Investigation of groundwater residence times during bank filtration in Berlin: a multi‐tracer approach     

Gudrun Massmann  Jürgen Sültenfuß  Uwe Dünnbier  Andrea Knappe  Thomas Taute  Asaf Pekdeger 《水文研究》2008,22(6):788-801

Berlin relies on induced bank filtration from a broad‐scale, lake‐type surface water system. Because the surface water contains treated sewage, wastewater residues are present in surface water and groundwater. Multiple environmental tracers, including tritium and helium isotopes (³H, ³He, ⁴He), stable isotopes (δ¹⁸O and δ²H) and a number of persistent sewage indicators, such as chloride, boron and a selection of pharmaceutical residues (phenazone‐type analgesics and their metabolites, carbamazepine and anthropogenic gadolinium, Gd_excess), were used to estimate travel times from the surface water to individual production and observation wells at two sites. The study revealed a strong vertical age stratification throughout the upper aquifer, with travel times varying from a few months to several decades in greater depth. Whereas the shallow bank filtrate is characterized by the reflection of the time‐variant tracer input concentrations and young ³H/³He ages, the deeper, older bank filtrate displays no tracer seasonality, ³H/³He ages of a few years to decades and strongly deviating concentrations of several pharmaceutical residues, reflecting concentrations of the source surface water over time. The phenazone‐type pharmaceuticals persist in the aquatic environments for decades. Bank filtration in Berlin is only possible at the sandy lakeshores. In greater water depth, impermeable lacustrine sapropels inhibit infiltration. The young bank filtrate originates from the nearest shore, whereas the older bank filtrate infiltrates at more distant shores. This paper illustrates the importance of using multiple tracer methods, capable of resolving a broad range of residence times, to gain a comprehensive understanding of time‐scales and infiltration characteristics in a bank filtration system. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

黄河银川平原段河岸摆动速率变化及其影响因素(英文)     

王随继  李玲  程维明 《地理学报(英文版)》2014,(4)

It is important to examine the lateral shift rate variation of river banks in different periods. One of the challenges in this regard is how to obtain the shift rate of river banks, as gauging stations are deficient for the study of river reaches. The present study selected the Yinchuan Plain reach of the Yellow River with a length of 196 km as a case study, and searched each point of intersection of 153 cross-sections(interval between two adjacent cross-sections was 1.3 km) and river banks in 1975, 1990, 2010 and 2011, which were plotted according to remote sensing images in those years. Then the shift rates for the points of intersection during 1975–1990, 1990–2010 and 2010–2011 were calculated, as well as the average shift rates for different sections and different periods. The results show that the left bank of the river reach shifts mostly to the right, with the average shift rates being 36.5 m/a, 27.8 m/a and 61.5 m/a in the three periods, respectively. Contemporarily, the right bank shifts mostly to the right in the first period, while it shifts to the left in the second and third periods, with the average shift rates being 31.7 m/a, 23.1 m/a and 50.8 m/a in the three periods, respectively. The average shift rates for the left and right banks during the period 1975–2011 are 22.3 m/a and 14.8 m/a, respectively. The bank shift rates for sections A, B and C are different. The shift rate ratio of the left bank in the three sections is 1:7.6:4.6 for shift to the left and 1:1.7:3.8 for shift to the right, while that of the right bank is 1:1.8:1.2 for shift to the left and 1:5.6:17.7 for shift to the right during the period 1975–2011. Obviously, the average shift rate is the least in section A, while it is maximum in section B for shift to the left and in section C for shift to the right. The temporal variation of the shift rate is influenced by human activities, while the spatial variation is controlled by the local difference in bank materials.  相似文献   

考虑河流地貌演化因素的清江隔河岩库区岸坡稳定性预测     

李景富  ;常宏  ;谭建民 《华南地质与矿产》2014,(2):162-168

根据清江中下游河流地貌演化与岸坡稳定性的响应关系,将河流地貌演化因子作为岸坡稳定性评价指标,采用层次分析与信息量评价模型相结合的方法,通过地理信息系统实现了清江隔河岩库区的岸坡稳定性定量预测,其预测结果与现实情况比较吻合。研究表明该方法是一种行之有效的岸坡稳定性预测方法,以及河流地貌演化对岸坡稳定性预测具有显著作用。  相似文献   

分层岸滩侧蚀坍塌过程及其水动力响应模拟          下载免费PDF全文

假冬冬  黑鹏飞  邵学军  张幸农 《水科学进展》2014,25(1):83-89

非均质岸滩广泛分布于冲积河流中,其侧蚀过程沿垂向具有分层特点。基于全三维水沙模型及河岸侧蚀坍塌力学模式,提出动态网格跟踪技术,构建了非均质岸滩侧蚀沿垂向差异的三维动力学模拟方法。以连续弯道概化水槽为例,模拟分析了非均质河岸侧蚀过程中三维水流结构的响应特征。研究结果表明:坡脚冲刷后,底部主流向凹岸偏移,在已有弯道环流的基础上,于坡脚处出现一反向次生流;上部粘性土层坍塌后,崩塌土体堆积于坡脚处,上部主流明显左偏,下部次生流消失;随着坡脚堆积体的冲刷搬运,下部主流进一步向凹岸偏移;如此循环,主流不断向凹岸偏移,致使岸坡持续崩退、河道摆动。  相似文献   

崩塌体水力输移与塌岸淤床交互影响试验          下载免费PDF全文

余明辉  郭晓 《水科学进展》2014,25(5):677-683

以二元结构河岸崩塌模式为研究背景,在弯道水槽中展开系列试验,研究凹岸坡脚处成型崩塌体在水力作用下输移过程及其对岸坡稳定性与河床冲淤的交互影响。试验成果表明,崩塌体经水力分解破碎呈块状、片状或颗粒状起动,部分随水流带至凸岸或下游,堆积在坡脚附近的崩塌体残留量随水力作用大小及土体特性不同而变化。崩塌体临水面周围尤其上下游端水流紊动强烈易形成较大剪切力区,临坡面上下游端附近剪切力较无崩塌体时减小;崩塌体体积越大,对剪切力区特征的改变也越明显。崩塌体的存在虽不能制止附近岸坡的再次崩塌,但可能抑制崩岸发展及附近河床淤积的程度,崩塌体的粘性或体积越大,这种抑制作用越显著;相同崩塌体抑制附近河床淤积的程度较抑制岸坡崩塌的程度大。  相似文献   

渤海西岸全新世气候演化与海陆变迁     

李凤林  阎玉忠  商志文 《江苏地质》2014,38(2):173-186

应用第四纪地质学和海相生物等化石数量统计,以天津马棚口海岸带BQ1孔化石鉴定与统计结果,对古气候、古事件进行对比研究。通过岩芯编录,在岩性层中划分出4个海相层、5个过渡层、9个海面波动。结合研究区广泛分布的贝壳堤和牡蛎礁,利用其大量的测年资料,重现了6道海岸线;根据海相化石个体统计数,画出全新世气候演化曲线,与孢粉和物候所画的古气候演化曲线大体一致。研究历代海陆变迁,必然涉及到历史上长期争论不休的西汉大海侵等问题,谭其骧（1965）圈定的大海侵范围、海岸线分布以及考古结果几乎都能联系在一起,因此,大海侵之谜终于尘埃落定。考古界对河北平原自东汉—金的空白也有了初步答案,同时,发现中国朝代兴衰与气候冷暖有明显的对应,从而建立了气候分期。  相似文献   

Resting Stages of Plankton in Recent North Adriatic Sediments   总被引：6，自引：0，他引：6  

Fernando Rubino  Genuario Belmonte  Anna M. Miglietta  Sebastiano Geraci  & Ferdinando Boero 《Marine Ecology》2000,21(3-4):263-284

Abstract. Plankton-derived resting stages were found in 26 sediment cores collected in the North Adriatic Sea; 46 morphotypes were identified, 38 were attributed to taxa according to their morphology and, in some hatching cases, also according to the morphology of the derived active forms. Six species of Dinophyta were recorded for the first time from the North Adriatic Sea. Each morphotype was described in detail. Twenty-nine resting stages were Dinophyta; one was a Chrysophyta; two were Tintinnina; and six were metazoans. At every site Dinophyta cysts were more abundant than Metazoa cysts. Cyst bank densities were variable, with empty forms generally more abundant than full ones; cyst concentrations were highest at the mouth of the Po River delta.  相似文献   

杭州湾北岸临港新片区岸段潮滩沉积特征     

章馨谣  戴志军  魏稳  陈云 《海洋通报》2022,(5)

近年来,海洋生态系统生态修复成效评估研究日益受到关注。本文梳理了国内外在红树林、珊瑚礁、海草床、盐沼湿地等四类典型海洋生态系统生态修复成效评估指标和评估方法方面的研究进展。结果表明,典型海洋生态系统在进行生态修复成效评估时,基于修复目标和修复方法,评估指标选取虽各有侧重,但主要包括生物和生境状况两个方面。多数生态修复项目的监测、评估都是在短期内进行的,缺乏长期、连续性监测,社会和经济相关指标的研究还相对较为缺乏。成效评估方法目前没有比较清晰、全面的分类。实际应用的评估方法较为单一,对海洋生态系统服务价值揭示不够全面。  相似文献   

Streambank dewatering for increased stability     

F. Douglas Shields Jr  Andrew Simon  Seth M. Dabney 《水文研究》2009,23(11):1537-1547

Streambank erosion is often the dominant source of sediment leaving modified watersheds. Mass failure of high, steep banks is one of the most serious forms of streambank erosion. The risk of a given bank experiencing mass failure is a function of bank height, angle, and soil strength, which is governed by soil moisture. Two methods for bank dewatering were tested in adjacent sections of streambank bordering a deeply incised channel in northern Mississippi: a low‐cost pump system and subsurface horizontal drains. Pore water pressures (both positive and negative pressures, or matric suction) were continuously monitored for 2 years at the pumped site, at an adjacent untreated control section, and for 1 year at the site stabilized with horizontal drains. Resulting data were used to calculate a time series of the factor of safety using a computer model. Over the course of two wet seasons, average bank retreats for the control and pumped plots were 0·43 and 0·21 m, respectively. More limited monitoring revealed that the site with passive drains retreated about 0·23 m. At the pumped site pore water pressure was 3–4 kPa lower than at the control site during the most critical periods. Accordingly, computed factors of safety were above the failure threshold at the pumped site, but fell below unity at the control site on 11 occasions over the period of observation. Similarly, the drained site displayed generally lower pore water pressure and higher safety factors except for two events when drains were evidently overwhelmed with the volume of local surface and subsurface flows. These results suggest, but do not prove, that bank dewatering promoted lower rates of bank retreat and higher levels of stability since the three sites had slight differences in soils, geometry and boundary conditions. Initial cost of the dewatering treatments were significantly less than orthodox bank stabilization measures, but operation and maintenance requirements may be greater. Published in 2009 by John Wiley & Sons, Ltd.  相似文献   

Modelling the advance–retreat cycle of a tidewater glacier with simple sediment dynamics     

J. Oerlemans  F.M. Nick 《Global and Planetary Change》2006,50(3-4):148-160

We present a simple coupled glacier-sediment model to simulate the evolution of a tidewater glacier. The model is based on a consideration of the total mass budget of a glacier, whereas ice mechanics are fully parameterized. The calving rate at the glacier terminus is assumed to be proportional to the water depth. We show that the formation of a morainic shoal has a profound influence on the response of a tidewater glacier to climatic forcing. For a slow periodic forcing of the equilibrium-line altitude, the model glacier advances steadily into the estuary, builds up a submarine terminal moraine, and then retreats rapidly when a critical point is hit. For a slowly increasing equilibrium-line altitude, at a rate as low as 1 m per 5 years, we find terminus retreat rates of up to 10 km in 50 years. Our model suggests that, although the response of tidewater glaciers to external forcing is strongly nonlinear, the onset of retreat is controlled by climate change.  相似文献