Fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration.

Understanding the fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration is essential to assess the impact of wastewater effluent on the post treatment requirements of riverbank filtrates. Furthermore, their fate during drinking water treatment can significantly determine the process design. The objective of this study was to characterise bulk organic matter which consists of EfOM and NOM during riverbank filtration using a suite of innovative analytical tools. Wastewater effluent-derived surface water and surface water were used as source waters in experiments with soil columns. Results showed the preferential removal of non-humic substances (i.e. biopolymers) from wastewater effluent-derived surface water. The bulk organic matter characteristics of wastewater effluent-derived surface water and surface water were similar after 5 m soil passage in laboratory column experiment. Humic-like organic matter in surface water and wastewater effluent-derived surface water persisted through the soil passage. More than 50% of total dissolved organic carbon (DOC) removal with significant reduction of dissolved oxygen (DO) was observed in the top 50 cm of the soil columns for both surface water and wastewater effluent-derived surface water. This was due to biodegradation by soil biomass which was determined by adenosine triphosphate (ATP) concentrations and heterotrophic plate counts. High concentrations of ATP in the first few centimeters of infiltration surface reflect the highest microbial activity which correlates with the extent of DOC reduction. Good correlation of DOC removal with DO and biomass development was observed in the soil columns.     

河道内水位变化对上荆江河段岸坡稳定性影响分析

三峡水库蓄水后,上荆江河段来沙急剧减少,河床冲刷下切,局部河段崩岸现象时有发生,影响两岸堤防安全。通常认为水流冲积作用是崩岸的主要控制因素,但已有研究表明,河道内水位变化能改变河岸土体的力学特性及受力条件,进而对崩岸过程产生较大影响。本文将一维非稳定渗流计算及黏性土河岸稳定性计算结合,构建了考虑潜水位变化的岸坡稳定性分析模型,用于计算河道内水位变化时岸坡稳定程度的调整过程。以上荆江河段荆34、公2断面为研究对象,采用该模型计算了2009年实测河道水位过程下相应断面的岸坡稳定安全系数Fs。结果表明:涨水期河岸稳定性较高,洪峰期有所降低,退水期更低;荆34、公2断面最小Fs值分别为0.83、1.39,均发生在退水期,表明前者在该时期会发生崩岸,后者较为稳定,这与实测资料相符。此外还计算了不同河道内水位变化速率下Fs值的变化过程,结果表明:岸坡稳定性在涨水速率增加时增大,在退水速率增加时则减小。因此近期上荆江河段崩岸加剧一定程度上与三峡工程运用后退水过程加快有关。     

岸滤系统对典型污染物的去除机制及影响因素

系统总结了岸滤系统内的污染物,阐明岸滤系统对典型污染物的去除效能,综述岸滤系统对不同种类污染物的去除机制(降解去除有机污染物机制、迁移转化去除无机污染物机制以及自然过滤去除微生物病原体机制)、影响因素及去除技术,展望未来岸滤系统典型污染物的研究方向。     

Identification of River Sections for Domestic Water Supply along the Yangtze River in Jiangsu Province, China

This paper presents major findings from a recent study aiming to systematically determine suitable river sections for local domestic water supply along the Yangtze River in Jiangsu Province, China. On the basis of analysis on the current riverbank utilization and bank stability, accessible and stable river sections in the region were selected. The water quality in these river sections was then studied using a two-dimensional unsteady flow and pollutant transport/transformation model, RBFVM-2D. The model was calibrated and verified against the hydrodynamic data, water quality data and remote sensing data collected from the river. The investigation on the pollution sources along the river identified 56 main pollution point sources. The pollution zones downstream of these point sources are the main threat for the water quality in the river. The model was used to compute the pollution zones. In particular, simulations were conducted to establish the relationship between the extent of the pollution zone and the wastewater discharge rate of the associated point source. These water quality simulation results were combined with the riverbank stability analysis to determine suitable river sections for local domestic water supply.     

Investigating effect of water level variation and surface tension crack on riverbank stability

During high flow season, the rise and fall of river water level could induce riverbank instability and threaten structural safety of flood-protection facilities on floodplains. Through a flume experiment, this paper investigates the influences of three factors (namely, drawdown rate of river stage, initial water elevation, and riverbank slope angle) on riverbank stability due to the fall of river water level. From the laboratory experiments it was observed that tension crack appeared in all riverbank failure cases and all failure patterns were of planar type. Moreover, this paper presents a riverbank stability analysis model that explicitly incorporates the integral effect of all forces acting upon the failure plane and tension crack. The prediction accuracy of the proposed model is examined by using experimental data obtained in this study and field data of the Hotophia Creek in the USA and the Sieve River in Italy. A comparison of model simulation results with and without considering tension crack clearly indicates the importance and necessity of including tension crack for achieving good accuracy in riverbank stability simulations. For practical application of the improved riverbank stability model, two empirical formulas for estimating tension crack location and failure plane angle were examined and modified to enhance their appropriateness in riverbank stability simulation. Finally, the improved model with the modified empirical formulas was verified to show its good prediction in riverbank stability analysis.     

Effects of boundary conditions on the cleaning efficiency of riverbank filtration and artificial groundwater recharge systems regarding bulk parameters and trace pollutants

Drinking water is often produced from surface water by riverbank filtration (RBF) or artificial groundwater recharge (AGR). In this study, an AGR system was exemplarily investigated and results were compared with those of RBF systems, in which the effects of redox milieu, temperature and surface water discharge on the cleaning efficiency were evaluated. Besides bulk parameters such as DOC (dissolved organic carbon), organic trace pollutants including iodinated X-ray contrast media, personal care products, complexing agents, and pharmaceuticals were investigated. At all studied sites, levels of TOC (total organic carbon), DOC, AOX (adsorbable organic halides), SAC (spectral absorption coefficient at 254 nm), and turbidity were reduced significantly. DOC removal was stimulated at higher groundwater temperatures during AGR. Several substances were generally easily removable during both AGR and RBF, regardless of the site, season, discharge or redox regime. For some more refractory substances, however, removal efficiency turned out to be significantly influenced by redox conditions.     

含水率变化对荆江河岸黏性土体力学特性的影响

河岸土体的物理及力学特性是影响崩岸过程的主要因素之一。为研究土体含水率对荆江河岸土体力学特性的影响,于2017年对荆江8个典型崩岸断面进行调查取样,采用实测资料分析、室内土工试验和理论分析相结合的方法,全面地分析了荆江河岸土体组成及力学特性;并结合2016年实测数据定量研究了含水率对荆江河岸黏性土体抗剪强度指标的影响,以及含水率变化对河岸稳定性的影响。结果表明:荆江河岸为上部黏性土、下部非黏性土的二元结构;随含水率的增大,黏聚力先增大后减小,而内摩擦角持续减小;通常黏粒含量越大,其黏聚力峰值越大;含水率与抗剪强度指标存在定量关系;河岸在枯水期稳定性较高,在涨水期较为稳定,在洪水期和退水期稳定性较差。研究结果可供河岸崩岸治理工程技术人员参考。     

A novel SON2‐based similarity index and its application for the rationalization of river water quality monitoring network

In this paper, a novel self‐organizing network (SON) based similarity index and its application for the optimization of sampling locations in an existing river water quality monitoring network (WQMN) is presented. A rationalization of the River Danube WQMN on its stretch through Serbia was performed using the proposed SON²‐based similarity index. A high‐dimensional dataset was used, which is composed of 18 water quality parameters that were collected during the period 2002–2010 at 17 monitoring locations. The SON‐based seasonal classification that divides 12 months into the cold, moderate, and warm seasons was employed, whereas its second application on each seasonal class yielded subclasses that were used to compare the monitoring locations. The obtained SON²‐based similarity index can be utilized for analysing seasonal variations, as well as overall similarities among neighbouring sites. Based on the calculated similarities of locations and characteristics of the River Danube basin a rationalized WQMN, which uses 30% less monitoring sites, has been proposed.     

植物气生根在富营养水治理中的应用——以夹竹桃为例

根据植物气生根能吸收水体中氮、磷养分的特性,首次提出了利用气生根处理富营养水的新方法。以夹竹桃为研究对象,在人工模拟的滨水环境(模拟植物种植于堤岸壁或堤岸上,部分枝叶处于水淹状态的情形)中诱导气生根的生长。结果表明:仅需满足夹竹桃的基本生存条件(土壤、阳光、水和温度),77%的夹竹桃能够适应水淹环境并长出较密集的气生根(平均生根率为38%);夹竹桃对水体TP,TN,NH₃-N,NO₂-N,NO₃-N和浊度NTU的实际去除率分别为27.3%,29.1%,17.1%,20.5%,1.6%和0.7%;同时,栽种在岸堤壁或岸堤上的夹竹桃还具有一定水土保持的作用和景观绿化效果。因此,该方法是一种集富营养水净化、水土保持和景观绿化为一体的新型治理富营养水方法。     

地震多发地区供水管网水质监测点优化布置

针对地震多发地区供水管网系统因地震导致供水管网的局部破损引起的突发性水质污染,提出一种水质监测点优化布置的方法。在定义污染物最短传输时间矩阵与监测矩阵的基础上,构建以各管段因地震受损的概率为权系数、以监测点监测到水质变化所需的总体最短时间为主体的目标函数,在给定的允许监测时间下,通过求解目标函数得出监测点的数量与设定位置。以绵阳市某地区(汶川地震波及地区)供水管网系统为例,运用遗传算法对水质监测点的布置方案进行了优化。     

长江深水航道整治工程生态护岸陆生植被恢复研究

为探究长江深水航道整治工程生态护岸的植被恢复效果,选取立体网状栅格护岸和格状石笼压载植生垫新型生态护岸及传统抛石护岸工程,运用数量生态学研究方法开展工程区陆生植物群落恢复及分布格局调查。研究结果表明:研究区共有植物19种,以草本植物为主,隶属于12科19属;生态护岸工程区植物种类数量高于传统抛石护岸;沿着河岸带横向梯度,立体网状栅格护岸的生物多样性增大,抛石护岸生物多样性变化较大,格状石笼压载植生垫护岸具有较高的生物多样性;生态护岸工程区植物群落的生物量高于传统抛石护岸区,且生物量和沉积物NH⁺₄-N含量显著正相关(p＜0.01);CCA分析表明沉积物中TC和NH⁺₄-N含量对植物群落及物种分布影响较大。综合来看,格状石笼压载植生垫护岸植被恢复效果最好,立体网状栅格护岸次之,传统抛石护岸相对较差;研究区生态护岸的植被恢复还处于动态演替过程,其生态效应有待于长期深入研究。     

大沙河护岸生态效果的数值模拟

利用River2D软件模拟了大连市大沙河多孔栖息单元式生态护岸修建后的水流状况和鱼类栖息地条件。为了选定护岸铺设的位置,以便达到最佳的河流恢复效果,把护岸铺设分为4种方案:方案一维持原貌,不铺设护岸;方案二在整个河段沿岸修建护岸;方案三在需要保护的地方修建河流护底;方案四护岸与护底同时修筑。对比了4种方案下鲤鱼流速适宜指数和河段权重可利用面积,指出了在不同流量下的护岸最佳铺设方式。结果表明利用软件进行数值模拟的方法可以弥补室内实验方法和实地观测方法的不足。     

河岸崩塌机理的理论模式及其计算

河岸滩的崩塌直接危及堤围的安全，作用针对粘性河岸的崩塌问题进行分析和研究，根据河岸整体崩塌情况，提出了一个切实可行的数学计算模型，考虑了河岸可能发生旋转崩塌（窝崩）和平面崩塌两种情况，并将概率分析的方法支用到崩塌的纵向延伸问题上，该模型适用于粘性土河岸及河岸滩的稳定性分析，用于北江社滘段河岸滩的稳定分析计算表明，河槽水位、地下水位、岸滩形态以及河岸滩土质抗冲性的大小等对岸滩的稳定性有不同程度的影响。     

干旱区植物用水对水文条件的响应——以额济纳三角洲胡杨为例

植物用水对水文条件的响应是干旱区生态水文学的重点研究内容。本研究以额济纳三角洲为研究区,选取水文条件不同的典型河岸带植物胡杨(Populus euphratica)为研究对象,同步采集其根茎及可能为植物提供水分的土壤并真空抽提水分,同时采集河水和地下水水样,通过δ18 O分析潜在供水水源(河水、地下水)-土壤水-植物水之间的水分响应关系。研究发现,对于距离过水河道75m(地下水位埋深2.0m)的胡杨,其主要土壤供水层在1.0~2.0m,植物水分有93.7%来自河水;而距离过水主河道2km以外(地下水位埋深3.3m)的胡杨,主要吸收1.4~3.2m的土壤层水分,地下水(由河水补给,但在含水层停留时间较长的河水)对胡杨水分的贡献比例达到80.0%。可见,胡杨用水策略与模式受其距过水河道远近、地下水位深浅影响明显。     

COUPLING EFFECT OF SEEPAGE FLOW AND RIVER FLOW ON THE BANK FAILURE

On the basis of the generalized physical model of the riverbank, the experiments were conducted to study the mechanisms of riverbank failure under the coupling effect of seepage flow and river flow. The experimental setup was specially designed, as well as test point location, parameters and procedures, and the main influencing factors were analyzed affecting riverbank failure based on the failure types, the variations of pore water pressure and soil displacement. The results indicated that the coupling effect has different influences on the bank failure in three aspects: the failure type, the process and the extent. In addition, the river flow played a more important role than the seepage flow in the coupling effect on the bank failure.     

妫水河两侧重要地表水源区生态建设工程设计

妫水河是官厅水库三大入库河流之一,是官厅水库的重要水源之一。由于常年污染,上游水库补水不足,水质较差。根据妫水河水源保护区的环境状况和存在问题,对妫水河地表水源区开展生态治理工程,以实现妫水河“水清、岸绿、游畅”的生态环境目的。     

NUMERICAL STUDY ON THE PURIFICATION PERFORMANCE OF RIVERBANK

During the rain time, the runoff infiltrates into the riverbank through the collecting gutter and slope surface. The city runoff is generally polluted by organic, oil, heavy metal particulates, etc. The pollutants moving with the water through the riverbank experience advection, dispersion, diffusion, adsorption, biochemical reaction and plant uptaking processes. In this article, a mathematical model was developed to simulate the performance of pollutant removal of the riverbank. The model took those main mechanisms into account. The modified Richards equation was used in simulating flow field. The mass balance law was employed in deriving the equation for pollutant transport, where the diffusion and dispersion were described with the Fick-type law, the adsorption was macroscopically expressed as form isotherm, and the bio-chemical degradation process was assumed to follow the Monod kinetics. The NH3-N and TP were considered in the present model. The mathematical model was descritized with a finite element numerical model, which was applied to two types of model riverbanks. In the model test, the hydraulic loading was assumed to have the intermittent pattern simulating the storm runoff of certain return period, and the values of the rainfall runoff and concentrations of the NH3-N and TP were taken from the model test. The computed overall removal rates for the NH3-N and TP in 6 cases are in the range of 88%-98%, 87%-97%, respectively. The differences between the computed and tested overall removal rates for the NH3-N and TP are less than 5%. The time-varying oscillation pattern of the concentrations of the NH3-N and TP were rationally simulated, which shows that the model presented in this article can be used to assess the purification performance of the riverbank constructed with sand or soil.     

山丘区土地整理探讨

针对山丘区特殊的地形、水资源情况,对灌溉水源选择、渠道最优断面形式确定、河堤附近农田排水进行了初步探讨。结果表明,山丘区灌溉水源以降雨形成的两岸冲沟和蓄水池为水源较好;渠道断面宜采用宽深比在0.7-0.8之间的梯形或U形断面;河堤附近田块排水可在河堤与两岸冲沟相交处,河堤呈"八"字形沿冲沟上游加长至河堤堤顶等高程处,同时将河堤两旁的河滩地整理成田面坡度靠近河堤附近高,排水沟傍山布置并与两岸冲沟相连,河堤附近田块灌溉以蓄水池蓄水灌溉替代渠道从河道取水灌溉,保证河堤完整性。     

应用底栖无脊椎动物完整性指数评价漓江水系健康状况

为了通过漓江底栖无脊椎动物状况建立适合漓江的生物完整性指数,进而评价漓江流域内水质健康状况,于2008年3月调查了漓江水系17个参照点和14个监测点的水化学与底栖无脊椎动物指标,水质化学指标检测结果显示,参照点的TP、TN、NH3-N和COD浓度一般低于监测点。通过对46个候选生物参数的计算和逐步分析,确定了构成底栖动物完整性B-IBI指数的4个生物参数:总分类单元数、EPT分类单元数、扁蜉占蜉蝣总数的百分比和优势单元数量百分比,初步确立了B-IBI健康评价标准,即B-IBI≥21为健康;B-IBI21为不健康。评价结果表明:漓江上游及各支流健康状况较好,大部分为健康;中下游干流健康状况较差,大多为不健康。     

广州城市河流形态对河流自净能力的影响

构建了包括河道分维数、河道断面形态、河岸基质、河岸带宽度、河岸带植被盖度、河床底质状况、河床栖境复杂性共7项指标的城市河流形态评价体系,并以乌涌广州市开发区段为研究对象,通过定期水质监测研究河流形态对河流自净能力的影响。结果表明,该评价体系能够反映研究河段的形态差异;不同形态河段水体BOD5降解系数及多项水质指标沿程降解率均有显著性差异;河流形态评价得分较高的河段水体自净能力也较强;河流形态与NH3-N、SS、DO和浊度的降解存在相关性,是影响河流自净能力的重要因素。