Orthophosphate Concentrations in the River Thames

Observed concentrations of orthophosphate in the River Thames, from its source to its tidal limit, exceed 0.1 mg P/1 for most of its length; reasons for annual and seasonal variations are explained. By using data routinely collected by the Environment Agency throughout the Thames catchment, the orthophosphate load in the river, derived from agricultural sources and sewage-treatment works, is estimated.
A water quality model, TOMCAT, has been adapted to simulate observed data and used to estimate river concentrations if orthophosphate loads from sewage-treatment works are reduced.     

Design of the Thames Water Ring Main

The Thames Water ring main is a 2.5 m dia. tunnel approximately 50 m below ground and 80 km long, which conveys potable water from major treatment works, located west of London, into central London. The scheme was constructed during the late 1980s and early 1990s.
In 1985, to meet increasing water demand, a gravityfed system of deep tunnels was devised by Thames Water Utilities Ltd; this involved a full ground investigation and underground obstruction survey to establish the optimum tunnel route, bearing in mind the many and various constraints.
A series of shafts was sunk to connect directly into the ring main with the purpose of either introducing water at major water-treatment works or acting as pumpout shafts at strategic locations around the capital.
The tunnels and shafts were designed to be built in two phases. Phase 1 was constructed using conventional wedgeblock techniques, but problems were encountered which resulted in increased costs and delay.
Phase 2 therefore necessitated a different approach. The company adopted a completely new strategy by changing the form of contract, purchasing its own tunnel boring machines, and redesigning the tunnel linings.
One of the keys to the success of the ring main was the new expanded wedgeblock concrete lining. Design calculations were prepared and finite element analysis work was carried out. The new rings were subjected to build and load tests, both on individual segments and complete rings, using specially designed test rigs.     

Modelling the Potential Effects of Climate Change on the Grande Dixence Hydro-Electricity Scheme, Switzerland

For mountain communities which depend upon glacierfed hydro-electric power schemes as an important source of energy, climate change poses a considerable threat. However, relatively few studies have examined this threat by investigating the joint impacts on meltwater production and energy use. In this paper, a simple water-balance model is used to combine the results of ice-melt and energy-demand models to estimate the water level for the Grande Dixence reservoir, Switzerland. The potential impact of climate change on the scheme is also assessed using a regional climate-change scenario.     

Impacts of Climatic Change on River Flow Regimes in the UK

Much has been written in recent years about the potential threats posed by increasing greenhouse gas concentrations. This paper summarizes the implications of global warming for hydrological processes in general and river flow characteristics in the UK in particular, emphasizing the present high degree of uncertainty. Current climate change scenarios for the UK imply that rainfall between autumn and spring will increase, and this may have beneficial implications for UK water resources. However, the effect of this increase may be outweighed by higher evapotranspiration. Average annual runoff in a catchment in southern UK may be reduced by around 5% by the middle of the next century, but this estimate is very uncertain: runoff may reduce by 30% or increase by 30%. Runoff in northern and western UK is likely to show a slight increase (but with similarly large confidence intervals). It is probable that river flows in the UK will be much more concentrated in winter than at present. The effect of a given climate change scenario on monthly flow regimes depends on the current summer water balance and on catchment geological conditions.     

Hydrology and water quality of the headwaters of the River Severn: Stream acidity recovery and interactions with plantation forestry under an improving pollution climate

This paper presents new information on the hydrology and water quality of the eroding peatland headwaters of the River Severn in mid-Wales and links it to the impact of plantation conifer forestry further down the catchment.The Upper Hafren is dominated by low-growing peatland vegetation, with an average annual precipitation of around 2650 mm with around 250 mm evaporation. With low catchment permeability, stream response to rainfall is “flashy” with the rising limb to peak stormflow typically under an hour. The water quality is characteristically “dilute”; stormflow is acidic and enriched in aluminium and iron from the acid organic soil inputs. Baseflow is circum-neutral and calcium and bicarbonate bearing due to the inputs of groundwater enriched from weathering of the underlying rocks. Annual cycling is observed for the nutrients reflecting uptake and decomposition processes linked to the vegetation and for arsenic implying seasonal water-logging within the peat soils and underlying glacial drift. Over the decadal scale, sulphate and nitrate concentrations have declined while Gran alkalinity, dissolved organic carbon and iron have increased, indicating a reduction in stream acidification.Within the forested areas the water quality is slightly more concentrated and acidic, transgressing the boundary for acid neutralisation capacity as a threshold for biological damage. Annual sulphate and aluminium concentrations are double those observed in the Upper Hafren, reflecting the influence of forestry and the greater ability of trees to scavenge pollutant inputs from gaseous and mist/cloud-water sources compared to short vegetation. Acidification is decreasing more rapidly in the forest compared to the eroding peatland possibly due to the progressive harvesting of the mature forest reducing the scavenging of acidifying inputs. For the Lower Hafren, long-term average annual precipitation is slightly lower, with lower average altitude, at around 2520 mm and evaporation is around double that of the Upper Hafren.     

A Two-Speed Landscape: The Reforestation of the Thames Estuary

Tom Noonan describes how, for this award-winning project, he took up the pen and developed a hybrid drawing technique that exploited the benefits of both the analogue and the digital - characterised by the tactility of the hand and the precision of the computer. He explains that a preoccupation with representation was further ‘reflected and supported by the programme, narrative and language of the architecture’.     

冲刷模型在屋面径流计算中的应用

在监测、分析上海市城区屋面径流水质的基础上,考察了应用冲刷模型估算水质模型参数的可行性.结果表明,该方法可以在数据较少的情况下估算参数,并大大简化了估算的过程,为屋面径流水质模型的应用奠定了基础.     

Modelling algal behaviour in the river thames

Forecasting the movement and growth of algae in river systems as particularly important for operational managers responsible for the distribution and supply of potable water. Algae affect the taste and smell of water and pose considerable filtration problems at water treatment plants. In a collaborative study with the Thames Water Authority, algal models have been developed for the River Thames. The non-linear processes controlling algal growth are examined using a generalized sensitivity analysis technique and the dominant parameters controlling system behaviour are identified. The extended Kalman filter (EKF) is then used to estimate these important parameters. The technique of using generalized sensitivity analysis prior to EKF estimation is suggested as a pragmatic approach to the problem of identifying the subset of physically, chemically or biologically meaningful parameters controlling system behaviour in mechanistic models.     

城市雨水径流面污染负荷的计算模型

对城市雨水径流的污染负荷进行定量分析评价是制定控制策略和实施有效总量控制的基础，为此建立了一种计算城市径流面污染负荷的数学模型，它具有参数少、因果关系清楚、简便直接等特点。利用该模型可对城市径流非点源污染进行量化分析并合理确定初期雨水径流控制量，这为城市径流污染控制决策的制定提供了一种有效的分析方法。     

Modelling the Impacts of Climatic Change on Water Resources

Following the prolonged drought at the end of the 1980s in the south east of the UK, Anglian Water undertook (a) to review the reliable yields of their resource systems and (b) to investigate the potential risks associated with alternative future investment programmes. One of the major identifiable risks is climate change, and there is a clear need to understand how different scenarios of climate change could affect the reliable output of existing sources, and thereby affect investment programmes.
This paper highlights the approach which was adopted to model climate change impacts on rainfall, and on the limitations which exist for this type of assessment.     

The British river of the future: How climate change and human activity might affect two contrasting river ecosystems in England

The possible effects of changing climate on a southern and a north-eastern English river (the Thames and the Yorkshire Ouse, respectively) were examined in relation to water and ecological quality throughout the food web. The CLASSIC hydrological model, driven by output from the Hadley Centre climate model (HadCM3), based on IPCC low and high CO₂ emission scenarios for 2080 were used as the basis for the analysis. Compared to current conditions, the CLASSIC model predicted lower flows for both rivers, in all seasons except winter. Such an outcome would lead to longer residence times (by up to a month in the Thames), with nutrient, organic and biological contaminant concentrations elevated by 70-100% pro-rata, assuming sewage treatment effectiveness remains unchanged. Greater opportunities for phytoplankton growth will arise, and this may be significant in the Thames. Warmer winters and milder springs will favour riverine birds and increase the recruitment of many coarse fish species. However, warm, slow-flowing, shallower water would increase the incidence of fish diseases. These changing conditions would make southern UK rivers in general a less favourable habitat for some species of fish, such as the Atlantic salmon (Salmo salar). Accidental or deliberate, introductions of alien macrophytes and fish may change the range of species in the rivers. In some areas, it is possible that a concurrence of different pressures may give rise to the temporary loss of ecosystem services, such as providing acceptable quality water for humans and industry. An increasing demand for water in southern England due to an expanding population, a possibly reduced flow due to climate change, together with the Water Framework Directive obligation to maintain water quality, will put extreme pressure on river ecosystems, such as the Thames.     

城市暴雨模型发展现状与趋势

20世纪70年代以来,世界上已涌现出百多种城市暴雨模型用于排水系统的规划、设计和运行管理,以有效建设排水系统、减少内涝灾害,实现暴雨雨水的管理。文中系统地讲述了城市暴雨模型的相关概念及理论方法,例举了三个有代表性的城市暴雨模型的主要特征,并介绍了国内情况及发展趋势。     

地铁资源管理模式研究

地铁以其快捷、方便、价格低而受到了人们的欢迎,而在地铁的资产资源管理过程中,如何有效地进行管理,从而提高地铁的经济效益呢？本文就主要介绍了国内外地铁经营现状以及大型的地铁商业模式,阐述了地铁资产及资源管理的相关模式。     

Commissioning and Operation of the Thames Water Ring Main

In order to achieve the earliest possible benefits of the investment in the Thames Water ring main, in late 1989 it was recognized that it was necessary to establish a commissioning team. The remit for the team was to progressively commission the ring main to match the construction programme, without risking the integrity of the daily water supply.
This paper describes the methods, accountability, and achievement of the commissioning project.     

蒙古国图木尔廷—敖包锌矿南部水源地勘探方法

文章通过对蒙古国图木尔廷—敖包锌矿南部水源地水文、气象、地质构造及地下水的补给、径流、排泄条件的分析与研究,利用勘探成果和抽水试验资料,圈定了洼地一带作为成井区段,以袭夺潜水蒸发量为地下水开采量。通过数值模拟法评价水源地地下水天然资源量和可采资源量,找到了满足矿山生产用水的理想水源地。     

低影响开发设施组合的水文模拟及不确定性分析

在海绵城市建设中,通过多种低影响开发(LID)设施的组合应用可实现对城市雨水径流的调控。针对LID设施组合的水文模拟存在高维参数估值不确定性分析的难题,以深圳环保产业园LID示范区为例,构建LID组合设施的暴雨洪水管理模型(SWMM),结合Morris筛选法与DREAM算法,对不同降雨条件下模型中不同设施、不同类型参数的灵敏度和不确定性进行分析。结果表明,位于下游的设施参数灵敏度普遍高于上游设施,排水及导水相关参数灵敏度相对较高;下游设施的排水参数后验分布峰值明显,参数不确定性小;中等强度降雨事件模拟结果的不确定性比高强度降雨事件要小。     

Escherichia coli contamination of the river Thames in different seasons and weather conditions

Contamination of public water ways with sewage represents a serious environmental and health risk. We monitored pollution of the river Thames by enumerating the indicator organism Escherichia coli. Samples were taken from a site in central London near Waterloo Bridge in different seasons. E. coli were quantified using a membrane filtration method, and correlated with the tidal variations of the river and meteorological data on rainfall and temperature. More frequent and severe incidents of pollution occurred in the autumn. Heavy rainfall resulted in sharp peaks of E. coli contamination that implies a potential increase of numbers of pathogenic micro‐organisms. Sixty percent of all samples were found to be in excess of the accepted upper limit of pollution set by European Union (EU) legislation for bathing water. This study demonstrated that frequent sewage pollution of the Thames results in high numbers of E. coli and incidents of detectable levels of pathogenic bacteria demonstrating the need for regular monitoring of bacterial pollution.     

水质模型及其应用研究进展

运用系统分析技术进行水污染控制系统的规划是现代水质管理的基础和依据，水质模型对整个规划过程起着至关重要的作用。较详细地综合评述了近年来国内外水质模型及其应用的研究进展，并评价了水质模型研究的发展趋势，旨在促进相关研究的发展。     

A pilot study of the efficacy of residuum lodges for managing sediment delivery to impoundment reservoirs

Residuum lodges comprise small dams constructed on feeder streams immediately before they enter a reservoir, behind which ponds form, where sediment is deposited. Despite their construction on many impoundment reservoirs (IRE) and catchwaters, little research has previously investigated their efficacy at removing sediments from feeder streams. The current pilot study has, therefore, been carried out at an IRE supplying Halifax, West Yorkshire, UK, where a residuum lodge was recently cleaned out. Sediment concentrations reaching the reservoir were reduced by up to 42% although no certain impacts were noted on the other water quality variables that were measured. Moreover, it was found that the clearance operation did not result in the release of excessive quantities of sediment into the reservoir. It was estimated that the cleared residuum lodge would take 12 years to refill. A survey of other residuum lodges in the Yorkshire region showed there to be considerable differences in their remaining capacities.     

基于IHACRES和GLUE的降雨径流过程模拟

根据降雨径流过程的特征,修正了IHACRES水文模型,并将其与GLUE方法结合,提出了资料缺乏区域降雨径流的分析方法,该方法包括模型参数范围的确定、参数组的筛选与权重的计算、验证与不确定性评价、预测等。利用该方法对深圳石岩河流域两场降雨径流过程的分析表明:模型校准和验证的Nash效率系数R2分别为0.917和0.59,验证时实测径流量基本位于90%置信度预测区间内。该方法对研究流域降雨径流过程的模拟效果较好,径流预测及其不确定性分析可靠,其结果可为资料缺乏区域初期雨水截留规模的设计和方案优化提供依据。