Thermal influence of urban groundwater recharge from stormwater infiltration basins

Groundwater warming below cities has become a major environmental issue; but the effect of distinct local anthropogenic sources of heat on urban groundwater temperature distributions is still poorly documented. Our study addressed the local effect of stormwater infiltration on the thermal regime of urban groundwater by examining differences in water temperature beneath stormwater infiltration basins (SIB) and reference sites fed exclusively by direct infiltration of rainwater at the land surface. Stormwater infiltration dramatically increased the thermal amplitude of groundwater at event and season scales. Temperature variation at the scale of rainfall events reached 3 °C and was controlled by the interaction between runoff amount and difference in temperature between stormwater and groundwater. The annual amplitude of groundwater temperature was on average nine times higher below SIB (range: 0·9–8·6 °C) than at reference sites (range: 0–1·2 °C) and increased with catchment area of SIB. Elevated summer temperature of infiltrating stormwater (up to 21 °C) decreased oxygen solubility and stimulated microbial respiration in the soil and vadose zone, thereby lowering dissolved oxygen (DO) concentration in groundwater. The net effect of infiltration on average groundwater temperature depended upon the seasonal distribution of rainfall: groundwater below large SIB warmed up (+0·4 °C) when rainfall occurred predominantly during warm seasons. The thermal effect of stormwater infiltration strongly attenuated with increasing depth below the groundwater table indicating advective heat transport was restricted to the uppermost layers of groundwater. Moreover, excessive groundwater temperature variation at event and season scales can be attenuated by reducing the size of catchment areas drained by SIB and by promoting source control drainage systems. Copyright © 2009 John Wiley & Sons, Ltd.     

First‐order exchange coefficient coupling for simulating surface water–groundwater interactions: parameter sensitivity and consistency with a physics‐based approach

Distributed hydrologic models capable of simulating fully‐coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first‐order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface‐subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first‐order exchange coefficients at a well‐characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first‐order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first‐order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept‐development simulations to examine real‐world situations where the surface‐subsurface exchange is impaired. While the parameters comprising the first‐order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first‐order exchange coefficient approach can be consistent with a physics‐based framework. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous identification of parameter,initial condition,and boundary condition in groundwater modelling

In this paper, we perform an inverse method to simultaneously estimate aquifer parameters, initial condition, and boundary conditions in groundwater modelling. The parameter estimation is extended to a complete inverse problem that makes the calibrated groundwater flow model more realistic. The adjoint state method, the gradient search method, and the least square error algorithm are combined to build the optimization procedure. Horizontal two‐dimensional groundwater flow in a confined aquifer is exemplified to demonstrate the correlation between unknowns, the contribution of observation, as well as the suitability of applying the inverse method. The correlation analysis shows the connection between storage coefficient and initial condition. Besides, transmissivity and boundary conditions are also highly correlated. More observations at different location and time are necessary to provide sufficient information. A time series of unsteady head is requested for estimation of storage coefficient and initial condition. Observation near boundary is very effective for boundary condition estimation. The observation at pumping well mostly contributes to the estimation of transmissivity. According to all observations, it is possible to identify parameters, initial condition, and boundary condition simultaneously. Furthermore, the results not only illustrate the traditional assumption of known boundary condition but also initial condition, which may cause an incorrect estimation. Copyright © 2009 John Wiley & Sons, Ltd.     

深层地下水SPD人工补给系统

提出了一种新的深层地下水回灌方法———SPD人工补给系统,并通过室内沙槽模拟试验,对该系统和常规的直接井回灌法作了比较。研究表明,利用该系统补给深层地下水,具有回灌水质要求低、补给速度快、补给量多、不易淤堵等特点,是深层地下水人工补给的一条有效的新途径。     

胶东半岛海产养殖地下咸水分布特征及开发利用现状

胶东半岛位于山东省胶莱河以东,区内海岸线全长约1 700km,沿海滩涂面积约500km2。由于该区特殊的自然地理和地质环境条件,赋存有适宜海产养殖的地下咸水。该文依据大量的基础资料,阐述了胶东半岛区内海产养殖地下咸水的分布特征、富水地段资源量及开发利用现状,并针对开发利用中引发的地质环境问题提出了相应的保护建议,对于指导该区海产养殖地下咸水资源科学合理开发利用具有重要的意义。     

官桥断块地下水资源量分析评价

在收集利用前人研究成果的基础上,采用补给量法计算地下水资源量,开采系数法计算地下水可开采资源量,通过调查统计获得地下水开采资源量,最后得到研究区地下水的补给资源量、可开采资源量及剩余资源量,提出地下可持续开发利用建议。     

数值模拟在沂水铁矿区地下水环境影响评价中的应用

地下水数值模拟在矿区地下水环境评价中应用较少,通过对山东沂水铁矿矿区进行水文地质详细勘察,建立了尾矿库及矿区地下水水流及水质数学模型,预测和评价了该矿建设实施过程中对地下水环境可能造成的直接影响和间接危害。结论为矿山建设阶段和运行阶段正常情况下,尾矿区水位水质变化对地下水环境没有明显的影响,非正常情况或者事故状态下,预测污染因子在泄漏点附近一定范围出现超标现象;采矿区矿井排水对当地浅层地下水位影响较大。针对这种影响和危害提出防治措施,为沂水铁矿建设项目选址决策、工程设计和环境管理提供科学依据。     

基于GIS的磐石市地下水环境质量分析

基于ArcGIS建立了磐石市29个监测点的水质信息数据库,采用灰色聚类法进行地下水环境质量评价。利用GIS的空间分析功能,分析地下水中常规组分的空间分布特征,掌握了地下水质量状况。磐石市大部分地区地下水质量良好,达到、级标准。地下水中化学组分的含量从郊区向市区逐渐增加,市区地下水质量为、级标准。地下水已遭受污染,地下水开采降落漏斗区地下水位的持续下降是市区地下水遭受污染的主要诱发因素。     

济南东部大辛河渗漏段地下水示踪试验与分析

2013年以来,济南市为正确处理好保泉和市民饮用优质地下水的关系,组织实施了地表水转换地下水补源系列工程,旨在补源保泉的前提下开采地下水。大辛河地表水转地下水工程是其中重要的组成部分,为了查明大辛河渗漏补源后地下水的补给方向、径流速度等,在大辛河主要渗漏段开展了地下水示踪试验。结果显示:地下水渗漏补源后沿渗漏段—龙奥大厦—济南东区供水奥体加压站—贤文小区一线大体自南向北径流,视径流速度约45m/d,越往两侧流速越缓慢,表明大辛河地表水转地下水工程主要对东郊水源地进行补给,对市区四大泉群补给较弱。示踪试验得出的结论,对大辛河地表水转地下水工程运行具有重要指导作用,对后期管理部门合理规划补源、开采布局具有重要的借鉴意义,促进济南保泉和供水的有机统一。     

水文重力效应改正中一维地下水模拟算法的对比

基于一维地下水渗透方程详细推导其有限差分解算过程,引入不同于显式差分的隐式差分和中心差分格式,对比分析不同差分格式对地下水模拟结果及其相应地下水重力效应的影响,并对其中的层间参数取值和非线性方程的线性化问题进行探讨。结果表明,在日本Isawa扇形地区超导台站,不同层间参数加权公式能够引起最大约0.15 μGal的重力效应差异,影响在1.9%以内;不同差分格式和线性化方法组合形式能够引起最大约0.12 μGal的重力效应差异,影响在1.5%以内。