhomogeneous coastal aquifer system with an upper unconfined aquifer, a lower confined aquifer, and an aquitard between them. The upper left aquifer is formed due to land reclamation. The SGD defined as the groundwater flow from land into the sea is controlled mainly by the hydraulic gradient between land and sea. An analytical expression is developed to discuss and assess the effect of inhomogeneity on the groundwater head fluctuation in the leaky aquifer system. Joint effects of aquifers’ parameters such as leakage and hydraulic diffusivity on the groundwater head fluctuation and SGD are investigated. The predicted results from the analytical expression indicate that the groundwater head fluctuation in both unconfined and confined aquifers is dependent on dimensionless leakages and increases with dimensionless hydraulic diffusivity.     

Simulating Future Groundwater Recharge in Coastal and Inland Catchments

Groundwater is a primary source of drinking water in the Mediterranean, however, climate variability in conjunction with mismanagement renders it vulnerable to depletion. Spatiotemporal studies of groundwater recharge are the basis to develop strategies against this phenomenon. In this study, groundwater recharge was spatiotemporally quantified using the Soil and Water Assessment Tool (SWAT) in one coastal and one inland hydrological basin in Greece. A double calibration/validation (CV) procedure using streamflow data and MODIS ET was conducted for the inland basin of Mouriki, whereas only ET values were used in the coastal basin of Anthemountas. Calibration and simulation recharge were accurate in both sites according to statistical indicators and previous studies. In Mouriki basin, mean recharge and runoff were estimated as 16% and 9%, respectively. In Anthemountas basin recharge to the shallow aquifer and surface runoff were estimated as 12% and 16%, respectively. According to the predicted RCP 4.5 and 8.5 scenarios, significant variations in groundwater recharge are predicted in the coastal zone for the period 2020–2040 with average annual recharges decreasing by 30% (RCP 4.5) and 25% (RCP 8.5). Variations in groundwater recharge in the inland catchment of Mouriki were insignificant for the simulated period. Anthemountas basin was characterized by higher runoff rates. Groundwater management in coastal aquifers should include detailed monitoring of hydrological parameters, reinforced groundwater recharge during winter and reduced groundwater abstraction during summer depending on the spatiotemporal distribution of groundwater recharge.

     

Quantifying natural recharge characteristics of shallow aquifers in groundwater overexploitation zone of North China

To improve the accuracy of hydrological simulations in the groundwater overexploitation zone of North China, it is necessary to study the characteristics of shallow aquifer recharge on daily scale. Three shallow aquifer recharge indices were used to quantify shallow aquifer recharge in two ways. The recharge coefficient was used to quantify the amount of shallow aquifer recharge. The recharge duration and water table rise coefficient were used to quantify the recharge temporal process. The Spearman rank correlation coefficient and regression analysis were used to determine the relationships between aquifer water table depth (WTD), rainfall, and shallow aquifer recharge. The Jiangjiang River Basin, a tributary of the Haihe River, was selected as the study area. The results showed that the recharge coefficient first increased, then decreased, and finally leveled off as WTD increased. When WTD was between 5 and 6 m, the recharge coefficient reached its maximum (approximately 0.3). When WTD was greater than 10 m, the recharge coefficient remained stable (around 0.12). With regard to the sources and forms of recharge, preferential flow was dominant in the areas near the extraction wells. In contrast, plug flow became dominant in the areas distant from the wells. With the reduction of rainfall duration, the proportion of preferential flow contributing to aquifer recharge increased. With the increase of rainfall amount, the duration of aquifer recharge lengthened.     

Groundwater Resources and Human Impacts in a Quaternary Intramontane Basin (L'Aquila Plain,Central Italy)

Abstract

An aquifer vulnerability study was carried out in the L'Aquila Plain of Central Italy for evaluating changes in groundwater quantity and quality induced by human activities. The L'Aquila Plain, filled with Quaternary clastic deposits, is an intramontane basin encircled by karst massifs characterized by regional groundwater, which is connected with the porous multilayer aquifer of L'Aquila Plain. The study was organized into different steps: (1) geo-lithological characterization; (2) sampling of hydrogeological data and water budget evaluation; and (3) hydrochemical and microbiological monitoring of springs and wells. The latter step made it possible to identify water-rock interaction, groundwater mixing and recharge, and to recognize the different sources of groundwater pollution. The plain aquifer, mainly recharged by the surrounding carbonate massifs, shows centripetal groundwater flowpaths. The hydrochemical features show two groundwater end-members, coming from carbonate aquifers or circulating only in the plain, with intermediate mixed groundwater. The observed ground-water pollution is negligible, but it will probably increase if the strong development of the human activities continues without groundwater protection planning.     

Statistical Approach for Comprehensive Planning of Watershed Development Through Artificial Recharge

The purpose of the study is to demonstrate that cross-correlation analyses can contribute to the artificial recharge study in regional level of shallow aquifer. Correlations between hydrologic time series data were analyzed to identify the hydrogeologic location for potential artificial recharge in district Surat, Gujrat, India. The natural groundwater-level fluctuations and rainfall data were used for the analyses. The effective development of groundwater resources is essential for a country like India. India receives a good amount of average annual rainfall (114?cm) but most of its part goes waste as runoff. Over exploitation of groundwater due to increasing population is an additional cause of water crisis that results in the reduction in per capita availability of water in the country. Artificial recharge is essential for effective development of groundwater resources. An effort has been made to evaluate the suitable recharge zone considering rainfall by arresting runoff to restore groundwater conditions using a statistical technique. Groundwater system in a basaltic terrain where the top weathered regolith forms shallow aquifer the water table variation is directly influenced with temporal rainfall variation. Understanding of this relation is of critical importance to management of groundwater resources. A diagnostic relationship between recharge time series and water level time series is used to serve the purpose to determine the best site for groundwater recharge.     

Post Audit Analysis of a Groundwater Level Prediction Model in Developed Semiconfined Aquifer System

This paper assesses groundwater recharge under conditions of long-term groundwater pumping at the Ravnik pumping site in Croatia and analyses the groundwater level prediction model used in prior aquifer modelling. The results of model calibration revealed a very low net infiltration rate at the start of the pumping site’s operation. As the operation continued, the net infiltration rate slowly increased, while the percentage of infiltrated rainfall scaled up with increasing pumping rates. The predicted recharge of the covering aquitard amounts approximately 14–15 % of the mean annual precipitation. The aquifer recharge takes place from aquitard by seepage. A subsequent simulation of the pumping site’s operation was performed for the 9 years period on the assumption that the pumping rates and the groundwater recharge would be the same as those recorded during the final calibration years. Results show that the post audit measured levels correspond relatively well to the predicted levels and that increasing of the pumping rate causes changes in the water budget in advantage of net groundwater recharge as a consequence of spreading recharge area outside of previous model boundaries.     

济南市有效利用城市雨水回灌岩溶地下水探讨

利用雨水补给地下水已成为城市水资源管理的有效措施.文中以济南市为例探讨了雨水回灌岩溶地下水的途径.济南市具有较好的岩溶水赋存条件,通过人工回灌工程,采用点面结合的回灌方式,利用雨水补给地下水,将城区岩溶水直接补给区的水循环尽可能地恢复到一定的自然状态,最终达到供水保泉的目的.     

A Suitable Tool for Sustainable Groundwater Management

Artificial recharge is used to increase the availability of groundwater storage and reduce saltwater intrusion in coastal aquifers, where pumping and droughts have severely impaired groundwater quality. The implementation of optimal recharge methods requires knowledge of physical, chemical, and biological phenomena involving water and wastewater filtration in the subsoil, together with engineering aspects related to plant design and maintenance operations. This study uses a novel Decision Support System (DSS), which includes soil aquifer treatment (SAT) evaluation, to design an artificial recharge plant. The DSS helps users make strategic decisions on selecting the most appropriate recharge methods and water treatment technologies at specific sites. This will enable the recovery of safe water using managed aquifer recharge (MAR) practices, and result in reduced recharge costs. The DSS was built using an artificial intelligence technique and knowledge-based technology, related to both quantitative and qualitative aspects of water supply for artificial recharge. The DSS software was implemented using rules based on the cumulative experience of wastewater treatment plant engineers and groundwater modeling. Appropriate model flow simulations were performed in porous and fractured coastal aquifers to evaluate the suitability of this technique for enhancing the integrated water resources management approach. Results obtained from the AQUASTRESS integrated project and DRINKADRIA IPA CBC suggest the most effective strategies for wastewater treatments prior to recharge at specific sites.     

Cost-effective Approaches for Sustainable Groundwater Management in Alluvial Aquifer Systems

The consequences of unsustainable use of groundwater are becoming increasingly evident worldwide, particularly in developing nations. Groundwater management is a serious problem in many parts of the world. The prime concern is how to achieve groundwater sustainability. Artificial recharge techniques coupled with water harvesting hold a great promise for groundwater sustainability. The main intent of this paper is to highlight salient cost-effective and easy-to-use methods for augmenting groundwater resources in the alluvial hydrogeologic setting. Based on the intensive field investigation in a groundwater basin of Japan, three low-cost and easy-to-implement recharge techniques are suggested for alluvial aquifer systems, viz., augmentation of river flow, recharge through irrigation/drainage canals, and recharge from paddy fields. The source of recharge water for these recharge techniques is surface water supply. The efficacy of these methods or approaches has been demonstrated. It is emphasized that such cost-effective methods of groundwater recharge are key to sustainable groundwater management in both developing and developed countries. These methods must not be overlooked in the midst of sophisticated and highly expensive methods.     

Natural recharge to sustainable yield from the barind aquifer: a tool in preparing effective management plan of groundwater resources.

This paper presents the results of water balance study and aquifer simulation modeling for preliminary estimation of the recharge rate and sustainable yield for the semi arid Barind Tract region of Bangladesh. The outcomes of the study are likely to be useful for planning purposes. It is found from detailed water balance study for the area that natural recharge rates in the Barind Tract vary widely year to year. It may have resulted from the method used for the calculation. If the considered time interval had been smaller than the monthly rainfall, the results could have been different. Aquifer Simulation Modeling (ASM) for the Barind aquifer is used to estimate long-term sustainable yield of the groundwater considering limiting drawdown from the standpoint of economic pumping cost. In managing a groundwater basin efficiently and effectively, evaluation of the maximum annual groundwater yield of the basin that can be withdrawn and used without producing any undesirable effect is one of the most important issues. In investigating such recharge rate, introduction of certain terms such as sustainable yield and safe yield has been accompanied. Development of this area involves proper utilization of this vast land, which is possible only through ensured irrigation for agriculture. The Government of Bangladesh has a plan to develop irrigation facilities by optimum utilization of available ground and surface water. It is believed that the groundwater table is lowering rapidly and the whole region is in an acute state of deforestation. Indiscriminate groundwater development may accelerate deforestation trend. In this context estimation of actual natural recharge rate to the aquifer and determination of sustainable yield will assist in proper management and planning of environmentally viable abstraction schemes. It is revealed from the study that the sustainable yield of ground water (204 mm/y) is somewhat higher than the long-term annual average recharge (152.7 mm) to the groundwater reservoir. The reason behind this is that the rivers within and around the Barind Tract might have played the role of influent rivers.