Influent flow control to increase the pollution load treated during rainy periods

The European Directive of May 1991 concerning urban wastewater treatment points out that sewerage systems must be designed to limit the pollution of receiving watercourses by stormwater discharges. As for the system management, the French Decree of 22 December 1995 states that flows or pollution loads exceeding the reference capacity of the treatment plant may be temporarily admitted. This is especially interesting in the case of separate wastewater sewerage, as inappropriate connections of runoff water and rainfall induced infiltration cause hydraulic overloads in such networks. An automated influent flow control has been implemented on a 8000 population equivalent plant to admit a maximum of twice the dry weather peak flow: the clarifier is then dynamically managed so that neither sludge loss nor degradation through anoxic conditions may occur. A yearly simulation of such a strategy on a smaller treatment plant shows a very significant reduction (90%) of the volume discharged during rainy periods. It can therefore be concluded that a plant with additional hydraulic capacity and good sludge quality can play a significant role in limiting the stormwater discharges from separate sewerage systems. However this operational benefit depends on the inflow composition in the sewerage system (wastewaters, rain and infiltration waters).     

Problems and challenges of urban water resources development

A simulation model, WASHMO, is used to illustrate how urbanization influenced flood peaks and volumes for the 1:50 year event in the Palmiet River. The impact of urban stormwater on the channel and the water quality of urban rivers are discussed. Suggestions are made for better urban stormwater control.     

Analysis of scenarios for wastewater and urban drainage systems in Brazil based on an integrated modeling approach.

Brazil is currently facing widespread problems in the urban environment associated with inadequate wastewater and urban drainage systems, particularly for low-income communities. These problems are promoted by the rapid and often unplanned urbanization process in developing cities and are compounded by a lack of funding, absence of planning, ineffective institutional arrangements, and inappropriate policies to provide the framework for integrated wastewater and stormwater management. Because planning for the provision of wastewater and urban drainage systems is a complex task, an integrated-modeling approach is proposed to provide a practical methodology for sanitation and urban drainage planning in Brazilian cities. In the model development, as well as technical aspects, other aspects related to institutional, financial, socio-economic, environmental and public health issues were also taken into account.     

A 2000-year spatiotemporal pattern and relationship between cities and floods in the Yangtze River Basin,China

The Yangtze River is one of the most important rivers in China, and its basin is the most populous urban area in China. The relationship between cities and floods in the Yangtze River Basin is of significance. In our analysis of 4,511 historical county-level cities and 37,512 historical flood disasters, we used ARCGIS to conduct spatial analyses, including kernel density analysis, coldspot and hotspot analysis, and center of gravity analysis, to reveal the relationship between cities, population, and floods in the Yangtze River Basin in the past 2000 years. The results indicate that three relatively stable, dense urban areas are the Chengdu Plain; the border of the Anhui, Zhejiang, Jiangsu Provinces and surrounding areas; and the central Guizhou Province and southwestern part of Hubei Province. The hotspot areas of floods were the main tributaries and lakes of the Yangtze River, whereas the coldspot areas were the Chengdu Plain and the surrounding areas. More importantly, cities are not far from flood regions, and this will cause serious flooding. Due to location advantages, cities tend to be close to rivers, lakes, and other water systems. This research provides historical details of urban development and ecological environment protection in the Yangtze River Basin in China.     

Integrated urban stormwater management: Evolution and multidisciplinary perspective

This paper proposes an introductory review of the historical evolution of urban stormwater management, as well as of current trends, challenges, and changes of paradigm. It reminds us first that most of the existing urban stormwater infrastructures in developed cities are based on the modern urban sewer systems developed in the second half of the 19^th century in Europe. They have been built and for decades managed almost solely by urban sanitation and water specialists, relatively independently of other technical services and, more generally, of other stakeholders in cities. They contributed significantly to public health and fast conveyance of stormwater outside the cities. However, at the turn of the 1970s, it became evident with increasing urbanisation that they also had drawbacks: artificialisation of soils, reduction of aquifer recharge, pollution of surface water and ecological impacts, etc. The paper indicates how new concepts and paradigms thereafter emerged to manage stormwater by means of more sustainable and integrated approaches, aiming to solve the problems engendered by the previous approaches. This integration embraces more and more disciplines and issues, far beyond the traditional field of urban water engineers and specialists. The paper attempts to explain the need for this evolution, making urban stormwater management more much complex, dealing and interacting with ecology, biodiversity, bioinspiration, architecture, landscape and water values, citizens’ well-being, history, culture, and socio-economic aspects.     

分流制雨水与合流制溢流水质的比较

排水管道系统是城市基础设施的重要组成部分,它的完善程度影响着整个污水处理和水污染控制系统的运行状况和效率.而排水体制的选择需要结合当地的地形、降雨类型、管理情况等实际情况出发,综合分析确定.从实测数据和理论计算两个方面对分流制雨水和合流制溢流的浓度和污染负荷量进行了初步的比较,简要地讨论了两种排水系统的适用条件,为排水体制的选择和城市水污染控制的战略决策提供参考.     

珠江流域片水资源利用和保护

珠江流域片包括珠江水系、韩江、海南诸河流域、西南境内国际河流，蕴含丰富的水利、不能资源，近期水质受到在右城市点源污染严重。目前，全片已建立蓄水、引水、供水工程体系，基本满足农业、工业、生活用水，但部分地区水资源短缺，供水工程老化、不够完善，水质污染问题严重，要保证珠江流域不资源的持续发展，就要重视水资源长远规划及大中小水源工程管理建设，对水资源进行优化配置，开辟新水源，节约农业、工业、生活用水，依     

常州市主城区畅流活水方案模拟比选及现场试验研究

为了改善常州市主城区水环境,通过数值模拟计算与现场试验相结合的方法,开展畅流活水水环境提升方案研究。利用优质丰富的长江水作为引水水源,通过魏村枢纽和澡港水利枢纽引水,围绕新建工程大运河西枢纽及与4座活动堰工程的调度组合,设置了5组模拟方案,通过水动力数学模型,模拟各方案下城区内部河道流量分配情况,并结合现场试验论证了推荐活水方案的效果。结果表明：推荐方案形成了3级水位差、水位调控精准、流量分配合理的畅流活水格局,河网水环境改善显著,同时大部分水质指标在引水结束后16 d内均仍处于较好的状态,但部分河道的水质反弹明显。通过数学模型开展水动力调控是改善平原河网城市水环境的有效手段;但需要强化日常监测,根据水质变化情况合理确定活水周期,同时对部分水质异常点位开展污染源解析工作,保障河网水环境的长效久治。     

Utilising integrated urban water management to assess the viability of decentralised water solutions

Cities worldwide are challenged by a number of urban water issues associated with climate change, population growth and the associated water scarcity, wastewater flows and stormwater run-off. To address these problems decentralised solutions are increasingly being considered by water authorities, and integrated urban water management (IUWM) has emerged as a potential solution to most of these urban water challenges, and as the key to providing solutions incorporating decentralised concepts at a city wide scale. To incorporate decentralised options, there is a need to understand their performance and their impact on a city's total water cycle under alternative water and land management options. This includes changes to flow, nutrient and sediment regimes, energy use, greenhouse gas emissions, and the impacts on rivers, aquifers and estuaries. Application of the IUWM approach to large cities demands revisiting the fundamental role of water system design in sustainable city development. This paper uses the extended urban metabolism model (EUMM) to expand a logical definition for the aims of IUWM, and discusses the role of decentralised systems in IUWM and how IUWM principles can be incorporated into urban water planning.     

优化方法分析中新天津生态城雨水利用综合效益

城市水资源的短缺使得雨水利用的必要性进一步增加,如何从城市水资源系统整体出发,定量评价雨水利用所带来的综合效益以及对其他系统的影响也越来越受到重视。通过运用水资源多目标优化配置方法并考虑分质供水后的情况,对中新天津生态城雨水利用的综合效益进行评价,结果表明,雨水利用不仅节约了其他水资源消耗,降低了供水成本,而且旱季和雨季污染物排放量均有明显减少,约减少17%。降雨频率、土地利用差异对雨水利用量及其利用效益有着明显的影响。     

阜阳市主要河流水质评价及污染源解析

针对阜阳市地表水近年来污染依然严重、污染源组成及来源不明等问题,以阜阳市境内颍河、泉河、茨淮新河、淮河、黑茨河、谷河共6条河流为研究对象,按丰水期和枯水期分别采集34个水样,通过综合水质标识指数法及因子分析法对研究区进行水质评价和污染源解析。结果表明:①阜阳市地表河流污染物以COD_(Cr)、TN、TP为主,水体富营养化风险较大。②不同河流综合水质评价显示,颍河河水总体呈Ⅳ类水,从上游至下游呈好转趋势;茨淮新河饮用水保护区水质较好,但上游黑茨河污染较重,主要与支流雨污直排有关。③因子分析显示,颍河和泉河污染物来源主要为农业面源污染、生活污水、工业污水排放等。研究成果可为阜阳市控源截污和水环境安全提供科学依据。     

Water quality assessment of rivers in Mongolia.

A study was made on the water quality of the rivers in Mongolia over the years 1949-1990 for the three river basins in the country. In most of the 72 monitoring stations, the water quality is governed by geological and hydrological characteristics; bicarbonate and calcium are the most abundant major ions. No significant trends were observed between river discharges and total dissolved solids contents. The sediment yields (expressed in the run-off of total suspended solids, TSS) were always low, viz. between 0.02 and 20 x 10(3) kg TSS/km2 yr. In general, the rivers in Mongolia showed low pollution levels for organic pollution, phosphorus, nitrogen, etc., and no time trends were observed in this respect. This does not hold, however, for the northern Tul River, where especially high BOD and ammonium values were found. This can probably be ascribed to the presence of industries and larger cities, as well as agricultural practices. The rivers in Mongolia can generally be classified as "clean" or "of acceptable quality". In contrast, the Tuul River was shown to be "moderately polluted", with a deteriorating trend in water quality over recent years.     

QUAL2E模型在呼和浩特市水质模拟中的应用

呼和浩特市的地表水系由黄河干流和支流组成,以支流为主,整个地表水系统呈树枝状分布,水质污染严重。建立了呼和浩特市的河流水质模型,选用BOD5,CODMn作为模拟污染指标,给出模型关键参数的确定方法,应用QUAL2E模型进行河流水质模拟分析,检验QUAL2E模型参数。模拟结果表明,模型合理有效,能很好地描述河流的水质状况,可进一步为水环境规划提供有利工具和科学的参数依据。     

长江水资源保护与可持续发展

目前长江水质总体尚好 ,但是局部水域污染严重 ,以有机物污染为主。当前长江流域水污染的主要特点为 :江河水污染特别是干流近岸水域污染未能得到遏制 ;流域内地表水体富营养化严重 ;白色污染未得到有效控制 ;非点源污染问题不应忽视。从长江流域可持续发展角度分别对城市发展、工业发展、农业和农村发展的水环境问题识别其影响 ,提出实现长江水资源可持续利用的关键是统一进行流域的整体环境保护规划 ,重点处理各个区域间的矛盾 ,尽最大可能满足各个区域对环保和供水等的要求 ,同时要进行水资源管理体制、水资源投资体制、水价政策的改革 ,并根据长江流域的具体情况制定 2 1世纪的长江水战略 ,以促进流域经济的可持续发展。     

Loading and lake circulation structures recurrent patterns of water quality on the Toronto – Mississauga waterfront of Lake Ontario

Urban centers line western Lake Ontario where urban rivers, wastewater treatment plants and stormwater load nutrients, major ions and suspended solids to the nearshore. In 2018, nearshore water quality and associated physical conditions bordering the cities of Toronto and Mississauga were assessed as a benchmark for future effects of urban growth and municipal infrastructure projects to improve water quality. Conductivity and UV-fluorescence were used as water quality surrogates and mapped over blocks of shoreline stratified by distance offshore. Patterns in UV-fluorescence aligned with loading points, and generally higher levels near the shoreline, were correlated with concentrations of nutrients, major ions and suspended solids. Water quality was more land-impacted over the shoreline from the Credit River to Humber Bay contrasting with the more lake-like conditions from Toronto Eastern Beaches to the Rouge River. Within Toronto Harbour, cross-harbour gradients in water quality varied with weather-related changes in river and storm water loading. Mixing areas at wastewater treatment plant outfalls and tributary mouths, frequently shaped by alongshore lake circulation, resulted in a mosaic of water quality over the shoreline. Area-wide elevation of chloride and conductivity, and poorer water quality in late spring, was linked to heightened river discharge. Thermal stratification affected how discharges were distributed in the water column, but measurements at the lake surface reflected the strongest overall land-effects on water quality. The patterns of temporal-spatial variability identified within geographically-defined areas of shoreline can be used as past footprints in future monitoring to detect change.     

城市河流综合治理开发与效益分析——以临沂市小涑河为例

城市河流综合治理对滨水城市的社会经济发展和生态环境建设具有重要意义。以临沂市小涑河为例,论述了城市河流综合治理开发可采取的措施,并通过建立评价指标来分析治理后所带来的社会、经济和生态环境效益。结果显示,治理后的小涑河,基本实现了"蓄一河清泉水、建一条经济带、成一道景观线"的社会、经济和生态发展目标。为同类城市河流的综合治理开发提供了理论和实践经验。     

天津滞缓流型城市河网水质时空分布特征

针对天津城市河网滞缓流特点突出、水质变化与天然河流不同的特征,以海河、津河、卫津河、外环河4条重点河道为研究对象,应用聚类分析、因子分析、多元线性回归分析等多元统计分析方法对11个重点河道断面2008年和2009年39周的水质监测指标进行了分析。结果表明:河道断面水质在时间和空间上具有一定的分布特征,时间上,各断面5—8月水质较其他时间更差,氨氮、总磷超标严重;空间上,呈现出从海河到津河、卫津河再到外环河水质逐步下降的特征;海河、津河、卫津河等河道氮磷类汇入是主要污染源,外环河则以有机物污染汇入为主要污染源。     

深圳城市两级排水系统设计暴雨重现期的衔接关系

城市内涝防治采用市政排水与水利排涝两级排涝模式,针对城市两级排水系统标准无法衔接的问题,以深 圳市大空港区为例,考虑城市两级排水系统可能遭遇的两类衔接风险,通过构建雨量结构关系分别得到以短历时 暴雨为主和以长历时暴雨为主的设计暴雨重现期衔接关系。同时利用芝加哥雨型和珠江三角洲雨型分别推求市 政排水与水利排涝设计暴雨过程,以探讨城市两级排水系统设计暴雨雨峰之间的衔接关系。最终通过 Spearman 相关系数评估截留河流域各条支流的衔接关系与地理参数之间的相关性。结果表明,水利排涝与市政排水设计 暴雨重现期的衔接关系受降雨强度和降雨历时共同作用,且设计暴雨雨峰衔接关系存在地区差异性。以德丰围 涌为例,在市政排水设计暴雨重现期为 X 年一遇时,水利排涝设计暴雨重现期应至少设计为（2~3）X 年一遇才能 实现城市两级排水系统的衔接。     

长江经济带内陆节点城市生态系统状态评价研究——以长江中游城市带为例

在长江经济带战略的实施中,内陆城市开放发展对城市生态环境造成了较大的压力。利用"压力-状态-响应"模型(PSR),对长江中游城市带的10座中心城市生态系统压力、状态和响应进行了综合评价。评价结果表明:1工业污水、废气和固体废弃物排放是城市生态系统产生压力的主要来源;2长江中游城市带中大部分城市生态系统健康状态处于良好以下水平;3加强污染治理项目投资、提高城市森林覆盖率和绿地面积对减缓城市生态系统压力具有较大作用。     

三峡库区水环境问题及保护对策

采用单因子指数法对三峡库区进行地表水水质评价,结果表明:三峡库区(长江、嘉陵江、乌江)水质总体保持Ⅱ~Ⅲ类标准,无明显恶化趋势;但次级河流污染严重,Ⅰ、Ⅱ、Ⅲ类水质的断面数仅占48%,水质较差。对研究区水环境存在的主要问题及形成原因作了剖析,指出工业污水、固体废物、水土流失、生活垃圾、农业非点源污染是造成近年来水环境污染加重的主要原因,市政水处理设施严重滞后也是造成库区水环境质量改善缓慢的主要原因。提出了三峡库区可持续水环境保护的对策。