区域流场作用下地下水地源热泵系统抽灌模式对地温场的影响

通过建立三维水热耦合数值模型,对区域流场作用下,地下水地源热泵系统运行一个采暖、制冷周期后,不同的抽灌井布局以及交替方式下,地下水地源热泵系统地温场的演变趋势进行模拟分析。结果表明,地下水的天然流速越大,越有利于热量的运移,有助于抽灌井连线垂直于地下水流方向的垂直布局以及地下水流向由抽水井指向回灌井的平行布局下的地温场演化,但不利于地下水流向由回灌井指向抽水井的平行布局下的地温场演化和温度恢复。一般的天然地下水流速条件下,由于含水层储能效应,进行抽灌井季节性交替模式的系统运行效率较高。     

地下水源热泵抽灌井优化布置及参数灵敏度

为了确定地下水源热泵的最佳布井方式,探明含水层温度场变化特征以及水文地质参数灵敏性,以石家庄地下水源热泵适宜区肖家营—东兆通为研究区,基于热储层的地热地质条件和热物性参数,利用FEFLOW软件构建了三维水-热耦合数值模拟模型。在2 000 m³/d的抽灌量下对不同井间距、不同布井模式-含水层温度场变化进行模拟,探讨发生热突破的可能性,并探讨温度场关于热导率、渗透系数、孔隙率等参数的灵敏度。研究结果表明：1)在单抽双灌模式下,方案C(两眼回灌井连线与地下水流向垂直,一眼回灌井位于抽水井正下游,另一眼回灌井位于沿地下水流向45°方向,即两回灌井与抽水井组成等腰直角三角形,抽水井正下游的回灌井为直角顶点)的布井方案对含水层温度场影响最小,为最优方案;2)单抽双灌模式下,抽灌量为2 000 m³/d时,方案C抽灌井间距设置在40～50 m较为合理;3)抽灌过程中,温度场对于渗透系数的改变灵敏度较高,而对孔隙率以及热导率的改变灵敏度较低。     

应用水热运移数值模拟优化地下水源热泵系统抽灌井布局

合理布局抽水井和回灌井是地下水源热泵系统长期有效运行的关键因素。以郑州市郑东新区为例,利用HST3D软件建立水热运移数值模型,优化设计地下水源热泵系统抽灌水井布局,预测地下水源热泵系统长期运行后对含水层的水热影响。结果表明:介质比热容及渗透率分别对含水层温度及水位影响显著,是较敏感的参数。方案3(3个回灌井垂直天然流向分布且位于抽水井下游)为最佳布井方式。抽灌量900,1 200,1 500及2 000m3/d所对应的合理布井间距分别为50,65,70及75m。相应布井方案的水源热泵系统运行20a,对含水层温度场的影响仅限于200m×200m的范围,抽水井温度变化小于1℃。     

水源热泵井群布置方案对地下水流场影响分析

以某地下水源热泵系统工程为例,依据工程场地实际抽水-回灌试验数据,建立研究区地下水流数值模拟模型,分析该地区适宜的井群布置方案,并定量研究不同井群布置方案对地下水流场的影响范围与程度,为确定合理的井群布置方案提供技术支撑。研究表明：对于同一含水层回灌,随着抽水-回灌时间的延长,就有利于抽水-回灌能力及尽量减小对周边地下水开采的影响而言,抽水井、回灌井交叉布置,部分回灌井集中布置的方案较为合理。     

水源热泵应用的细节技术探讨——以北京地区为例

鉴于水源热泵系统中存在一些技术问题未被人们所认识或未引起足够的重视,本文详细阐述了抽灌平衡时地下水动力场及温度场的影响范围估算、抽灌井轮换、水资源保护与热泵效率的关系、抽灌群井布置方式、区域地下水流场对抽灌井布局的影响、浅层地热能储量消耗与热泵的关系、起始运行期选择等七个关于热泵应用的细节技术,为应用水源热泵系统的用户和有关部门提供科学参考,以扬长避短,充分发挥水源热泵系统环保节能的优点。     

地下水地源热泵系统应用对地温场的影响

通过建立地下水地源热泵系统试验场,运行热泵系统,并进行地下水温度连续监测,分析应用地下水地源热泵系统对地温场的影响。抽水井与回灌井之间以及回灌井附近的地下水温度随系统运行明显变化。系统运行后,回灌水体将以不规则边缘的透镜体贮存于含水层中,以回灌井为中心向外围扩展,水温最低或最高点位于含水层中部。粘性土相对隔水层的温度变化幅度、影响范围均小于含水层。由于热量的累积效应,即使是冷热负荷均衡的热泵系统,运行一个采暖、制冷周期后也将在热源井附近的抽、灌水含水层以及相邻的隔水层中形成冷量或热量的小范围聚积。     

场地地下水源热泵系统抽灌实验及数值模拟研究

基于野外实际地下水源热泵系统和长时间抽灌实验,构建场地水文地质概念模型和水热耦合模型,进行场地地下水温度场数值模拟研究。利用场地群井观测数据对所建模型进行验证,诸观测孔各时段的绝对误差均值为0.38℃,平均相对误差率为2.00%,表明模型模拟结果良好。模型经验证后,预测不同抽灌模式下温度场分布,发现季节性交替抽灌结果优于正常抽灌,但均产生热贯通现象,说明现状抽灌井距(30 m)偏小。设计不同抽灌井距情况模拟回灌井对抽水井的影响,得到研究场地合理井距为50 m。进一步研究渗透系数、热弥散度、抽灌水量和回灌水温差对合理井距的影响,发现抽灌水量和回灌水温差的影响最大。     

热屏障井对地下水源热泵换热影响模拟

对于场地受限的地下水源热泵项目,随着系统运行时间的增加易引发热贯通现象进而降低机组运行效率。地下水源热泵设计中,在抽灌水井连线间布设热屏障井可改变地下水流场,降低热量在抽灌井间的运移速度,有利于延长热贯通发生时间并缓解热贯通程度。通过构建地下水换热模型,模拟计算夏季制冷工况条件下36组热泵运行场景,分析了热屏障井的位置,过滤管长度及回灌量对热贯通和含水层温度场的影响规律。结果表明:热屏障井回灌量的增加有利于提升热屏障效果,但提升幅度随回灌量的增加逐渐减弱;最大水位降深值随着热屏障井回灌量的增加呈线性增长;增加热屏障井滤管长度可提升热屏障效果,提升效果随屏障井回灌量的增加逐渐增强。通过模型多周期、长时间模拟计算发现,热屏障井的运行可促使回灌的冷热量集中在回灌井一侧,对于采用冬夏季抽灌井交换运行模式的热泵系统,可充分利用含水层储能,提升机组运行效率。     

热泵耦合含水层储能技术应用研究

本文结合实际工程项目,对对井抽灌模式的热泵耦合地下含水层反季节储能效果进行研究。结果表明对井采灌热泵耦合储能系统能够实现冬灌夏用和夏灌冬用的反季节储能作用,能充分利用浅层地能资源,节约了常规能源。在冷热负荷不平衡的情况下,若系统长期运行可造成采井或者灌井周围一定区域内温度场的降低或者升高,因此在利用对井储能水源热泵空调系统时,要尽量使系统在冷热负荷均衡的工况下运行,以保护地下生态平衡。     

地下水源热泵系统布井方案分析

对于地下水源热泵而言,"热突破"现象普遍存在。但不同的布井方案,即抽、灌井间距和井位的不同,可能引起抽水井的温度变化差异很大,进而影响地温空调系统采能功效。本文结合郑州市儿童医院地温空调实例工程,应用HST3D程序对细颗粒含水层地区1抽2灌模式下不同布井方案进行了分析。结果表明,该区的最佳井间距为50m左右;选择直线型布井,抽、灌井连线平行于天然水力坡度方向,且天然水力坡度由抽水井指向回灌井的方式效果最好。     

地下水可持续开采量与地下水功能评价的关系

针对中国北方地下水评价中偏重资源而对地下水的生态功能和地质环境功能重视不足的问题,立足于流域尺度的地下水循环系统和地下水的自然属性,突出协调综合发挥地下水的资源功能、生态功能和地质环境功能的目标,从地下水可持续开采量与地下水功能的理念基础、评价原则和评价机理3个方面探讨二者的内在关联性,认为它们同源于人与自然和谐的理念,都以流域尺度的地下水循环系统为研究主体,以保护生态与地质环境为目标,彼此相互促进和相互支撑.地下水功能评价是合理确定地下水可持续开采量的充分条件,地下水可持续开采量的合理确定是实现地下水功能评价目标的必要条件;如果二者缺一,则地下水的生态功能或地质环境功能难以得到有针对性的保护.     

Delineation of groundwater potential zones and electrical resistivity studies for groundwater exploration

The electrical resistivity method is widely used in groundwater exploration studies. The method is particularly well suited to carry out groundwater studies in hard-rock terrains. The popular Schlumberger method of electrode configuration was applied in the study area. In all, 112 vertical electrical soundings (VESs) were carried out at different locations in the study area. VES interpretations were used to generate a top-layer contour map and a depth-to-basement map. Finally, a groundwater quality/potential map for the study area was generated using the depth-to-bedrock map, a water-level fluctuation map, and the second-layer thickness. Furthermore, this groundwater potential map was classified into three sectors, i.e. poor, moderate and good zones with respect to the prospects of finding groundwater in the study area. This map has a practical value, as it provides guidance to farmers in selecting favourable well sites, thereby avoiding unnecessary financial losses.     

A graphic expression of salinization and pollution of groundwater The case of Israel's groundwater

 Anthropogenic activities create various contaminated leachate, which can migrate downward from the vadose zone to groundwater, transferring contaminants, including some hazardous ones. When these various sources of contamination influence the groundwater aquifer simultaneously, the effects of contamination are enhanced. The major concern of this study has been to determine whether the shape of a groundwater chlorograph might be the result of such deterministic effects as accumulation of one or more particular processes of groundwater contamination, and how this might relate to specific hydrological situations. This study proposes a classification of groundwater contamination on the basis of properties of the main components of groundwater quality graphs and the corresponding hydrogeological/environmental situation. The study further suggests that contamination of groundwater in any hydrogeological situation (e.g. sea water) may be graphically expressed. A variety of chlorographs and nitrographs, representative of various groundwater aquifers sampled from a number of wells throughout Israel attest to this. The study thus indicates that groundwater quality graphs may be considered as a complementary tool for groundwater quality control and better understanding aquifer situations.     

Patterns in groundwater chemistry resulting from groundwater flow

 Groundwater flow influences hydrochemical patterns because flow reduces mixing by diffusion, carries the chemical imprints of biological and anthropogenic changes in the recharge area, and leaches the aquifer system. Global patterns are mainly dictated by differences in the flux of meteoric water passing through the subsoil. Within individual hydrosomes (water bodies with a specific origin), the following prograde evolution lines (facies sequence) normally develop in the direction of groundwater flow: from strong to no fluctuations in water quality, from polluted to unpolluted, from acidic to basic, from oxic to anoxic–methanogenic, from no to significant base exchange, and from fresh to brackish. This is demonstrated for fresh coastal-dune groundwater in the Netherlands. In this hydrosome, the leaching of calcium carbonate as much as 15 m and of adsorbed marine cations (Na⁺, K⁺, and Mg²⁺) as much as 2500 m in the flow direction is shown to correspond with about 5000 yr of flushing since the beach barrier with dunes developed. Recharge focus areas in the dunes are evidenced by groundwater displaying a lower prograde quality evolution than the surrounding dune groundwater. Artificially recharged Rhine River water in the dunes provides distinct hydrochemical patterns, which display groundwater flow, mixing, and groundwater ages. Received, May 1998 · Revised, August 1998 · Accepted, October 1998     

Isotope hydrology of deep groundwater in Syria: renewable and non-renewable groundwater and paleoclimate impact

The Regional Deep Cretaceous Aquifer (RDCA) is the principal groundwater resource in Syria. Isotope and hydrochemical data have been used to evaluate the geographic zones in terms of renewable and non-renewable groundwater and the inter-relation between current and past recharge. The chemical and isotopic character of groundwater together with radiometric ¹⁴C data reflect the existence of three different groundwater groups: (1) renewable groundwater, in RDCA outcropping areas, in western Syria along the Coastal and Anti-Lebanon mountains. The mean δ¹⁸O value (?7.2 ‰) is similar to modern precipitation with higher ¹⁴C values (up to 60–80 pmc), implying younger groundwater (recent recharge); (2) semi-renewable groundwater, which is located in the unconfined section of the RDCA and parallel to the first zone. The mean δ¹⁸O value (?7.0 ‰) is also similar to modern precipitation with a ¹⁴C range of 15–45 pmc; (3) non-renewable groundwater found in most of the Syrian interior, where the RDCA becomes confined. A considerable depletion in δ¹⁸O (?8.0 ‰) relative to the modern rainfall and low values of ¹⁴C (<15 pmc) suggest that the large masses of deep groundwater are non-renewable and related to an older recharge period. The wide scatter of all data points around the two meteoric lines in the δ¹⁸O-δ²H diagram indicates considerable variation in recharge conditions. There is limited renewable groundwater in the mountain area, and most of the stored deep groundwater in the RDCA is non-renewable, with corrected ¹⁴C ages varying between 10 and 35 Kyr BP.     

石家庄市地下水污染特征及其与超量开采的关系

石家庄市地下水污染以常量组分的含量和指标升高为主要特征，污染源主要来自城市污水，这在我国城市地区地下水污染问题中极具代表性。本在分析污染特征的基础上，对地下水污染与超量开采的关系进行了研究和探讨，揭示了超量开采加剧地下水污染进程的机理，进而提出，超量开采地下水是导致地下水污染的重要诱导因素。     

福建厦门市地下水质量及开发利用建议

地下水质量和污染问题已成为制约城市发展的重要因素.该文对厦门市平原区地下水的有机和无机化学组分进行了系统全面的分析,根据"地下水标准"和"矿泉水标准"对地下水质量进行了综合评价.研究表明:厦门市地下水质量总体一般,可以直接饮用的水占22.9％,经过适当处理可以饮用的水占59.8％,不能饮用的占17.3％.有益人体健康的...     

降水和开采变化对石家庄地下水流场影响强度

为能精确识别降水和开采对石家庄地下水流场影响强度,应用小波变换和相关分析等研究方法,对区域平均地下水位、地下水降落漏斗面积及中心水位与降水和开采变化之间的互动特征进行了研究。结果表明:① 1961—1973年期间,平均地下水位随降水量增大呈幂函数递减趋势;1974—2010年期间,降水量每减小100 mm,漏斗中心水位下降速率增大7.35 m,平均地下水位下降速率增大2.15 m;② 1961—1973年期间,开采量每增加1亿m3,平均地下水位下降0.28 m,漏斗面积扩大11.74 km2,中心水位下降0.52 m,1974年以来累计超采量每增加1亿m3,漏斗面积增幅1.52 km2,中心水位降幅0.18 m;③ 降水量每减小100 mm,降水贡献度减弱3.0%,人类开采影响强度增大2.76%。     

Comparison of GRACE data and groundwater levels for the assessment of groundwater depletion in Jordan

Gravity Recovery and Climate Experiment (GRACE) derived groundwater storage (GWS) data are compared with in-situ groundwater levels from five groundwater basins in Jordan, using newly gridded GRACE GRCTellus land data. It is shown that (1) the time series for GRACE-derived GWS data and in-situ groundwater-level measurements can be correlated, with R ² from 0.55 to 0.74, (2) the correlation can be widely ascribed to the seasonal and trend component, since the detrended and deseasonalized time series show no significant correlation for most cases, implying that anomalous signals that deviate from the trend or seasonal behaviour are overlaid by noise, (3) estimates for water losses in Jordan based on the trend of GRACE data from 2003 to 2013 could be up to four times higher than previously assumed using estimated recharge and abstraction rates, and (4) a significant time-lagged cross correlation of the monthly changes in GRACE-derived groundwater storage and precipitation data was found, suggesting that the conventional method for deriving GWS from GRACE data probably does not account for the typical conditions in the study basins. Furthermore, a new method for deriving plausible specific yields from GRACE data and groundwater levels is demonstrated.