EU- Project: EVK1-CT-2002-00110 ______
AISUWRS Assessing and Improving Sustainability of Urban Water Resources and Systems
FINAL PROJECT REPORT
(Section 6 of the 3rd Annual Report)
Department of Applied Geology
Commissioned Report 12/2005
Consortium: University of Karlsruhe, Germany (Coordinator) British Geological Survey, United Kingdom Commonwealth Scientific and Industrial Research Organisation, Australia GKW Consult, Germany Institute for Mining & Geology (IRGO), Slovenia University of Surrey, United Kingdom
www.urbanwater.de
Department of Applied Geology, Karlsruhe University (TH) Kaiserstr. 12 - 76128 Karlsruhe – www.agk.uni-karlsruhe.de
Assessing and Improving Sustainability of Urban Water Resources and Systems
Final Project Report
L. Wolf, J. Klinger, C. Schrage, U. Mohrlok, M. Eiswirth †, H. Hötzl. Karlsruhe University (TH), Karlsruhe, Germany
S. Burn, Dh. DeSilva, S. Cook, C. Diaper, R. Correll, J. Vanderzalm CSIRO (Melbourne/Adelaide), Australia
J. Rueedi, A.A. Cronin Robens Centre of Public and Environmental Health, Univ. of Surrey, UK
B. Morris, M. Mansour British Geological Survey, Wallingford, UK.
P.Souvent, B. Cencur-Curk, G.Vizintin IRGO, Ljubljana, Slovenia
U. Voett, U. Arras GKW Consult, Mannheim, Germany
K. Höring, C. Rehm-Berbenni Futuretec GmbH, Bergisch Gladbach, Germany
Karlsruhe, AGK 2005
Project website: www.urbanwater.de Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 1
Table of Contents
1 Introduction ...... 3 1.1 Background on urban groundwater management ...... 3 1.2 AISUWRS scope and objectives...... 5 2 Scientific achievements...... 8 2.1 Model Developments ...... 8 2.1.1 Overview...... 8 2.1.2 Urban Volume and Quality Model (UVQ) ...... 8 2.1.3 Network Exfiltration and Infiltration Model (NEIMO)...... 11 2.1.3.1 Introduction...... 11 2.1.3.2 Model Development...... 11 2.1.3.3 Model Validation ...... 11 2.1.3.4 Model Output ...... 12 2.1.3.5 Conclusions ...... 12 2.1.4 Unsaturated Flow Model (ULFLOW) ...... 12 2.1.4.1 Objectives...... 12 2.1.4.2 Methodology and scientific achievements...... 13 2.1.4.3 Socio-economic relevance and policy implications ...... 16 2.1.4.4 Discussion and conclusion ...... 16 2.1.5 Unsaturated Transport Models (SLeakI & POSI) ...... 17 2.1.5.1 Introduction...... 17 2.1.5.2 SLeakI...... 17 2.1.5.3 POSI ...... 18 2.1.5.4 Conclusion...... 18 2.1.6 The Decision Support System ...... 18 2.1.7 The groundwater models ...... 20 2.1.8 Socio- Economic Assessment GKW/Futuretec ...... 22 2.1.9 Sustainability Analysis GKW/Futuretec ...... 23 2.2 Case Studies...... 24 2.2.1 Rastatt...... 24 2.2.1.1 Background...... 24 2.2.1.2 Field studies...... 24 2.2.1.3 Model Application ...... 27 2.2.1.4 Socio Economic Aspects and Sustainability Analysis ...... 32 2.2.2 Doncaster...... 33 2.2.2.1 Background...... 33 2.2.2.2 Field studies UNIS/BGS ...... 34 2.2.2.3 Model Application UNIS/BGS...... 36 2.2.2.4 Socio Economic Aspects and Sustainability Analysis ...... 38 2.2.3 Ljubljana...... 39 2.2.3.1 Background...... 39 2.2.3.2 Field studies...... 40 2.2.3.3 Model Application ...... 42 2.2.3.4 Socio Economic Aspects and Sustainability Analysis ...... 47 2.2.4 Mt Gambier ...... 48 2.2.4.1 Background...... 48 2.2.4.2 Field studies and Attenuation of Contaminants...... 49 2.2.4.3 Model Application ...... 51 2.2.4.4 Socio Economic Aspects and Sustainability Analysis GKW/Futuretec ...... 52
3 Conclusions including socio-economic relevance, strategic aspects and policy implications ...... 54 3.1 Scientific conclusions...... 54 3.2 Socio-economic relevance...... 54 3.3 Strategic aspects & policy implications...... 55
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 2
4 Dissemination and exploitation of the results ...... 57 4.1 Dissemination pathways (AGK/BGS)...... 57 4.2 Future availability and applications of the AISUWRS approach...... 58
5 Literature produced within the AISUWRS project ...... 58
6 Additional References ...... 67
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 3
1 Introduction
1.1 Background on urban groundwater management
The management of urban groundwater resources is often neglected as they are frequently polluted and not usable for drinking water purposes due to quality restrictions. However, also the quantitative aspects of urban groundwater management can be of significance to the urban community. Especially the coupling of urban water supply and drainage systems on the one hand and the urban groundwater on the other hand has led to serious problems in cities world-wide. The most common problems are summarized in Table 1-1. Driving forces for these developments are (a) increasing urbanization, (b) population growth, (c) demand change and (d) climatic change. These forces impose pressures on the planning of urban water supply and drainage systems. Table 1-1: Urban groundwater problems and their consequences (Wolf et al. 2005) Groundwater Status Potential Consequences Example Cities Rising groundwater Cellar & basement flooding, London, Hamburg, Berlin, Barcelona levels increased infiltration of (Kofod 2001), Moscow (Dhzamalov groundwater into the sewer 2001),Buenos Aires systems, increased construction costs for new buildings, etc. Declining groundwater Water scarcity, land subsidence, Mexico City, Bangkok, Venice. levels (in topmost or damage to buildings, drying of deeper aquifers) groundwater dependent aquatic habitats, increased flooding danger in coastal cities (e.g.Venice) Water quality Health risks, usage restrictions, Almost every urban area. Example for deterioration water scarcity fatal consequences: Lusaka.
By 2030 it is estimated that more than 60% of the world’s predicted population of 8400 million will live in towns or cities (UNCHS 1997), with much of the increase concentrated in the developing world. Cities large and small depend on aquifers for their water supply; about half of the world’s megacities are groundwater-dependent (Table 1-2), as are hundreds of smaller cities worldwide. Table 1-2: Population 1996 (and 2015 projected) of megacities dependent on groundwater* (population statistics from UNDES 1994, 1996)
City Population City Population City Population Mexico City 16.9 (19.2) Buenos Aires 11.9 (13.9) Cairo 9.9 (14.4) Calcutta 12.1 (17.3) Jakarta 11.5 (13.9) Tianjin 9.6 (13.5) Teheran 6.9 (10.3) Dhaka 9.0 (19.5) London 10.5 (10.5) Shanghai 13.7 (18.0) Manila 9.6 (14.7) Beijing 11.4 (15.6) * Groundwater dependency definition The city’s water supply (public and private domestic, industrial and commercial) could not function without the water provided by a local urban or peri-urban aquifer system. Typically groundwater would provide at least 25 per cent of the water supply to such a city, and often much more.
In Europe, where urban piped water supply is generally provided by water utilities (as opposed to individual domestic boreholes), some indication of the important role of groundwater in urban water supply can be gauged from Table 1-3. It has been estimated that over 40% of the water supply of Western and Eastern Europe and the Mediterranean region comes from urban aquifers (Eiswirth et al. 2002). In Australia too, groundwater is a valuable urban resource, providing water to consumers in Perth, Newcastle and many smaller towns.
Groundwater’s role in urban development is especially critical where key aquifers are located below the city or in the immediate periurban zone. Here the urban services of water supply, waste disposal and engineering infrastructure interact strongly with each other and with the underlying groundwater system.
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 4
Table 1-3: Importance of groundwater in public supply in various EC Member States Country % groundwater in % urban Country % groundwater in % urban public water supply population(1996) public water population(1996) supply Denmark 99 85 France 56 75 Austria 99 64 Ireland 50 58 Italy 80 67 Greece 50 59 Germany 72 87 Sweden 49 83 Netherlands 68 89 U.K. 29 89 Belgium 52 97 Portugal 80 36
Yet in comparison with cities reliant on supplies from river intakes or from periurban reservoirs, such urban aquifers remain under-studied and under-protected. In part this is a product of traditional water planning which assumes future water demands will inexorably rise, must be catered for, and will inevitably involve the import of additional sources of water from the city’s hinterland. An associated perception is that usage of urban/periurban aquifers is a relatively transient phase pending such development of more distant pristine sources, once the necessary capital investment can be found. However, urban planners are finding it increasingly difficult to replace a degraded urban aquifer by alternative water sources from the hinterland, where resources may already be fully utilised for agricultural or ecological purposes (Burke and Moench 2000). Moreover, sustainability principles, agreed to by more than 150 countries since the 1992 Earth Summit manifesto mean that in the future, a city fortunate enough to overlie a productive aquifer can no longer regard it as a discardable resource, an asset to be abandoned once dewatered or heavily contaminated. However, in detail, the resultant urban water budget is complex (Figure 1-1). The detailed changes vary from city to city, depending on climatic, geological and developmental setting, on national sanitary engineering practices and maintenance regimes (separate sewers, combined sewers or septic tank drainage) and on local water usage rates, to produce a water balance that is quite distinct from that occurring in adjacent rural areas.
Figure 1-1: Overview of urban water fluxes, estimated for the entire City of Rastatt, SW-Germany. (ETpot = potential evapotranspiration, Renat = natural groundwater recharge, SWrunoff = stormwater runoff into sewers, Infsewer = Infiltration of groundwater into sewers, Exfsewer = estimated exfiltration of
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 5
wastewater from leaky sewers, Exfmains = leakage from drinking water mains). Redrawn from Wolf et al (2005).
The Water Framework Directive (WFD), which came into force in 2000, provides a clear sustainability message in this respect. As part of a comprehensive strategy for managing the water environment, Member States have environmental objectives for groundwater (Article 4.1[b] of the WFD) which require them to: • Prevent or limit the input of pollutants into groundwater and prevent deterioration in status • Protect, enhance and restore all groundwater bodies, with the aim of achieving good status • Reverse upward trends in the concentration of any pollutant. There is also an emerging awareness of the interdependence between the underlying aquifer system, the different urban land uses and the water infrastructure of a city, namely the water supply and sewerage system (Lerner et al. 1990, Foster et al. 1993, Eiswirth 2001) and urban reaches of rivers (Grischek et al. 2001). Cities like Venice, Mexico City or Bangkok have suffered from the overexploitation of their aquifers which has resulted in land subsidence (Morris et al 2003). In contrast, several European cities have already experienced drastically falling water levels during early expansion followed by groundwater flooding at later development stages (London, Birmingham, Paris, Berlin, Hamburg, Moscow, Barcelona). A recent survey of communities in Germany has indicated that about 46 % have experienced problems with high groundwater levels, flooded basements and properties (BWK 2003). A large number of private homeowners are affected as the houses were built according to the water levels prevailing at the time of construction, before reduction in abstraction at nearby groundwater treatment plants caused groundwater level rebound. These cases have become (2006) a major issue in German courts as the homeowners are suing the municipalities. As well as costly adverse effects on existing urban structures (tunnels, road cuttings, basements, foundations), rebound in aquifer water levels adds uncertainty to the design of future engineering projects, impeding redevelopment.
All this points to the need for:
• A better quantification of the urban water cycle for cities overlying aquifers • An improved understanding of how new sources of recharge impact on underlying groundwater quality • Application of that enhanced understanding to improve urban water management, by enabling the effects of deploying different water strategies to be predicted.
1.2 AISUWRS scope and objectives
In the light of the current problems of urban groundwater management as listed in chapter 1.1, it is mandatory to develop appropriate methods to uncover the key processes and modelling tools to support the planning and decision process. The AISUWRS project has covered both aspects, firstly the direct field investigations to measure and describe the impact of cities on urban groundwater resources and secondly the development of new models which ensure the transferability to other cities or other water management practices.
One important objective of the AISUWRS initiative is the analysis of a range of existing urban water supply and disposal scenarios which aim to demonstrate how each scenario differs in its handling of contaminants within different urban water systems (background study and data analysis using GIS- systems). The assessment of sustainability of existing urban water systems requires that the sources of contaminants, their flow paths (and volumes e.g. unaccounted-for water, recharge from leakage etc) and the sinks must be identified for different urban areas, and that quantification of the contaminant loads (e.g. sewage exfiltration, paved area runoff etc) is undertaken (Urban water and contamination model validation and calibration). An important goal of AISUWRS is to deliver an innovative planning tool which makes use of the interpretation of selected trace substance monitoring, for indicators which can be measured regularly both in the urban water network (drinking water, stormwater, wastewater) and in the groundwater areas which are known to be sensitive to pollution. The results obtained in a first investigation stage (field investigations) should allow the introduction, further development and validation of the model in three different European case study cities in the second stage, with the local partners in support. A further aim has been to develop a single decision- support system structure, possibly with minor modifications to suit local case-study conditions. With
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 6 this inovative urban water and contaminant balance model different scenarios will be analysed and assessed in order to plan more sustainable urban water systems (European and global aspect). While some of these conditions may be specific to the selected case study cities, it is expected that the overall approach and methodologies used in AISUWRS will be directly transferable both to other European urban regions and to other cities with similar developmental status. For the verification and validation of the urban water and contaminant balance model as well as of the vulnerability assessment system, detailed field studies will be carried out under natural urban conditions. The selected case study cities have been restricted to three in Europe and a comparison town in Australia. All case study cities offer climate and monitoring stations with good knowledge of the underlying aquifers. In order to protect urban groundwater resources effectively the amount of transported pollutants should be identified and quantified at an early stage. For many urban pollution problems the times between recognition and relief measures are in the range of years to decades. In recent years, surveillance has focused on surface water, with pollution of urban groundwater being neglected. To avoid the further degradation of urban aquifer systems, new urban water management tools and innovative DSS are urgently needed. AISUWRS aims to develop such a management and DSS able to react on different time and space scales. In support of a much needed multi-disciplinary framework for the sustainable management of the water resources in urban areas, the ultimate goal (of which the AISUWRS project is just the first stage) should be to develop a DSS, both for slow groundwater degradation by semi-diffuse contamination as well as for catastrophic accidental impacts (pipeline bursts, tanker spills etc.). Indeed, it is the objective of this project to deduce and establish a DSS, that will make use of innovative pipeline assessment systems and an advanced, new urban water scheduling scheme. This support framework will be delivered together with guidelines for the safeguarding and protection of urban groundwater resources from urban pollution. The overall scope of the AISUWRS initiative is to assess and improve the sustainability of urban water systems with the help of computer tools. Parts of these model tools have been already devel- oped to estimate the water flows and contaminant loads within the urban water system. The models need to represent water and contaminant flows through the existing water, wastewater and stormwater systems, from source to discharge point. Bulk water supply is considered an input into the urban water system. Aquifers that underlie an urban area are also included in the urban water system since they play a role in the supply and disposal of water within urban areas. In the urban water and contaminant balance model called UVQ (Urban Volume and Quality) the system boundaries for contaminant flows are the same with the exception of contaminant flows to groundwater. Flows of contaminants to the groundwater were not considered in the original model but have been added in order to integrate with unsaturated zone and saturated zone flow and transport models further downstream. The complexity of interactions between contaminants and soils requires detailed descriptions of each site (field investigations). The potential loads from different urban contaminant sources (sewer leakages, stormwater overflow etc.) then become available for further modelling with a geographic information system (GIS) and a groundwater model in order to simulate contaminant flows to the urban groundwater system (Figure 1-2).
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 7
UVQ
Digital Topographic Map (DTK)
Digital Landscape Model (DLM)
Digital Soil and Soil Parameter Map (BK, BKK)
Digital Sewer Map GIS Automatic Property Map (ALK)
Digital Hydrogeological Map
Digital Geological Map (GK)
Groundwater model
Figure 1-2: Linking different compartments and models by GIS layer concepts.
An objective of the AISUWRS initiative has been to build upon and further develop the concepts of Australia’s urban water program (UWP) to identify and develop systems and technologies, integrative processes and tools of analysis, which are commercially valuable, scientifically robust and which improve the cost effectiveness of urban water services, in line with the project’s vision of ecological sustainability. The existing conceptual urban water and contaminant balance model represents water and contaminant flows through the existing urban water, wastewater and stormwater systems, from source to discharge point. There is a growing interest throughout the world in studying the sustainability aspects of water management. It is clear that the social, economic and institutional dimensions of water problems are often the cause of severe deadlocks. Nevertheless, much more attention has been paid so far to the purely technological problems of water management. In fact, comparative studies on the sustainability of the whole urban water system are still not frequent, yet they can provide a good insight into the aspects that are specific for each country and common to all countries. It is clear nowadays that solving water problems requires not only adequate technologies but also a insight in the social, economic, legal and institutional dimensions of these problems. In the AISUWRS initiative these dimensions will be investigated and analysed comparing the different approaches in various countries.
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 8
2 Scientific achievements
2.1 Model Developments
2.1.1 Overview
The AISUWRS modelling approach comprises all urban water fluxes from source to sink. The urban water cycle considerations start with the public and private water supply and the rainfall as the primary sources of water and solutes (Figure 2-1). On the water supply side the first diversion of the flow occurs already in the pipe systems, which are leaking in every known city (the extent varying from 5% to 80 % leakage). The water losses contribute to the soil moisture in the unsaturated zone or feed directly into the groundwater. This contribution to the groundwater recharge is usually of drinking water quality and poses no threat. Only in areas with significant soil contamination it may enhance the downward transport of contaminants. The percentage of water which actually reaches the customer is then used for a variety of purposes in the households which may be grouped into kitchen, bathroom, toilet and laundry. During each of these uses, solutes and contaminants are added to the previously clean water. Standard rates known from literature are used to describe the added loads per capita per day and a rough wastewater composition is calculated. The generated wastewater is drained into a sewer system for which three outputs are known: sewer leaks, combined sewer overflows and the wastewater treatment plant. The wastewater which leaves the sewer through the manifold leaks enters the unsaturated soil zone and is a large portion of its contaminants are absorbed or degraded on their further way downward to the groundwater table, depending on the travel time, the degree of organic matter in the sediment, the availability of oxygen and the establishment of an adapted microbiological community. Once inside the aquifer, the processes of contaminant removal and degradation slow down considerably. The second route for wastewater to leave the sewers is via combined sewer overflows (CSO). CSO´s occur when the rain intensity causes a hydraulic overload of the sewer system during which the excessive water volumes are released either controlled or uncontrolled into the environment. The conventional recipient of the major part of sewage is the wastewater treatment plant where nutrients and some contaminants are removed or degraded before the release into surface waters. Apart from the indoor water uses, a significant part of the water is used for irrigation of gardens and public open spaces. The most voluminous water input in humid climates is precipitation or rainfall. The rain falls either on roofs, paved areas, gardens or public open spaces. While most urban drainage calculations use the concept of integrative runoff coefficients, the AISUWRS models, in this case UVQ, account for the actual area demand of each of these surfaces in one neighbourhood, which provides more flexibility in simulating alternative settings. For each surface type, the amount of runoff is calculated and specified contaminant loadings are added. In this fashion the quantity and quality of the stormwater component in the sewer system is calculated. The stormwater may leave the sewer system via leaks, CSOs or the wastewater treatment plant. Rain falling on unsealed areas like gardens or public open space is entering the soil moisture store. In the soil moisture store the amount of actual evapotranspiration is calculated based on the climate parameters and the available soil moisture at a given time step. The excessive water is passed as seepage water downwards to the groundwater body. For water entering the system via unsealed surfaces, contaminant contributions from sources like fertiliser application or atmospheric deposition are added. The degradation or sorption of these substances in the unsaturated zone is considered by a separate model before they reach the groundwater table. Water which has entered the aquifer is then transported according to the local hydraulic gradient and will finally contribute either to a water supply well, to areas with negative groundwater recharge or to the next surface water system. .
2.1.2 Urban Volume and Quality Model (UVQ)
Urban Volume Quality (UVQ) is a conceptual, daily time step, urban water and contaminant balance model that simulates an integrated urban water system and estimates the contaminant loads and the volume of water flowing throughout the water systems from source to discharge point. As an integrated urban water system it considers the total urban water cycle, comprising the water supply, stormwater and wastewater systems. The urban water system is defined here to be the delivery of water to residential, commercial, industrial and other users within an urban area, and management of the wastewater and stormwater generated within that same area. UVQ has been designed to provide
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 9 flexibility in the manner in which water services are represented and provides the ability to represent a wide range of conventional and emerging techniques for providing water supply, stormwater and wastewater services to either an existing urban area or a site which is to be urbanized.
A typical example of a study area is a suburb which contains residential and commercial neighbourhoods, representing an urban area containing a number of neighbourhoods that have mixture of land uses such as residential, industrial, commercial and institutional.
UVQ uses three spatial scales to represent the urban area, the residential land block, the neighbourhood and the study area scale. UVQ requires configuration parameters for each spatial scale, such as occupancy, garden area, roof area and paved area in a residential land block and open space area and road area in a neighbourhood, before simulating the urban area. Rainfall data is supplied through a climate input file. As output UVQ provides data on quantity and quality (quantified by contaminant levels) of wastewater generated by land blocks, volumes of stormwater and irrigation water infiltrating through open spaces and gardens and of stormwater produced in the neighbourhoods.
UVQ (Urban Volume and Quality) model was developed from an existing CSIRO research modelling tool. The first stage of the Work Package was to determine the requirements of the UVQ model within the AISUWRS project and to evaluate UVQ’s suitability to the task. UVQ was required to provide a link to other models in the modelling suite and so had to produce output files compatible with other model input requirements and with the DSS. UVQ was also required to provide the capability to model alternative scenarios which would be developed in the later stages of the overall project (see Figure 2-1 for final conceptual representation).
Initial development of UVQ focused on the generation of the user interface and integration of the contaminant balance into the existing water balance source code. As UVQ was the first model developed, the exact definition of required output files for links with other models was not possible at this stage of model development. Output files were created but their content and configuration was to be reviewed during later stages of the project once all models and the decision support system were developed.
Following training, UNIKARL applied UVQ to a demonstration catchment and compared the results with measured field data. The results were compiled into a paper (Klinger & Wolf, 2004) and presented at a CityNet event. In addition, UNIS and IRGO also started with the application of UVQ to the Bessacar and Ljubljana study areas and provided further feedback to the developers. The feedback from the UVQ users both in Europe and Australia led to the addition of the following functions to UVQ. • Development and coding of algorithms to allow the representation of snow events in colder European locations • UVQ was enhanced to explicitly represent either combined or separate sewer systems at the neighbourhood scale. UVQ was initially developed for Australian water management options where combined sewers are not standard. • Development of a Results wizard which allows the user to graphically represent many combinations of input and output water or contaminant flows for selected neighbourhoods • Saving and loading of the project and climate files as one • Selection option to generate AISUWRS output files or allow UVQ model to be run as a stand alone tool • Groundwater ingress to wastewater sewer pipes explicitly represented within UVQ, based on user specified monthly ingress rates (litres per day per meter of pipe) for each neighbourhood within a study area
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 10
Rain and snowmelt Evaporation Imported water
Impervious surface Evaporation Actual K B L T Evapotranspiration Irrigation Indoor Water Use
Road Roof Paving GW BW Rainfall Store Store Store Wastewater Excess Septic Disposal treatment
Stormwater Raintank Stormwater Infiltration store store Pervious Store store Non-Effective (Store 1) Leakage Impervious Area Runoff (Store 2) To GW model Pervious Surface Wastewater Bore To GW Runoff Extraction Exfiltration Effective Impervious model Surface Runoff Stormwater store GroundWater Wastewater infiltration Recharge treatment Aquifer storage Stormwater and recovery store To GW model GroundWater BaseFlow Store Inflow (100% for combined system) To PL To PL model model Study area boundary Overflow
K – Kitchen Stormwater Wastewater store treatment B – Bathroom L – Laundry T – Toilet Stormwater Wastewater GW – Greywater runoff discharge BW – Black water to further uses
Figure 2-1: Conceptual representation of UVQ model and links to other models
The UVQ model is the most data intensive of the entire modelling suite, especially in terms of contaminant concentrations. It was a major task for BGS & UNIS to find existing data, to process new data based on existing information (e.g. inhabitants per house, size of pipe leak or pressured main leakage) or to search for adequate data that could be related to the study site in literature (e.g. chemical composition of road runoff or precipitation chemistry). CSIRO provided a database of Australian literature and recorded values of contaminant loads and concentrations to all project partners, which helped alleviate this data gap.
As other models in the modelling suite were developed the content and configuration of UVQ output files was also developed. From discussions with other model developers and users it was decided to calculate flows and contaminants to saturated and unsaturated soil zones and to groundwater in the same way, to ensure continuity in values used. Thus, when operating UVQ in AISUWRS mode, the following output files are produced in the required format and time step. • Total neighbourhood wastewater flows to the Pipe leakage model • Total neighbourhood stormwater flows to the Pipe leakage model • Potable pipe leakage to groundwater • Stormwater infiltration basin to groundwater • Garden and open space area to groundwater
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 11
2.1.3 Network Exfiltration and Infiltration Model (NEIMO)
2.1.3.1 Introduction
The Network Exfiltration and Infiltration Model (NEIMO) is a tool that provides exfiltration and infiltration data on a network scale with input data generally available to water authorities or accessible from public institutions. The NEIMO development was based on the classical Darcy Law on fluid flow through porous media (Eq. 1). (h − h ) Q = −kA a b Eq. 1 L 3 2 [Q = total flow between two points a and b (m /s), K = hydraulic conductivity of the soil (m/s), A = area of flow (m ), ha − hb= hydraulic head drop between the two points a and b (m), L = Distance between the points a and b (m)]
Two individual models on exfiltration and infiltration make up NEIMO. The exfiltration model utilises data on wastewater flow level within the pipe, size and distribution of pipe defects, conductivity of the clogging soil layer immediately outside the defect to determine the exfiltration rate. The infiltration models utilises depth of the pipe below the water table, wastewater flow level within the pipe, conductivity of the surrounding soil and the size and distribution of pipe defects.
2.1.3.2 Model Development
In adapting Darcy equation to sewer exfiltration and infiltration, the soil layer immediately in contact with the sewer defect is considered as the layer controlling the movement of water and responsible for defining the hydraulic gradient. The micro-environment outside the pipe defect is different in the two situations because exfiltrating wastewater clogs up the soil with organic matter reducing the soil permeability. With infiltration clogging is not an issue. As the two mechanisms are different, the application of the Darcy model to infiltration and exfiltration are treated separately.
With exfiltration the wastewater passing through a defect clogs up the soil outside the defect. The permeability of this zone is considered to have a limiting influence, and the Darcy equation takes the form, ⎛ ∆H ⎞ ⎜ Fill ⎟ Eq. 2 QExfiltr. = k Exfiltr. * A*⎜ ⎟ ⎝ ∆LCol ⎠ where, kExfiltrn. and ∆LCol are the specific conductivity and thickness respectively of the clogging (colmation) layer. To apply this model to sewer pipelines ∆HFill is calculated from pipe geometry and fill level data.
For the infiltration model, the soil being saturated, the water moves freely without resistance. Closer to the defect, the model assumes that water is drawn towards the defect by the negative pressure gradient, and this movement rate is determined by 0.1 m thick soil layer surrounding the pipe defect. On this basis the modified Darcy equation for infiltration is,
⎛ ∆H Gw − H Fill ⎞ QInfiltr. = −k Infiltr. * A*⎜ ⎟ Eq. 3 ⎝ 0.1 ⎠ where kInfiltr is the specific conductivity of the soil (m/s). ∆HGw is distance from the groundwater level to the pipe base.
To apply this model to sewer pipes, the defect area A is estimated from direct measurements via CCTV damage inspection reports. However where CCTV data is not available, which is generally the case for majority of assets in a network, NEIMO simulates size of defects, such as cracks and displaced joints, for each pipe asset based on pipe characteristics (material, size, age) and soil type in which it is installed, by reference to generic defect data compiled from CCTV inspection of other sewer networks. The fill levels are determined by applying UVQ output data as the flow from customer connections into the first pipes in a network and the flow into subsequent pipe assets as the flow from upstream pipes as well as that from any additional customer connections.
2.1.3.3 Model Validation
The difficulty of measuring exfiltration in established sewers and the uncertainty on the degree to
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 12 which the colmation layer is established in experimental setups has limited the avenues available for exfiltration model validation. Notwithstanding, in-situ exfiltration measurements were carried out on several Melbourne sewers. In each determination a section of sewer between manholes was isolated, filled with wastewater through the upstream manhole and the exfiltration monitored over several hours via the water level in the manhole. The defects in pipelines were measured and quantified through CCTV inspection. Analysis of the exfiltration data with the model (Eq. 2) produced kExfiltrn values ranging from 8.6*E-05 to 3.4*E-04 m.s-1 which compares well with the range 1.74*E-6 m.s-1 to 3.84*E-4 m.s-1 reported in literature. However the method had some drawbacks in that the pipe was filled to capacity and subjected to an abnormally high hydraulic head. A separate exfiltration exercise on a live sewer with artificial defects and fitted with instruments for real time recording of leakage produced comparable kExfiltrn .
Validation of the infiltration model was through an experimental setup where the pipes with artificial defects were installed in saturated soil, and infiltration measured at hydraulic heads of 0.65 m and 0.85 m. At the time of writing this report the results have not been consistent and the experimental procedure is under review.
To validate of the models over a full network, NEIMO was applied to the sewer system of the city of Mt Gambier. The output from the model indicated an exfiltration of 1.2% from a total inflow volume of 15,092 m3. In a network of 245 km, this averages to a leakage rate of 0.1 L sec.-1 km-1, which compares well with rates between 0.01 and 0.3 L sec.-1 km-1 reported in literature (Blackwood et al., 2005) and a dry weather exfiltration rate of 1.3% to 3.8% estimated for Dresden (Karpf and Krebs, 2004). The NEIMO output uncertainty is in the order of ±50%, which reflects the uncertainly in some input data such as permeability of the limiting layers, their thicknesses, defect sizes, soil types and flow volumes.
2.1.3.4 Model Output
The exfiltration and infiltration models operate on a daily time step. The output from the models for a study area is a single data file with the daily exfiltration volume and infiltration volume (m3/d) for each asset in the network. The concentration of contaminants is provided with the output, using data gained from UVQ.
2.1.3.5 Conclusions
The leakage models combined as NEIMO is a tool that provides exfiltration and infiltration data on a network scale using input data generally available to water authorities or accessible from public institutions. Individual exfiltration and infiltration models were based on the Darcy law on fluid flow through porous media.
NEIMO simulates defects, such as cracks and displaced joints, on each pipe asset in the network, the wastewater flow through the system, the position of groundwater relative to the pipe and determines the leakage from (exfiltration) or into (infiltration) for each asset. The size and distribution of defects are related directly or indirectly to CCTV damage inspection reports. The wastewater flow simulation is obtained from UVQ, which allows NEIMO to track the contaminant loads in the exfiltrating or infiltrating water. The output from NEIMO is passed for subsequent assessment by an unsaturated flow model, treating leakage as point sources of contamination.
Validation of the model has been challenging, especially as direct measurement of exfiltration is an inexact science. In view of the many assumptions made in model development and defect size estimation the uncertainty in the leakage computed is conservatively estimated at 50%
2.1.4 Unsaturated Flow Model (ULFLOW)
2.1.4.1 Objectives
The main objective of WP 6 has been the development of a methodology for modelling urban groundwater recharge with respect to the flow processes in unsaturated soils and their spatial and temporal variability, as well. The basic concept for the quantification of infiltration rates proposed by
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 13
UniKarl (IfH) is the consideration and distinction of different kinds of single urban infiltration sources (precipitation, irrigation, rain water infiltration, water system losses, sewer leakage etc.).
Sensitivity studies have been performed by UniKarl (IfH) for areal and point sources using the recently developed models UL_FLOW (Mohrlok, 2005) and WTM (Bücker-Gittel et al., 2003; Cata & Mohrlok, 2005) respectively to investigate the influence of different soil characteristics and different hydraulic boundary conditions like infiltration rates, depth of groundwater table, soil moisture and pipe leakages. Based on this, a classification of the spatially variations of those sources on the scale of the entire urban area has to be implemented into the data base and DSS by use of GIS methods. The results are correlated with urban groundwater recharge assessments developed by UniKarl, UNIS and BGS.
In contrast to the prior planning the work in WP6 has been focused on the validation of the selected steady state approaches implemented in POSI and SLeakI (WP7) rather than the pure quantification of groundwater recharge in each case study city.
2.1.4.2 Methodology and scientific achievements
Modelling unsaturated flow and groundwater recharge on urban scale is a great issue because of the high variability in soil structure and boundary conditions as well as the non-linearity of the unsaturated water flow problem. These aspects make it impossible to set up a large scale three-dimensional model for the unsaturated zone of the entire urban area. Instead there has been the strong requirement to simplify the problem in an appropriate way, so that major important quantities and their dependencies were represented. In order to be predictive the developed methodology had to be based on physical approaches. The selected approach in the AISUWRS context considers the multiple infiltration sources separately in order to reduce the modelling effort and it enables the coupling of the different models. This approach has been described in the deliverable D13 of the AISUWRS project (Mohrlok & Buecker-Gittel, 2005)
Basically, the dimensionality and complexity of flow pattern, i.e. regional areal source, local areal sources and local point sources, had to be distinguished and required different model approaches. In addition, at each source location the selected model had to take into account different soil profiles, different distances between source and groundwater table and time-depending infiltration rates. For the purpose of AISUWRS it has been decided to use steady state approaches for the unsaturated zone modelling. Since the considered processes are transient on a short time scale the assessment of the steady state assumption has been necessary.
The recently developed pseudo-transient model UL_FLOW (Mohrlok, 2005) based on a steady state analytical solution and a simple time dependent water balance was used to simulate the one- dimensional infiltration from areal sources and to compute residence times of a non-reactive solute within the soil profile between the source and the groundwater table. This model has been documented in the deliverable D14 (Mohrlok, 2005). A sensitivity study was prepared in order to investigate the effect of different soil types, coarse sand and sandy loam, and soil thicknesses on the groundwater recharge rates and residence times for two different infiltration rate time series selected from neighbourhood 11 and 23 defined for UVQ simulations of Rastatt case study (Figure 2-2). Particularly, the influence of the time step sizes, i.e. the temporal averaging, has been in the focus of that investigation. The transient behaviour was more important for the coarse sand since the resulting variance of the calculated time series became larger. Therefore, the steady state assumption is better applicable to the finer than to the coarser grained soils and to lower than to higher infiltration rates. Furthermore, monthly time steps also diminishes those variances.
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 14
Groundwater recharge, neighbourhood 11 Groundwater recharge, neighbourhood 23 [mm/d] [mm/d] 3.0 30 coarse sand coarse sand q_inf, daily q_inf, daily 25 2.5 q_inf, monthly q_inf, monthly daily, 1m daily, 1m 2.0 daily, 2m 20 daily, 2m daily, 4m daily, 4m daily, 8m 1.5 daily, 8m 15 monthly, 1m monthly, 1m monthly, 2m 1.0 monthly, 2m 10 monthly, 4m monthly, 4m monthly, 8m monthly, 8m 0.5 5
0.0 0 0123456789101112 0123456789101112 Month Month Residence time, neighbourhood 11 Residence time, neighbourhood 23 [d] [d] coarse sand coarse sand daily, 1m daily, 1m 10000 10000 daily, 2m daily, 2m daily, 4m daily, 4m daily, 8m daily, 8m 1000 monthly, 1m 1000 monthly, 1m monthly, 2m monthly, 2m monthly, 4m monthly, 4m 100 monthly, 8m 100 monthly, 8m
10 10
0123456789101112 0123456789101112 Month Month Groundwater recharge, neighbourhood 11 Groundwater recharge, neighbourhood 23 [mm/d] [mm/d] 3.0 30 sandy loam sandy loam q_inf, daily q_inf, daily 2.5 q_inf, monthly 25 q_inf, monthly daily, 1m daily, 1m 2.0 daily, 2m 20 daily, 2m daily, 4m daily, 4m 1.5 daily, 8m 15 daily, 8m monthly, 1m monthly, 1m 1.0 monthly, 2m 10 monthly, 2m monthly, 4m monthly, 4m monthly, 8m monthly, 8m 0.5 5
0.0 0 0123456789101112 0123456789101112 Month Month Residence time, neighbourhood 11 Residence time, neighbourhood 23 [d] [d] sandy loam sandy loam daily, 1m 10000 daily, 1m 10000 daily, 2m daily, 2m daily, 4m daily, 4m daily, 8m daily, 8m 1000 monthly, 1m 1000 monthly, 1m monthly, 2m monthly, 2m monthly, 4m monthly, 4m 100 monthly, 8m 100 monthly, 8m
10 10
0123456789101112 0123456789101112 Month Month
Figure 2-2: Groundwater recharge rates and residence times for the soil type coarse sand and sandy loam with different thicknesses and application of infiltration time series (q_inf) with different time steps for neighbourhood 11 and 23 from the Rastatt case study.
The developed extension to the model UL_FLOW_UVQ (Mohrlok, 2005) allows the calculations directly based on the UVQ output files and the neighbourhood data sets and produces output for all neighbourhoods. It has been applied to the Rastatt case study data sets and produced spatially varying time series of groundwater recharge rates and residence times as well. Simple time series
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 15 analyses methods were used to derive representative quantities from these results. These quantities were basis for the produced maps and are demonstrating the spatial variability with regard to soil profile characteristics and depth, and time step size as well (Figure 2-3). a) daily time steps
Rastatt study area Rastatt study area
recharge [mm/a] 30 - 60 61 - 90 min_res_time [d] 91 - 120 10 - 30 121 - 150 31 - 100 151 - 180 101 - 300 181 - 210 301 - 1000 211 - 240 1001 - 3000 241 - 270 3001 - 10000
11::150,000,00000 11::15000,0,00000
0 250 500 1,000 0 25 0 500 1,000 Meters Meters b) monthly time steps
Rastatt study area Rastatt study area
recharge [mm/a] 30 - 60 61 - 90 min_res_time [d] 91 - 120 10 - 30 121 - 150 31 - 100 151 - 180 101 - 300 181 - 210 301 - 1000 211 - 240 1001 - 3000 241 - 270 3001 - 10000
11::150,000,00000 11::15000,0,00000
0 250 500 1,000 0 25 0 500 1,000 Meters Meters c) yearly time steps
Rastatt study area Rastatt study area
recharge [mm/a] 30 - 60 61 - 90 min_res_time [d] 91 - 120 10 - 30 121 - 150 31 - 100 151 - 180 101 - 300 181 - 210 301 - 1000 211 - 240 1001 - 3000 241 - 270 3001 - 10000
11::150,000,00000 11::15000,0,00000
0 250 500 1,000 0 25 0 500 1,000 Meters Meters
Figure 2-3: Groundwater recharge rates and minimum residence times calculated for each neighbourhood at the Rastatt case study by UL_FLOW_UVQ with different time steps; a) daily time step, b) monthly time step, c) yearly time step.
In order to assess the transient behaviour of infiltration from a point source into initially dry soils a parameter study was performed by varying the soil parameters and the infiltration rate applying the numerical model WTM (Bücker-Gittel et al., 2003; Cata & Mohrlok, 2005). However, only a very short infiltration period could be simulated because of the large computational effort. The infiltration source was emplaced about 0.9 m above the groundwater table. Application of solute concentrations as a conservative tracer to that infiltration enabled the estimation of residence times in the unsaturated zone beneath a pipe leak. Tracer was injected as pulse and continuously as well for the several simulated hydraulic conditions.
Depending on the initial conditions the outflow in the simulations started with a certain flow rate and
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 16 steady state flow was reached after a short time depending on the soil properties (Figure 2-4). The breakthrough was depending on the soil hydraulic properties and the infiltration rate. It was found that even for loamy soil and low infiltration rates an early breakthrough was observed after a few hours. However, even for sandy soils a steady state mass flux at the groundwater table was not observed after one day due to large variances of the travel times along the different transport paths within the three-dimensional flow pattern. In general, very low concentrations were observed due to strong dilution effects at the groundwater table.
[L/d] groundwater recharge 20.0 sand, Q_inf = 20L/d 0.0 Q_ref = 20L/d sand, Q_inf = 21.6L/d -20.0 Q_ref = 21.6L/d sand, Q_inf = 100L/d -40.0 Q_ref = 100L/d sand, Q_inf = 100L/d -60.0 loam, Q_inf = 100L/d -80.0 loam, Q_inf = 100L/d
-100.0
-120.0 0 5 10 15 20 25 time [h]
[mg/L] average outflow concentrations 0.10 0.09 sand, Q_inf = 20L/d sand, Q_inf = 21.6L/d 0.08 sand, Q_inf = 100L/d 0.07 sand, Q_inf = 100L/d loam, Q_inf = 100L/d 0.06 loam, Q_inf = 100L/d 0.05 0.04 0.03 0.02 0.01 0.00 0 5 10 15 20 25 time [h]
Figure 2-4: Groundwater recharge development and tracer breakthrough at the groundwater table from point source infiltrations for different soils, infiltration rates and initial conditions simulated by WTM (Bücker-Gittel et al., 2003; Cata & Mohrlok, 2005).
2.1.4.3 Socio-economic relevance and policy implications
The developed methodology has been used to implement the unsaturated flow and transport models POSI and SLeakI (WP7) within the AISUWRS DSS in order to estimate water and mass fluxes to the urban groundwater from different infiltration sources. The developed modelling tools have been used to assess the approaches and reliability of those models.
2.1.4.4 Discussion and conclusion
The assessment of the application of steady state assumptions was performed within a sensitivity study by investigating the transient infiltration behaviour from areal and point sources as well. Using typical soil types from the AISUWRS case study cities and varying the depth of the profile and the time steps the infiltration behaviour from areal sources derived the limitations of the steady state assumption with regard to flux rate and residence time. The application of the model UL_FLOW_UVQ
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 17
(Mohrlok, 2005) could demonstrate the spatial variability of groundwater recharge rates and residence times for the Rastatt case study. The three-dimensional case of point source infiltrations was investigated only for a few number of configurations applying the numerical model WTM (Bücker-Gittel et al., 2003; Cata & Mohrlok, 2005) due to the large computational effort.
These investigations showed the necessity to account for the different variabilities for the AISUWRS model application. However, simple steady state approaches like implemented in POSI and SLeakI models (WP7) are basically required to be able to set up water and contaminant balances for the entire urban water systems with a reasonable effort. Since these assumptions are not able to represent the soil storage effects the selection of appropriate infiltration rates representing the temporal variations is essential. Simple transient approaches would be desirable combined with statistical time series analyses with respect to further risk assessment.
2.1.5 Unsaturated Transport Models (SLeakI & POSI)
2.1.5.1 Introduction
This section describes the approach used in modelling the transport and attenuation/magnification of potential groundwater contaminants through the unsaturated zone. Water and contaminants, either from direct infiltration through pervious surfaces or from point contamination sources which are typically from leaks in pipes, may pass through the soil to reach the groundwater. In reality the soil is non-uniform, but in the AISUWRS study it has been assumed that that the soil is comprised of uniform layers and in the cases studies this has been limited to two layers. Two approaches have been developed in the course of the AISUWRS project to model the transport of contaminants in the unsaturated zone.
2.1.5.2 SLeakI
The first approach considers leaks from pipes (SLeakI). It is assumed that each leak occurs in a pipe that is bedded in sand in a trench. It is further assumed that a colmation layer will be formed below the leak. This colmation layer serves to limit the rate of flow from the leaks and also removes a high proportion of the microbes. The flow path of water leaking from the pipe will be determined, among other things, by soil texture. Necessary inputs to SLeakI include soil properties and the flow rate from the leak. The leak data in the AISUWRS study is provided by the NEIMO output (leak volume and contaminant concentration) of each asset in the pipe network. These data are used to estimate the path through each soil layer, and the residence time of water in that layer.
The residence time can be estimated by a crude method or a sophisticated method. Both methods require simplifying approximations. These approximations assume that there are two soil layers and that the soil layers are homogenous, non-swelling and from a standard texture class. This latter assumption enables the use of standard soil properties relating hydraulic conductivity to soil moisture and soil moisture to capillary head. These data are embedded within the various models. A further simplifying approximation is that there is a steady state with respect to moisture. In practice this may not be so.
The naive method effectively assumes that the soil below the leak will be wetted, and that the wetted volume will be in the shape of a cone. The volume of water in the cone can be estimated - given a flow rate into the cone, the time to replace all the water can be estimated for a single layer. Flow through a second layer assumes that there is a truncated cone, and again that time can be estimated as the time to replace that volume of water. The water content and cone shape are obtained from a lookup table for each soil type. The naive approximation gives realistic results and has the advantage of being easy to implement, especially in a spreadsheet program. The source of error in using this method is in the uncertainty of the shape of the cone, and of the associated parameters. The best angles for the conical approximation have been estimated from the sophisticated method using different soil types and depths. The sophisticated model implemented for the estimation of residence time is described by Robinson (2005) in a report commissioned for this project. The model is 3- dimensional, with the x-y coordinates initially describing the horizontal movement and a z coordinate describing the depth. The radial symmetry can be exploited by using polar coordinates for the lateral movement of the water.
During the development of the model, it became clear that rather than a single program, there was a requirement for separate programs. These include a fast batch program that interfaces with the
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 18 databases from a cities infrastructure, containing records on each leaking pipe. These records include sewage quality, flow rate, depth to the water table and soil parameters. The program returns point estimates of contaminant loads from that particular leak to the groundwater. This was the main brief for this component of the project. As part of the development of the batch component, it was necessary to develop an interface for use by stakeholders, which led to the development of a package (SLEAKI) that can be used to assess the loadings from a particular leak. This package is user-friendly and provides graphical output of the estimated loads on the ground water for that leak,
2.1.5.3 POSI
The second approach is a simpler 1-D model that is used for the description of infiltration beneath urban green areas and other public open spaces and has been developed into a package. A 1-D model can be used where contaminants are carried to the groundwater from a large open space. Examples of large open spaces where contaminants are spilt or used are a public lawn area (bowling green, golf course, playground, parkland), household lawns and gardens or house areas where other activities (e.g. cleaning the family car). Sources of contaminated water in a public open space include stormwater, rainfall and septic seepage. In each case it is assumed that the area of infiltration is known and is sufficiently large that localised variations and edge effects can be ignored
The POSI program is based on a simple one-dimensional model of the steady state infiltration of surface water through an unsaturated soil to the water table. The soil is treated as a layered medium with two homogeneous layers. This model should provide a reasonable approximation to infiltration over large, open areas. In particular, it will give an estimate of the typical time for a small sample of water to travel from the surface to the water table.
POSI considers infiltration from below the root zone. However, much of the available information will be relevant to the surface layer. There is a gap in the model chain that is not covered by AISUWRS. This will necessitate the inclusion of factors that affect both the amount of water and contaminants that reach the groundwater. To enable progress to be made, the following guidelines should be used. • Nutrients applied should be considered as conservative, so the amount added will be what is passed to below the root zone. • Pathogen concentrations would be reduced in this zone, but at this stage this reduction can not be quantified (although it probably would be quite significant). Because of this a conservative approximation of no reduction should be used for this layer. This area requires further work. • Organic compounds would be retarded especially by organic matter in the soil. This would vary between compounds depending on their Koc partitions. The amount of reduction depends also on their half lives. The theory for this has been considered by Kookana et al. (2004) and could be transferred. • A fraction of the water applied would be lost due to evapotranspiration. A water balance model where evapotranspiration is taken as 0.7 pan evaporation could be used to estimate water loss. The amount of infiltration would then be estimated by subtracting evapotranspiration from the applied water. Many other models are available for this component but they require significant input parameters. A useful approach may be to consider soil dryness in the spirit of Mount (1972).
2.1.5.4 Conclusion
Water managers need to make decisions concerning the protection of the groundwater. The models described seek to provide decision makers with tools to assist in the maintenance of their infrastructure through informed decision-making. The unsaturated transport models enable improved information on the transport and likely attenuation/magnification of contaminants as they move through the unsaturated zone towards the groundwater.
2.1.6 The Decision Support System
The DSS links the individual models together and supports the selection and comparison of predefined scenarios (Figure 2-5). The most prominent function of the DSS was to provide a common platform with a graphical user interface that controls a number of complex models and allows for the passing of information between models. The interface enables the user to set key parameters for each of the models, run the model chain and then view a summary of the output file. It was envisaged at the beginning of the AISUWRS project to develop a tool which identified preferred strategies for the
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 19 sustainable management of urban groundwater resources, however, the research undertaken has shown that the complexity of a technical urban water system interacting with a heterogenous natural system requires a very detailed site-specific analysis and understanding of the involved processes.
The DSS enables users to track potential groundwater contaminants from the source, such as a leaking sewer, and the attenuation and movement of contaminants through the unsaturated zone until they reach the aquifer. The major benefit from the application of the DSS is to provide a holistic urban water system tool that enables water services to be represented in a flexible manner and provides the ability to represent and investigate the implications of a wide range of conventional and emergent techniques for providing water supply, stormwater and wastewater services. Users are also able to explore the likely implications of critical uncertainties such as changes to water consumer behaviour or climate change. The DSS allows for the processing of predefined scenarios, and the quantification of key indicators for scenario evaluation. This will allow end-users to develop best practice response to different scenarios based on the potential for groundwater contamination. For example; modifying customer preferences, groundwater treatment or introducing system improvements that minimise contamination. A comprehensive output summary table is produced for each scenario. The output of the DSS is then available for further implementation into numerical groundwater flow and transport models. The primary data pathways are detailed in Figure 2-6.
Flow diagram for DSS UVQ Urban water usage and stormwater generation
PlmUVQ UFMUVQPOS WWinput.txt input.txt WW Open Space flow contaminant contaminant load & load & volume volume
Soil SW pipe Water pipe NEPLIMMO WW pipe LeakLeakageage ffrromom WWWW s seewweerrss POSI Open space InfiltExfilt.csv infiltration through Garden irrigation, + some UVQ data SW Bore Soil soil to GW water pipe leakage (only in Mt.G) and SW infiltration from Public Open Space SLeakI WW leakage through soil to GW
Soil
MODFLOW Groundwater aquifer FeFlow HACCP
Figure 2-5: Visualisation of modelling concept in the DSS.
Scenario analysis requires the groundwater contamination potential to be analysed over a period of many years and in most cases decades. However, the computation resources required by the NEIMO for a typical sewer network (total length greater than 100 km) for this time frame is very high, and it is not practical to perform the calculations for those periods. The solution to this has been to design the DSS to initially analyse the UVQ output data and identify 4 days that represent typical dry weather flow, medium wet weather flow, heavy wet weather flow and storm weather flow. The DSS then performs the NEIMO calculations on medians of these representative 4 days allocated on a yearly basis over the time frame required and passes the output to SLeakI to assess groundwater contamination from pipeline leaks.
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The AISUWRS DSS is linked to a MS-Access compatible database which stores the relevant input and output information of the different models. In addition, the relevant information is also available in plain text files which are produced by the submodels to communicate with the DSS system. The database system stores each model run together with a limited set of metadata and allows for easy access to results from different scenarios. The direct linking of the database content to geographical information systems is possible but is not included in the standard version.
UVQ OUTPUT UVQ Water & Contaminant Properties Potable leakage Population Housing Industries Selection of 4 Typical days Schools Roads Parks Waste & Storm Climate Water Properties Water to; Public Open Spaces CASE PLM Gardens STUDY Leakage from CITY Wastewater Water supply Asset data PLM OUTPUT DATA Soil types, Water leakage per asset GW Depth Population Housing Industries SLeakI POSI Schools Roads Areas of Parks Study zone SLeakI OUTPUT POSI OUTPUT Neighbhds. Wastewater Assets Water & Contaminant Water & Contaminant Soil types travel time travel time Climate data
Contaminant Quantities to GROUNDWATER
Figure 2-6: Primary data management pathways in the DSS.
The set up and calibration of the groundwater models is a complex task and the choice of methodology depends highly on the local hydrogeological framework as well as on the experiences and preferences of the users. In the four AISUWRS case study cities, three different approaches and software packages are employed. As a consequence, the groundwater models are not integrated within the DSS user interface. However, the DSS provides a generic interchange file that can be used as an input to a wide range of groundwater models.
In combination with groundwater transport models and a socio-economic assessment, the Decision Support System provides a comprehensive tool to assess the implications of different urban water practices on the sustainability of groundwater resources.
2.1.7 The groundwater models
Groundwater is the central urban water resource considered in the AISUWRS project. One of the main goals is to describe the impact of varying urban water scenarios on urban groundwater resources. In accordance to the grossly different aquifer types and hydrogeological settings in the case study cities, different approaches are used in the respective case study cities.
Numerical groundwater models divide the aquifer into a grid or mesh of cells or elements and solve the flow and transport equations at each node. An example of a finite element mesh constructed with FEFLOW for the domain Rastatt-Danziger Strasse is depicted in Figure 2-7.
The basic input data for the groundwater models are the geometry and hydraulic properties of the aquifer system, the groundwater recharge rate and the flow conditions at the model boundaries including the water levels in rivers and lakes. In the AISUWRS context, the models receive the
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 21 information on groundwater recharge either from the DSS or directly from the output files of the UVQ and NEIMO models. This includes both flow volumes and contaminant concentrations. The main outputs of the groundwater models are the spatial distribution of hydraulic heads, the distribution of mass concentrations and the spatial distribution of travel times.
Figure 2-7: Finite element mesh of the medium scale groundwater model at Rastatt-Danziger Strasse.
In Rastatt the proprietary software code FEFLOW has been chosen for the numerical simulations. Three different model scales have been considered. A small scale model has been analysed to calculate the effects of the known sewer leak at Danziger Strasse on the shallow groundwater monitoring wells in the immediate vicinity. Steady state models have produced promising results but transient models are affected by the highly nonlinear unsaturated zone dynamics and parameter uncertainties. A medium scale groundwater transport model has been analysed for the catchment Rastatt-Danziger Strasse. In a final stage, a model covering the entire city area was set up and used for scenario simulation.
In Doncaster, MODFLOW and the solute transport module MT3D were employed. The groundwater flow model was derived from the regional water resources management model established in 1993 (Brown and Rushton 1993), extended and slightly modified in 1997 (Shepley 2000). It was refined and transcribed to meet the AISUWRS requirements and subsequently used for scenario simulation.
A very similar approach was followed in Ljubljana where the Groundwater Vistas package was used for pre- and postprocessing of the MODFLOW model.
In Mt Gambier, due to the complex nature of the fractured aquifer, a different analysis model was required. This model is based on an integrated assessment based on a Hazard Analysis and Critical Control Points (HACCP) framework. Initially, the substances in stormwater are identified and the likely concentrations and attenuation mechanisms of potential contaminants are examined. This allows the concentration of each contaminant to be calculated, taking into account the attenuation possible within a given travel or residence time. Comparison of the calculated concentration (allowing for attenuation) with the guideline or trigger value indicates the risk of pollution. However, estimates of residence time
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 22 within the karstic Gambier Limestone vary from months, in the fissures, to thousands of years, within the matrix. Thus, an integral part of this work relies on the application of geochemical tracers to determine the actual residence time of contaminants within the aquifer, which in turn has a large impact on the extent to which the aquifer’s attenuation capacity can be relied upon for protecting the city’s future water supplies (Vanderzalm, et al., 2004).
The results of the groundwater modelling exercises are detailed in the case study chapters.
2.1.8 Socio- Economic Assessment GKW/Futuretec
The Socio-Economic Assessment will best be achieved by considering the interests of the main stakeholders as well as their different perspectives on the urban water system. Some stakeholders have a direct involvement in decision making on water production and use, as for example: • Public water producers and owners of public installations: Utilities, Municipal Council, and Municipality • Water producers and consumers with or without private disposal and irrigation: Businesses (here defined as all kinds of activities and employments, regardless of private or public ownership), and large land owners • Water consumers: Private households and businesses. Some other stakeholders are indirectly involved as consultants, lobbyist, politicians etc.: • Parts of the municipal administration • Business Associations, Labour Unions, R&D or Engineering companies • Surveying institutions, political parties, and land owners’ associations These stakeholders have different perspectives looking on the water system, and considering the impacts on the environment, the social situation, and the economy. In order to come to a practical assessment, a set of indicators has been developed and applied in the project. This socio-economic analysis does not intend to analyse all urban problems. The analysis strictly centres around aspects under consideration within the AISUWRS approach (as e.g. leakage from urban waste water systems) and the models developed within the project. The analysis primarily considers the water system as a black box that interacts with the “Urban System”. In this context the Urban System consists of water users (as e.g. private households and businesses), people with their way of life (e.g. consumption pattern), urban settlements, architectural constructions, traffic and businesses of different kinds that give employment and wealth to the population. (Business is here defined as all kinds of activities and employments, regardless of private or public ownership, including: Farmers, Public services for swimming pools, beaches, sport arenas, parks & gardens, Public Administrations, Industries etc.).
The AISUWRS Socio-Economic analysis supports the final assessment and decision making by proposing a methodological approach, computer based tools (the SEESAW Model and the AISUWRS Deliberator Cube), practical guidelines, and reports and examples from the pilot cities. The Methodology of the S-E Analysis proposes several steps which were applied within the AISUWRS project: Step 1 Questionnaire survey among private households Questionnaire survey to gather a general estimation of citizens (private households) and their willingness to pay for changes in the water system, quality and quantity. Under some circumstances it might be appropriate not to seek for a random sample questionnaire survey but rather a certain amount of individual interviews with experts. Step 2 Interviews with stakeholders Interviews with stakeholders to disseminate information about the decision situation and the socio- economic indicators and to gather the stakeholders’ assessment of the action scenarios well before the final decision meeting. Right from the beginning the local AISUWRS project partner selects the most important stakeholders of the urban water system using the systematic stakeholder scheme. Then he will ask each stakeholder for an interview of 1 to 2 hours. Step 3 Analysis of Citizen Appreciation Analysis of the questionnaires (from the random sample of citizens) and analysis of the stakeholder interview results producing statistical data on needs, importance, and payability. As some of the stakeholders might be considered of being experts in water systems and sustainability they will be asked to fill an expert questionnaire. The SEESAW Model is an analytical tool also designed for the purpose of socio-economic analysis of the urban water system. Once the questionnaire data is entered, the SEESAW Model will produce
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 23 results for the further use in the project. Step 4 Socio-Economic-Environmental assessment of the actual situation and the proposed Action Scenarios. Methodological assessment of the actual situation and the proposed action scenarios to produce decision support information, especially a comprehensive explanation of the decision situation for the target group stakeholders and a set of socio-economic-environmental indicators. The Socio-Economic-Environmental analysis using the SEESAW Model combines all data collected and evaluated within the previous steps. Step 5 stakeholder workshop for assessment and discussion Support of the decision making process by moderation of one or more workshops for assessment and discussion. This process will be supported by the AISUWRS Deliberator, a special tool to explain the action scenarios’ assessments of different stakeholders considering the relevant decision criteria in a three dimensional cube.
2.1.9 Sustainability Analysis GKW/Futuretec
Within the project, an AISUWRS Urban Water Sustainability Analysis assessment approach and an associated tool, the SEESAW model, have been developed. The approach aims to support environmental researchers and engineers in defining future actions and to help municipalities in understanding the complex situation within an urban water system, providing them with a simplified approach for its further decision making. The AISUWRS Urban Water Sustainability Analysis uses two perspectives: A scientific-technological perspective with focusing on environmental and technical aspects of the urban water system and potential improvement measures - and a socio-economic perspective which considers the interrelations between the urban water system and society, economy and their environmental implications. The analysis centres around aspects under consideration within the AISUWRS approach (as e.g. leakage from urban waste water systems) and the models developed within the project.
The AISUWRS approach aims to integrate the difficult definition or selection of action scenarios by an iterative process within a community or water utility. A scheme has been developed including the necessary steps for decision making showing the actions of the stakeholders involved: the urban water flows and sustainability of the present situation is to be analysed by academic research institutes and consultants, who furthermore test the impact of action scenarios using the AISUWRS urban water modelling chain. The water utilities jointly with engineering consultants are involved in the assessment of the water supply system and they define necessary or alternative action scenarios. These scenarios are tested on one side by application of the AISUWRS model chain onto their physical effects to groundwater, on the other side with regard to the investment involved. The final decision making by the water utility or municipality considers the socio-economic impact as e.g. social needs, importance and payability. The AISUWRS approach supports this process by the analysis of the citizen appreciation via information gained from surveys and interviews and by application of a deliberation matrix during the decision process.
The computer based SEESAW Model incorporates questionnaires as well as evaluation files for the different parts during the analysis. The analysis of the environmental and technical perspective by the SEESAW tool is based on information on the water utility’s technical system including drinking water supply, public water consumption and the waste water services and completed by information via modelling results on the groundwater situation including water quality and quantity. The model assists in computing indicators related to the water cycle in an urban system and aims to the definition of action scenarios for long term sustainability of the water system. The completion with socio-economic information is conducted via a questionnaire survey among private households with regard to their valuation of the situation and the action scenarios as well as their willingness to pay for improvements; interviews with stakeholders to disseminate information about the decision situation and the socio- economic indicators and to gather the stakeholders’ assessment of the action scenarios well before the final decision meeting; support of the decision making process by moderation of workshops for assessment and discussion supported by the AISUWRS Deliberator, a special tool to explain the action scenarios’ valuation of different stakeholders considering the relevant decision criteria in a three dimensional cube with the dimensions “Stakeholders”, “Actions”, and “Decision Criteria”..
The SEESAW Model, being an Excel-application, is available in English and German, other languages may be added via language tables. The SEESAW Model consists of Input-Forms with regard to the city related basic input, the situation from point of view of the water utility and groundwater modellers,
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 24 the action scenario description, the questionnaires to private households, experts and businesses etc.; Service tables such as language tables, scenario administration files and statistical analysis files for the questionnaire analysis; Output Forms including evaluation sheets acting as reporting tables. They report e.g. on the assessment of the actual urban water situation from a technical point of view on consequences to the action scenarios, on the expectations and valuations of water users compared to the action scenario improvements, on new water prices related to improvement measure implementation etc.
The SEESAW Model has been adopted according to findings and difficulties encountered during the project.
The SEESAW Model has, as far as possible, been applied to the four AISUWRS case study cities of Ljubljana, Slovenia, of Mount Gambier, South Australia, of Rastatt, Germany, and of Doncaster, England. Unfortunately not the whole intended scope of the approach could be implemented, applied and approved during the project: data availability was scarce due to either sensitivity problems with regard to commercial water utilities (Doncaster), non-existence of data in the case study city’s utility (Ljubljana) or similar problems. The decision orientation of the approach was partly confronted with political constraints related to the action scenarios defined for model application (Rastatt). And the final decision workshop in the four case study cities was not applicable, as on one side for all the cities the action scenarios were found to be not relevant for actual decision making, and on the other side, results with regard to the impact of improvement measures were delayed and thus caused further delays for the subsequent workshops that could thus not be planned as early in advance to win the stakeholders for participation. Thus, the AISUWRS deliberation matrix could not be applied. However, in all four case study cities the analysis could partly or by adding some literature research values be carried out to a certain extent. The application and its results are summarized in chapters 2.2.1.4, 2.2.2.4, 2.2.3.4 and 2.2.4.4
2.2 Case Studies
2.2.1 Rastatt
2.2.1.1 Background
The city of Rastatt has been chosen as a case study for the AISUWRS project also for the good availability of data and existing background knowledge on the local hydrochemistry. With respect to the complementarity of case studies, Rastatt is the only city which has a porous aquifer system with exclusively matrix flow phenomena. The aquifer is comprised of unconsolidated sand and gravel sediments of quaternary age. Some intercalations of silt and clay sediments are present but form only locally effective barriers. Similar aquifer settings are common for major cities world wide which have often developed upon young alluvial plains. Rastatt is located in the Southwest of Germany in the eastern part of the Upper Rhine Valley, approx. 25 km south of Karlsruhe. It is bordered by the River Rhine in the West and the foothills of the Black Forrest in the East. The mean annual temperature is 10°C, mean annual precipitation is between 850 mm/m3 and 1000 mm/m3. Rastatt has a longstanding tradition emerging from medieval settlements in the 11th century and has nowadays approx. 46 000 inhabitants. The drinking water supply of Rastatt is exclusively from groundwater with the main waterworks situated upstream of the city. However, the groundwater downstream of Rastatt is used for the drinking water supply of Karlsruhe with approx. 300000 inhabitants. The outlier protection zone of the Karlsruhe water works reaches the northern part of the Rastatt city area. A concise compilation of background information is provided in deliverable D2 of the AISUWRS project (Eiswirth et al 2003). A comparative overview of the different case studies is available as deliverable D3.
2.2.1.2 Field studies
Within the experimental field investigations new hydrochemical evidence for exfiltration from leaky sewers was found. The placement of focus observation wells in the direct vicinity of defect sewers using the geographically referenced sewer defect database provided opportunities for direct observation of sewage influenced groundwater. Online probes which monitored physico-chemical
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 25 characteristics detected daily variations in specific electrical conductivity of groundwater in the focus observation wells. The comparison with the city-wide sampling campaign showed elevated concentrations of most parameters (including sodium, potassium, boron, phosphorous and ammonium) in wells close to defect sewers. The microbiological sampling programme comprised Escherichia coli, total coliforms, enterococci, faecal streptococci, sulphate reducing clostridia, Clostridia perfringens, coliphage and Pseudomonas aeroginosa. Indicators of faecal contamination have been found in several groundwater samples. The groundwater from 6 out of 12 wells is not suitable for human consumption according to german and international drinking water guidelines. However no correlation between leak geometry, distance to the leak and microbiological indicators was found. In addition the correlation between other wastewater indicators (e.g. ammonium, boron, pharmaceutics) and microbiological indicators was very weak. The findings of Escherichia coli in well D1 support the idea of a defect house branch connection as an additional sewage source. It must be stated that wastewater in Rastatt contains high numbers of all the organisms screened for but removal of several magnitudes is taking place within the sediments surrounding the sewer. Nevertheless, some of the bacteria and viruses pass the natural barrier and continue to pose a threat to human health. The screening for pharmaceutical residues in groundwater and sewage samples revealed the existences of betablockers (Metoprolol, Sotalol) in the urban groundwater. Compared to the state-wide survey undertaken by the LfU (LfU 2002) pharmaceutics have been found with elevated frequency in the Rastatt groundwater samples. These results correspond to other parameters indicating sewer leakage. At the test site Kehler Strasse it can be seen that only limited degradation or attenuation of most pharmaceutics occurs on the 50 cm seepage route. All substances identified in the sewage have also been recorded in the seepage water in a similar concentration range. Ocassionaly, the concentration in the seepage water were above the concentration in the sewage. In order to establish a mass balance in this strongly transient system, a denser monitoring scheme is obviously necessary. The pharmaceutical group of iodated x-ray contrast media received special attention in the sampling programme. 114 samples from 46 wells were analysed and resulted in a total of 51 positive detects of iodated contrast media. The frequency of the positive detects as well as the maximum concentrations exceed the values from the state-wide sampling campaign in Baden-Württemberg (LfU 2002). No x- ray contrast media were found in wells which are within a distance of more than 60 m to the nearest upstream sewer. The occurrence of the iodated x-ray contrast media clearly proves the existence of major amounts of sewage in the urban groundwater. Due to their chemical robustness, iodated x-ray contrast media are well suited as a marker species. However they are not distributed evenly over the city area.
The new sewer test site Rastatt Kehler Strasse was set up in order to monitor exfiltration processes in undisturbed environments under real operating conditions. Water level in the sewer, flow velocity and composition of the sewage and the exfiltration rate from a ca. 30 cm² leak were monitored with a high time resolution over a period of more than 12 months. The experiment can be divided into two phases: • Phase I: During phase I, a cavity which remained from the construction process, was gradually filled with sewer sediments and biofilm material. Exfiltration rates up to 230 l/day were measured after storm events. This situation may be regarded as representative for sewers which are subject to alternating infiltration/exfiltration situations dominated by a seasonally changing groundwater table. During the infiltration period, surrounding sediments are washed into the sewer, leaving behind a void around the leak. If groundwater levels are dropping again, the void is slowly refilled with sewage material. At this stage, very high exfiltration rates, as measured during phase I of the Kehler Strasse experiment, are likely to occur. • Phase II: After six months of continuous operation, the exfiltration rates approached a pseudo- steady state. The exfiltration during dry weather flow amounted to an average of 1,3 l/day and 5 l/day connected to storm events. About 42 % of the total exfiltration volume during the period from January to June 2005 can be attributed to rain events which are affecting the exfiltration rates during 26 % time of the balancing period. Attempts to derive hydraulic conductivities based on sewer water level, leak size and exfiltration volumes resulted in uncertain statements as the correlation between sewer water level and exfiltration rate is quite poor. It is planned to overcome the problem in future with a more precise information on the travel time. A recent investigation using the advanced optical inspection technique PANORAMO has demonstrated that the leak geometry is more complex than anticipated during the construction. A function which links the leak area with the fill levels will have to be introduced. Furthermore, the uneven distribution of the colmation layer along the leak will have to be taken into account. Summarizing it can be stated that the data monitored at the test site Kehler Strasse demonstrate the high complexity and the many factors influencing the colmation process. Chemical analysis conducted on the soil water samples demonstrated high boron concentrations of
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0.2-0.3 mg/l, compared to a natural background of 0.02 mg/l B in Rastatt.
For the assessment of urban recharge, sources in the data acquisition were subdivided into the compartments rainwater, river water, wastewater and drinking water. Up to date measurements of natural groundwater recharge have been obtained from state owned lysimeter stations. The existing calibrated groundwater models were used to extract further information on groundwater recharge.
For the description of the unsaturated zone the existing drilling logs were reviewed and a simplified table was prepared as an input file for the unsaturated flow and transport models.
From the numerical groundwater models as well as from the characteristic behaviour of groundwater levels it can be concluded that the river Murg has a significant influence in quantitative terms on the urban groundwater in Rastatt. The River loses water to the groundwater in the upper part of its passage through Rastatt and is gaining from the groundwater in the lower reaches. According to the calibrated groundwater flow models (Klinger 2003, Kühlers 2000), the infiltration into the groundwater amounts to 19388 m³/d for the immediate city area of Rastatt including Niederbühl. This corresponds to 1,43 % of the long term average flow of the river Murg measured at Rotenfels. If this volume flow is related to the area covered by the UVQ model and other water balance calculations, it would be equivalent to an annual groundwater recharge rate of 679 mm/a. This impact has also been observed during the hydrochemical investigations.
Exfiltration from leaky sewers can be a significant factor in the urban water balance. However, the direct assessment of the exfiltrating volumes based on TV-camera inspections has large uncertainties due to the imprecise knowledge of the input parameters. A set of rules for the calculation of leak sizes from the CCTV-inspection data sets coded according to ATV-M143 was proposed and used for the estimation of the total leak area in the sewer system. Leakage rates from several experiments in the literature were compared with new field measurements in Rastatt. Based on the application of Darcy´s law to the colmation layer an extrapolation to one example catchment as well as to the entire city area was performed. In order to account for the uncertainties in the input parameters, a Monte Carlo Simulation was applied to the data sets. For the sub-catchment Rastatt-Danziger Strasse (0.22 km²), the leak size was included in the Monte Carlo analysis. A probability density function was derived from the simulation of 2000 leaks and applied proportionally to the 262 observed sewer leakages in the catchment area Danziger Strasse. The summed leakage amounts to 5.4 m³/d (1.6 % of the typical dry weather flow of 320 m³/h), equivalent to 8.8 mm/a groundwater recharge from leaky public sewer systems. For the estimation of groundwater recharge from leaky sewers on the city scale (10,4 km²), the leak size was excluded from the Monte Carlo analysis. The calculated probability distribution was applied to the total number of 5295 leaks, resulting in a groundwater recharge rate of 7,41 mm/a for the Rastatt city area. Accounting for an error in the leakage size determination, the groundwater recharge will be between 3,72 mm/a and 13,92 mm/a. The calculated values show a good correlation with the exfiltration rate measurements performed at the test site Kehler Strasse. Overall, the large range of possible exfiltration rates underscores the necessity for groundwater quality monitoring and the use of marker species approaches besides the CCTV-based assessments.
The recharge from leaky drinking water networks has been assessed based on the water network losses calculated by the local water supply company from the difference between supplied and billed water. The losses from the water distribution system have remained between 6 and 13 % during the last 20 years. This results in groundwater recharge rates by the leaky drinking water system between 10.3 mm/a and 17.2 mm/a, which is a significant addition to the 90 mm/a expected for an urban area. Locally, much higher recharge rates may be present due to an increased density of the network. Balance calculations with UVQ based on the assumption of 10 % leakage of the water supplied to a neighbourhood result in groundwater recharge rates up to 72 mm/a.
The intrinsic vulnerability of the groundwater resources in the study area Rastatt was assessed using the GLA as well as the DRASTIC method. The results have been displayed in vulnerability maps which provide support in land use planning. Both vulnerability assessments show the critical areas where potential impacts of pollution may contaminate the groundwater resource the most. The center of the Rastatt urban area is characterised by low to medium vulnerabilities according the GLA-method. However, the most recently developed industrial areas in the eastern part of the town are located in areas of high and very high vulnerability. Further developments in this direction should take special precautions in the handling of potential pollutants. Considering vulnerability assessment with regard to
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 27 leaking sewer pipes the assessment should be corrected in terms of the reduced thickness from impermeable layers and missing soil cover as the origin of the exposure is beneath the surface. Especially for the urban area of Rastatt this would generally result in higher vulnerabilities.
The long term evolution of groundwater levels was assessed based on existing LfU-measurements of groundwater levels starting as early as 1913. Only changes smaller than 1.5 m in groundwater levels have been observed in the area of Rastatt during the last 90 years and show that the anthropogenic impact on groundwater levels in this area has been moderate. This is due to the very productive younger quaternary aquifer, the high recharge rates and the exchange with the surface waters of the Rhine and Murg systems.
2.2.1.3 Model Application
The application of AISUWRS models to the case study Rastatt proceeded in several stages. For the first applications, two small demonstration catchments were selected for assessment of the general feasibility and to allow fast calibration. In a subsequent step the entire city area of Rastatt was modelled. The first demonstration catchment included the sewer-groundwater monitoring site Danziger Strasse with the outlet being a known hydraulic bottleneck of the combined sewer system in Rastatt. Selected results are documented in (Klinger & Wolf, 2004). The second catchment is situated upstream of the newly constructed sewer test site Kehler Strasse. At this site, the water balance has been modelled with UVQ for the year 2003 and could be well adjusted with regard to both the dry weather discharge and the storm water flow. The contaminant fluxes were modelled by using solely literature values for the input concentrations (for N, P, SS, Cu, Zn, Pb). The comparison of the measured and modelled concentration of the sewage showed conformity within reasonable ranges (Klinger et al., 2005). The test site Kehler Strasse was also used to compare exfiltration rates predicted with the NEIMO model with the measured rates at the sand filled collector box.
After the successful completion of the feasibility studies, the time consuming task of representing the entire city area in the AISUWRS model was started. In order to account for the pronounced spatial variability and the complex set up in a city with several different construction periods, the model domain was divided in 74 neighbourhoods (Figure 2-8). This also corresponds to the maximum number of neighbourhoods which can currently be modelled with UVQ. Based upon GIS-analysis of cadastral information, appropriate numbers of houses and inhabitants were assigned to each neighbourhood and the surface area was divided into the four categories of public open space, road, roof and garden areas. Where necessary, the information was supplemented by direct field visits.
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Figure 2-8: Distribution of groundwater recharge along the 74 neighbourhood. Calculated from the combined results of UVQ and NEIMO.
The preparation of the necessary input data for the Network Exfiltration and Infiltration Model (NEIMO) was achieved in cooperation with the City of Rastatt which supplied geopraphical referenced information about the sewer system. Among the AISUWRS case studies, Rastatt is the only city with an almost complete coverage of CCTV information of the sewer network. This condition information was given spatial reference and based on generic asssumptions the defect sizes per asset were estimated from the CCTV records. This condition information shows significantly smaller defect sizes and frequencies than the generic defect curves which have been developed in Melbourne and applied to the other case study cities. The quantitative estimation of the exilftration rate per asset for the baseline scenario using CCTV information is shown in Figure 2-9.
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Figure 2-9: Exfiltration from the wastewater sewer network in Rastatt as modelled with NEIMO based on CCTV data.
For the analysis of the protective function of the unsaturated zone, the UL_Flow and the UL_Flow_UVQ flow model were applied to the Rastatt case study as detailed in chapter 2.1.5.
The groundwater model was realised using the finite element code FEFLOW 5.2 from WASY. A three- dimensional steady state model covering ca. 88 km² was set up using a discretisaton of 155 460 elements. It consists of five layers representing the upper Quatenary aquifer (the first three representing the upper gravel layer, the fourth the upper interlayer, the fifth the middle gravel layer). They add up to a thickness of between 10 and 40 m and are based on the interpretation of borehole data. The model was calibrated to fit the typcial climatic mean situation of 20.10.1986 using inverse parameter estimation (PEST) with manual control.
The scenarios modelled in Rastatt comprise:
• Baseline scenario • Sewer rehabilitation scenario • Increased rainwater infiltration scenario • Climate change scenario • Population/demand change scenario
All scenarios have been modeled both with CCTV data as well as with the generic defect assumption concerning the sewer condition. While it is technically feasible to model time series of 30 years with the AISUWRS DSS, a different strategy for the handling of time transient data had to be adopted due to the large computational effort. Out of the available 30 year climatic data sets, from 1960-1990 and from 2070-2100, representative years with a climatic water balance close to the long term average were selected.
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Case study Rastatt Evapotranspiration Precipitation Average climatic condition 1960-1990 322 Imported water Scenario: Baseline 1091 202 Legend 547 545
Rain/Tap water 201 157 189 Change in Leakage Stormwater storage Outdoor 53 water use 19 15 18 6 Wastewater 269 Road Roof Paved 3 Groundwater 178 19 15 18 Pervious Input 51 soil store Indoor 163 127 153 water use Output Recharge 20 347 5.7 443 Flow path Surface runoff Groundwater Wastewater Water store generated generated 142 Urban area 3.9 178 Stormwater 301 Annual depth sewer Combined sewer 15 of water (mm)
142 483
Total discharge 629
Figure 2-10: Water balance diagram for Rastatt using a typical year selected from the modelled climatic data series 1960-1990.
The results obtained from the modelling exercise are detailed in appropriate chapter of the IWA book, A holistic water balance diagram for a year with climatic conditions typical for the period 1960-1990 is shown in Figure 2-10. The modeled infiltration scenario demonstrated the a large potential for the uncoupling of sealed surfaces from the sewer system exists. The hydraulic loading of the system could be reduced significantly. The dominant sand and gravel sediments allow rather simple technical measures for the infiltration. Nevertheless, the socio-economic studies have shown that rather high costs are associated with the proposed decentralized infiltration measures as they affect already existing housing stock. With the use of the groundwater model it was shown that the groundwater levels are almost not affected. This is in contrast to an example calculated by Göbel et al (2004) but can be explained by the high hydraulic conductivites and the different aquifer setting. From a water quality aspect, the additional load of heavy metals like zinc and copper to the soils in the neighbourhood was modelled.
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Boron (mg/l) CCTV- Generic Observation Well Measured defects Defects Rehabilitation 0134-211-1 0,023 0,024 0,024 0,024 BK1-119 0,035 0,024 0,024 0,024 Hasenwaeldchen 0,042 0,024 0,031 0,024 0156-211-1 0,061 0,029 0,028 0,024 0154-211-2 0,043 0,029 0,060 0,024
. Figure 2-11: Modelled concentration of boron in groundwater of the upper gravel layer in Rastatt after implementation of the DSS results with CCTV data in the baseline scenario.
With regards to the sewer network the modelling exercise demonstrated the load to the aquifer and the rise in the concentration of key marker species in the groundwater body. However, the groundwater concentrations predicted by the modelling suite generally seem to be below the measured concentrations at the monitoring wells. This points either towards the existence of additional sources for the considered component, the strong influence of leaky house connections (which are not considered in NEIMO) or towards an incorrect estimation of the sewer condition using CCTV. In addition it must be considered that the AISUWRS modelling suite is averaging over neighbourhood with dimensions of several hundreds of meters while the monitoring wells might be strongly affected by an individual leak close by. The climate change scenario relied on predictions of the Danish Meterologial Institute for the time period 2071-2100. The main deviations to the current climatic conditions are increased rainfall in winter, decreased precipitation in summer, overall increased evaopartion and decreased groundwater recharge. The modelled impact on groundwater levels within the city area alone is low, however larger regional models are required to adequately describe the effects of this regional phenomena which lead to changed boundary conditions. As also the frequency of extreme rain events is expected to rise, it is recommended to invest in decentralised infiltration measures as a relief to the sewer network.
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2.2.1.4 Socio Economic Aspects and Sustainability Analysis
With regard to the urban groundwater resources, the sustainability indicators present a positive picture for Rastatt: overall groundwater levels have been stable during the last two decades and Rastatt’s groundwater quality corresponds to the WHO drinking water guideline values - however, certain chemical parameters have increased locally, leading to a tren contrary to the EU water framework directive (aiming to protect uncontaminated groundwater sources, avoid further contamination and improve already contaminated sites). Protection and public awareness is assumed to be of a relatively high standard. The water utility in Rastatt produces approximately 64 to 65% of the total societal water demand and 99 % of the population is connected to the water supply. Private abstraction is mainly done by major industry. The utility’s water production slightly decreased since 1990. More than 90 % of the water produced during the last 20 years went into consumption, and less water is wasted during production and transport in recent times. Throughout the last two decades, the energy efficiency of the production process stayed constant with 3 m³ production per kWh and the annual per capita energy consumption for treatment decreased as production decreased. Water losses in the network system have stayed below 10% and show a very positive trend to 4% in recent years. This leaves a generally good picture of the water supply services. Wastewater treatment effectiveness with regard to BOD has been constant with 98 - 99% being typical for biological treatment plants. Effectiveness in N and P treatment could be increased from 1990 to 2004. The absolute loads that entered the ecosystem after treatment however strongly increased for BOD, while nitrogen and phosphorous loads to the receiving water bodies decreased. Over the last two decades, less energy has been needed to reduce one kg of BOD, N and P load. The annual per capita consumption of chemicals and energy[contradicts previous sentence] has however increased since 1990, resulting in scale effects. Energy recovery from biogas is taking place, Ecosan concepts are so far not under consideration. Rastatt does not so far face a major problem with regard to groundwater, water supply, consumption or wastewater services. The scenarios have been found to be not relevant for the decision makers, they were calculated in order to approve the application of the AISUWRS computer tool in Rastatt. The socio-economic analysis shows the assessment of the public (private household survey) and of some stakeholders. It can be summarised by the following Quality-Importance-Matrix containing the 26 relevant indicators:
Importance
t n a t t r t t n o n n a p t a a r t t r im r o t o l o p Improvement is l p n p a a t im t m r im i possible / a o e t y t le p i r t o t u e desirable Quality n li im q v no very good C D
B E M N O little good A I L XYZ
F J K Q R yes improvable G P S T U VW strongly bad H very strongly very bad
Where the letters stand for the following indicators: Water quality A Chemical Ingredients B Quality summarized Water quantity C Available quantity drinking water D Availability to all customers
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Water Production Effectiveness E Water authority F Rainwater collection G Private wells H Recycled water Assurance of future supply I Ground water reserves J Safety from industrial damages K Prevent infiltration of chemicals L Active water quality monitoring Quality of life M Spas, sport and entertainment (with water) N Design of water features and landscapes O Secure water levels for buildings, streets, channels etc. P Water for satisfactory hygiene Protection against flood damage Q Protection against backpressure & submerged sewers R Protection / Defence against flooding S Rise of groundwater level / wet cellars Prevention against environmental factors T Pollution of groundwater U Pollution of rivers and lakes V Pollution of soil W Drop in groundwater level Water as business factor X Attractiveness of the city for businesses Y Attractiveness of the city for tourism Z Service and efficiency of water supply
Although there is a high sensitivity towards water related issues, only few indicators are judged as being bad and important at the same time. Only the use of recycled water would be ranked high in the priority list of the private households. But this opinion differs from expert opinions, which would see the need for more protection against backpressure & submerged sewers. Summarizing it can be stated that the sustainability analysis has considered a wide spectrum of socio- economic-environmental indicators. They point out some only slightly critical aspects.
2.2.2 Doncaster
2.2.2.1 Background
The Doncaster case study concerns the Sherwood Sandstone aquifer, which is the second most important in the UK after the Chalk. This regionally extensive sandstone formation is part of a more widespread Permo-Triassic Bunter and Lower Keuper red-bed sandstone sequence which also forms productive aquifers elsewhere in northwestern Europe. In eastern England, it outcrops in a structurally
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 34 controlled arc from south of Nottingham to the North Sea at Hartlepool, Co. Durham. Doncaster is groundwater-dependent, and the city’s nearby former mining villages and a large rural hinterland are supplied from a network of boreholes. The piped water supply for the town of Doncaster, its suburbs and surrounding rural area is supplied by the Doncaster wellfield, a linked array of eleven pumping stations extending from just to the east of the town along a 15 km arc to the northeast and southeast. This wellfield supplies about 65 Ml/d to the Doncaster area, with water from four of the pumping stations being blended at the Nutwell Water Treatment Works to supply Bessacarr-Cantley. Doncaster, with a present-day population of about 200,000, is an old-established town on the River Don whose expansion accelerated during the early part of the 20th century into a traditional base of manufacturing, especially light and heavy engineering, glass making and textiles. It has also been closely associated with deep mining from the South Yorkshire coalfield, again from the early 1900s. For some years the town has been undergoing a transition and diversification away from this traditional manufacturing base into different economic sectors, with a notable increase in service industries. These changes led to considerable fluctuations of groundwater tables in and around town. These changes are observed by the environment agency to control a) water levels in urbanised areas where too shallow water tables may lead to flooding of housing basements; and b) water levels near the protected wetlands located in the north east of town. Contaminant levels in the local rural area are relatively low with occasional detects of heavy metals or organic compounds. High nitrate concentrations levels can however be a problem and water abstracted for public drinking water supply is blended in some cases with older water, which has not yet been affected by recent recharge. The complex partial cover of Quaternary deposits of variable permeability (lacustrine clays to fluvioglacial sands and gravels) can also lead to anoxic conditions such that in some areas dissolved iron and manganese occur and need to be removed. Mine drainage of Carboniferous strata that underlie the aquifer during the days of coal mining in the 20th century adds to the picture. Thus the water quality background for the sandstone aquifer that supplies Doncaster is not a simple one; a broadly high-quality raw water (in comparison to its surface water counterparts) has natural water quality constraints in some areas, problems arising from present and past agricultural practices in others and a historical pollution legacy from minewater drainage practices. To this setting is added the additional loadings that occur as a result of urban activities. .
2.2.2.2 Field studies UNIS/BGS
The field investigations complemented the collection and analysis of existing data, particularly by obtaining detailed information about groundwater flow conditions and the urban water mass balance fluxes in and around the study area. This better understanding was used to calibrate the models and to provide a solid basis for the alternative water use scenarios. The field investigation programme comprised: Site selection, drilling, installation and subsequent monitoring of 5 multilevel borehole sites located in Bessacarr-Cantley. The 5 sites sampled up to 7 different depth intervals each in the shallow aquifer down to about 60 m. below ground level. Their design permitted pumped water samples to be taken and also continuous water level and electrical conductivity measurement using programmable in-well data loggers (Rueedi and Cronin, 2003). Multilevel boreholes are particularly useful for detailed groundwater quality studies because contaminant concentrations in bedded deposits can vary markedly in the vertical direction. Sampling of groundwater in Bessacarr (the 5 multilevel sites) and selected existing private wells in the surrounding periurban and rural areas (5 boreholes, reduced from an initial network of 12). Assessment of water quality in the pipe network, comprising sampling at 3 sewer inspection manholes and 2 stormwater outfalls plus the collation of mains water quality data provided by Yorkshire Water. A wide range of microbiological and hydrochemical parameters were sampled and analysed in order to characterise shallow groundwater beneath the study area, periurban groundwater in the surrounding rural area and urban groundwater in the city proper. These data provided background concentrations and contaminant loads used to calibrate the UVQ and the groundwater models. The following summary is an interpretation of results drawn jointly from the available data analyses and from the field investigations. More details are provided in 8 papers published in project field investigations final report CR/05/028N (Morris et al. 2005) and available to download from the
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 35
AISUWRS website http://www.urbanwater.de/ (see numbered reference set at end of chapter). Objective 1. Describe vertical variations in lithology, structure and vertical hydraulic gradients in the aquifer New information from both drilling logs and cores from the 5 dedicated multilevel piezometers showed that the local sandstone aquifer is unstable or weakly cemented to depths up to 30m. This contrasts with other regions where the Triassic sandstone is moderately to well-cemented (e.g. Birmingham, Nottingham), and fracture-flow acknowledged to be important. It is assumed that the vertical hydraulic gradients strongly depend on the long-term pumping regime at the public water supply wells located down-stream of the focus study area. Overall, the downward gradients at the multilevel wells indicate that, as expected, Bessacarr-Cantley is located in the recharge area of the aquifer. Objective 2. Detail the distribution and persistence of standard sewage indicators and sewage derived viruses and their seasonal fluctuations Concentrations of microbial sewage indicators (bacterial as well as viral indicators) and pathogenic viruses in sewage were found to vary over several orders of magnitude, both on a daily and an annual time-scale (Rueedi et al. 2005). This has to be considered when using them to assess quantitatively the influence of sewage on microbial groundwater quality. Chemical parameters were found to vary significantly on a daily time-scale in the sewer but the quarterly sampling suggests the variation may be less on an annual time-scale. The largest frequency of positive detects of the bacterial faecal indicators, and to a lesser extent the enteric viruses, were found in the shallow intervals (0-30m) of the multilevel wells where the largest sewage contributions to recharge were estimated from the major and minor ion mass balance calculations (Rueedi et al., in review). Interestingly, indicator micro-organisms as well as enteric viruses were also found at depths of up to 60mbgl. This suggests deep penetration of modern (<50 year old) water. The occurrence of faecal indicators in Doncaster corresponds with the profiles of the groundwater dating tracers CFC-11, CFC-12 and SF6 (Morris et al. In press) and is consistent with the synchronous seasonal changes noted by pressure transducer readings in the multilevels down to 60 m depth. Objective 3: Assess relative magnitude of sources of urban groundwater recharge and their effects on the quality and availability of water for public and private supply Mains leakage was estimated from Yorkshire Water hourly night time flow records 1998-2003. Leakage rates of the 6 leakage control zones ranged from 1.1 to 5.3 l/property/h corresponding to an average leakage rate of 9.7% of all imported water or 22±5 mm/y equivalent recharge. Current leakage rates from the sewerage system were deduced using mass balance calculations to be about 20 to 45 mm/y equivalent recharge corresponding to a total leakage of 7-15% of annual sewage throughput (Rueedi et al. submitted). Such values are of similar order to previously-reported sewer volume losses (typically 3 to 5%). The use of pollution indicators proved more difficult than anticipated because species that have been demonstrated as useful elsewhere, such as chloride, nitrate and sulphate, show little more variation than that encountered in neighbouring rural catchments. Although the range of indicators used was confined to inorganic and microbiological markers, it suggests that in hydrochemical and microbiological terms, the adverse effect of urban recharge on the measured quality parameters of the underlying groundwater in the Bessacarr-Cantley area has so far been limited. This is ascribed to the combined effects of a non-industrial prior land-use history, locally high storage capacity in the friable upper aquifer and particularly the availability and ready infiltration of dilution from precipitation entering urban green space areas. Monitoring of the multilevels provided detailed depth profiles of various groundwater parameters. Profiles were found to be quite site-specific. This prevented simple comparisons but detailed analysis showed broad similarities that enabled an approximate distinction of likely contamination sources. The urban tracers proving most useful to quantitatively assess urban recharge were potassium, sodium, boron, and bicarbonate. The most useful qualitative tracers were the δ13C ratios, the faecal indicators sulphite reducing clostridia (SRC) and faecal streptococci as well as CFCs and SF6. These demonstrated clear contaminant influence on profiles 0-30m, with some influence detectable to at least 60m, but also showed that the rural background is often as high as the urban loading.
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2.2.2.3 Model Application UNIS/BGS
A set of possible scenarios was discussed with key stakeholders (Environment Agency and Yorkshire Water) and 4 major ones were the selected to be modelled by the AISUWRS model chain (see highlighted grey areas in Table 2-1. These are representative scenarios devised to qualitatively illustrate the effect on the underlying aquifer of changes that are outside the immediate control of local stakeholders, such as climate change or national trends of changing demand (exogenous effects) and those brought about by engineering or regulatory interventions, such as pipe renovation or better use of roof runoff Table 2-1 Scenarios modelled with the AISUWRS model.
Exogenous effects Climate change Demand change Action Scenario Scenario description 2020 2080 Alpha Gamma (likely (Worst 2025 2025 case) case) (likely (best case) case) 0 Actual situation 1 Base case 2A 2B 3A 3B A Sewer rehabili- A All sewers in pre- tation 1945 areas renovated B Reuse of water B1 Roof runoff for (by 100% of garden watering households) B2 Roof runoff for garden watering & toilet flush B3 Grey water from bath/laundry for toilet flush
The first model UVQ (urban volume and quality model) requires a wide range of input data to physically characterise each neighbourhood. Due to the large amount of information required to populate and calibrate the UVQ model, UVQ was set up systematically in a step by step mode. This included abundant data processing and model testing (see Rueedi & Cronin, 2005 for more details). Overall, the model was calibrated to match the available data which included existing datasets and newly measured ones during the field campaigns but as well a series of literature values. The second model, PLM/NEIMO (pipe leakage model), was set up and applied to estimate sewer leakage from each pipe in the system. Raw data required for this model came from a number of datasets. These were used with ArcView to construct the four input files required for each pipe network type used in the model including detailed information on pipe assets (e.g. length, diameter, material, joints, etc.), the number of household connections and the physical upstream/downstream relationship. A number of manual corrections were required to generate these files because the sewer network in Bessacarr-Cantley, which has evolved over >80 years, does not fit the tree-structure assumption. This is probably a common occurrence in European cities, and the compilation of this file gave the most tedious problems (e.g. missing entries, ring pipes, etc.). As there were no field leakage measurements available to calibrate the NEIMO model to actual observations, the model was adapted to obtain the recharge concentrations observed in shallow groundwater i.e. leakage was adjusted to provide enough contaminant load to give observed shallow groundwater concentrations. This may be a way of calibrating the model in areas where no detailed observations of pipeline leakage are available, as is the case in most urban areas. The total leakage volume is about 10% of the annual flow or related to the length of pipes: 1910 m3/km/year or about 0.06 L/km/sec. Note that the resulting volumes for leakage have significant uncertainty. Nevertheless, the exercise was able to incorporate leakage in a semi-quantitative sense and thereby to successfully demonstrate model linkage In reality the leakage (or, more precisely, the extra loadings) could originate from other locations in the
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 37 wastewater removal system such as from house-to-street connections or from sewage overflows after sever storm events, neither of which are considered in the model chain. Another possibility is that current set of generic curves systematically underestimates the crack losses. The next model, the unsaturated flow model (ULFlow), was applied in the case study to assess both average and minimal residence times of water in the unsaturated zone. The latter could be used as an indicator for the local risk of contaminating groundwater. The model requires soil properties and depth of the unsaturated zone for each neighbourhood, and in effect the soil zone thickness is equated to that of the unsaturated zone. Soil properties were taken from the local soil properties data provided by the National Soil Resources Institute NSRI and include spatial information on different lithologies, soil textures and corresponding parameters of water transport. The depth of the unsaturated zone was calculated by GIS analysis using the ground elevation from the NextMap© digital terrain dataset and the water table surface, compiled from the project’s own research boreholes supplemented by Environment Agency regional observations. The saturated zone flow and contaminant transport model is the final stage in the model chain and for the Doncaster case study MODFLOW and the solute transport module MT3D were employed. The groundwater flow model was derived from the regional water resources management model established in 1993 (Brown and Rushton 1993), extended and slightly modified in 1997 (Shepley 2000). The original model is regarded as a well-calibrated regional groundwater model that adequately represents aquifer conditions in the Doncaster area. The following stages were undertaken to provide a suitable platform for the modelling of groundwater flow and solute transport in the detailed study area and especially to facilitate the running and comparison of different urban water scenarios: • The original 2-D model was translated into an equivalent 2-D MODFLOW transient model. This process is described in Neumann and Hughes (2003) and included re-discretization from the original nodal mode to a block-centred grid of 1 km by 1 km. • In order to provide higher resolution in the vicinity of Bessacarr-Cantley, the corresponding sub- regional area in the MODFLOW 2-D transient model was re-discretized to produce a 100 m by 100 m grid across the focus study area. • A steady-state version of the transient model was created; this model used 27-year averages of rainfall recharge, urban recharge, pumping volumes, water levels in the Quaternary cover and regional boundary inflows and outflows derived from the original simulation time period 1970-1997. • As a final stage the steady-state unidimensional version was converted into a three-dimensional version by the division of the aquifer into four layers. For scenario comparison purposes, the head distribution was compared with a base case version (see next section) to facilitate comparisons. Head difference contours were produced using the contouring package SurferTM via a spreadsheet file that compared the exported head distribution output files of the particular scenario with the base-case values. The Decision Support System (DSS) permits the various models previously described to be linked in a model chain to produce a simulation of the actual situation. This status quo condition became the base case which is derived from the actual situation as follows: • The UVQ model output run represents the reference year 1997. • The NEIMO model input and output represent the same reference year 1997 and are daily runs incorporating a statistically-derived distribution of daily pluvial drainage flows. • No unsaturated zone model was required as the groundwater model was run to steady-state conditions. • The groundwater flow model was calibrated in transient mode for the years 1970-1997, then a steady state version used to represent equilibrium conditions (see previous section). • The groundwater solute transport model was run in transient mode to represent the evolution of contaminant distribution. The first 70-year stage represents the evolution of aquifer from the late 1920s as it responded to urbanisation, while the second 100-year stage represents a prognosis for the future.
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 38
Figure 2 Urban water balance for the Doncaster base case
The base case was developed to form the actual situation and used as the basis against which the four chosen water and contaminant balance scenarios were compared (Table 2-1). For the base case, the predicted water table contour map was produced, and to facilitate comparison, the equivalent map for each of the other four scenarios is compared to this head distribution as water table difference contours at completion of each flow model run. Each scenario set thus comprises a water balance diagram (as in Figure 2), a water table difference contour map (water table elevation map for the base case scenario), trend graphs for potassium and chloride contaminant indicators for a central location in Bessacaar-Cantley (Haslam Park) and for the closest downgradient borehole of the public supply wellfield (Nutwell 2), and a comments section. These are described in detail in Chapter 4 of the proposed IWA-sponsored AISUWRS book. It should be stressed that while the results of the scenario runs are quantitative in a mechanistic way, insofar as the models employed in this case study have individually been successfully operated and their outputs linked to produce numerically consistent products, the outcomes should only be viewed qualitatively. It was not within the resources available to this project to assess the effects of uncertainty on the final outputs from the model train on what is very much a prototype application. Nevertheless, uncertainty must be an issue in sequentially applied models with so many input fields, some complexly derived, that combine a necessary reliance on available data with only a limited facility to apply dedicated data collection and interpretation for calibration and validation purposes.
2.2.2.4 Socio Economic Aspects and Sustainability Analysis
In Doncaster, annual withdrawal by the utility steadily decreased during the 1990s to abstraction rates of below 70 Ml/day by 2002. Approximately 10 % of the water consumed by Doncaster is imported surface water. Private abstraction could only be coarsely estimated as an additional 13 Ml/day in 2004/2005. Groundwater levels are at shallow depths and abstraction points influence the groundwater flow pattern. Some regions such as the Hatfield Moor suffer from falling groundwater levels. Also the water quality of the groundwater underneath Doncaster is quite variable, a fact ascribed to local confinement by Quaternary superficial sediments or by the Triassic Mudstones to the east, and also to depth stratification. Low concentrations of herbicides and agricultural pesticides have been widely detected showing increasing anthropogenic influence, and nitrates are locally a water
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 39 quality problem, with raw water from some abstractions exceeding the EU Water Quality Guidelines. The utility supplies water to almost 100% of the population. Taking into account water losses of 10- 12% in the network, the water abstracted locally in the Doncaster wellfield accounts for 85% of the estimated societal water demand in Doncaster showing a high effectiveness in meeting the societal demand. Private production is thus minor. Estimated water delivery from outside is in the same range as the reported water losses through leakage and might be used to compensate for the water losses. Efficiency calculations could not be conducted. Being a private company, data availability from Yorkshire Water was limited due to commercial sensitivity. The total annual societal water demand has been estimated to be at approximately 30 Mm³/y in 1997/1998, decreased to approximately. 26 Mm³/y in 2001/2002 and slightly increased again to 28.8 Mm3/y in 2004/2005. For the year 2004/2005 a daily total consumption of 292 l per capita and day could be calculated based on the estimated total societal water demand and domestic per capita demand figures. This would indicate a total domestic consumption of approximately 13 Mm³/y and more than 15 Mm³/y consumption by other non domestic use. Data reliability is mostly questionable and caution has to be taken when drawing conclusions. With regard to waste water services and associated recycling the analysis could not be carried out due to lack of data availability. The socio-economic analysis reflects the assessment of an expert in water and drainage. The following Quality-Importance-Matrix summarizes the assessment of the 26 indicators used (The letters refer to the same indicators shown in chapter 2.2.1.4):
Importance
t n a t t r t t n o n n a p t a a r t t r im r o t o l o p Improvement is l p n p a a t im t m r im i possible / a o e t y t le p i r t o t u e desirable Quality n li im q v A B C D E J no very good K L
M O P Q S little good Z R U V X Y yes improvable N strongly bad very strongly very bad
It can be seen, that as an overall impression the ranking is good and very good. Only the design of water features and landscapes (N) seems to be improvable, but of little importance. As a summary it can be stated that the sustainability analysis has considered a wide spectrum of socio-economic-environmental indicators. They point out some only slightly critical aspects.
2.2.3 Ljubljana
2.2.3.1 Background
Ljubljana, the capital and largest city of the Republic of Slovenia is an important political, cultural and economic centre with a population of 270 000 inhabitants. It is situated in the heart of Slovenia, 298m above sea level, in a broad basin between the Alps and the Adriatic Sea. Ljubljana represents an important crossroads between Mediterranean, Central and South-eastern Europe.
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The Ljubljana basin around the city of Ljubljana is a large tectonic depression, representing a flat area of approximately 300 m a.s.l altitude amongst hilly and mountainous surroundings of up to 1300 m a.s.l. Its northern part constitutes Ljubljansko Polje (“Ljubljana field”), from where most of the city’s water is abstracted. Its southern part constitutes Ljubljansko Barje (“Ljubljana moor”), a marshy area subject to flooding stretching to the south and southwest of the city.
The plain of Ljubljansko Polje is filled by up to 120 m of Pleistocene and Holocene fluvial sediments and drained by the river Sava (of which the Ljubljanica river is a tributary). It is a phreatic aquifer formed of partly conglomerated Pleistocene gravel, deposited on a basement of Palaeozoic clastites (Figure 3-3). Sediments may be loosely bound and pervious, or tight and impervious. No Holocene lacustrine sediments are present here. Low permeability clay layers immediately to the north and to the east of the permocarbonic outcrop of the hill of Rožnik in the west of the city present perched aquifer conditions in a limited area.
Ljubljana is clearly highly (or entirely) dependent on groundwater for public, industrial, agricultural and other water supply. The city presents a rare example of a reliable and high quality water supply being sustained locally with no artificial pre-treatment of water, and limited wastewater treatment. However, the local aquifers, mostly lying under an urban area, are very vulnerable to pollution. Today excessive environmental burdens are present, and the self-regeneration and neutralisation capacities of the groundwater resources are being reached.
2.2.3.2 Field studies
Field studies in Ljubljana incorporate: • Geological and hydrogeological mapping • Groundwater quality sampling for investigation of the influence of urban contaminants on the local aquifer • Vertical profiling of physical water quality parameters in boreholes to improve understanding of local vertical heterogeneity in the aquifer profile • Piezometric monitoring for understanding and modelling aquifer recharge, flow and storage dynamics • Construction and operation of urban lysimeter for analysis of urban infiltration and recharge • Research, organisation and pre-processing of other groundwater quality monitoring data for Ljubljana • Research, organisation and pre-processing of other data for the fulfilment of modelling requirements within the AISUWRS project
The result of old and new data from geological and hydrogeological field studies was a new geological and hydrogeological map of the Ljubjlansko Polje (Ljubljana field) and Ljubljanasko Barje (Ljubljana Marsh) areas in 1:25 000 scale. These maps were used for general vulnerability and risk studies over the whole city area as well as they aided the development of the flow and transport models.
Groundwater quality sampling results indicate that the groundwater of south-western part of Ljubljansko polje aquifer, where the research area is situated, is relatively clean with some exceptions (two observation wells, OP2 and OP3, respectively), where anthropogenic impact on groundwater is noticed. Groundwater is mostly influenced by inflow of salt water from road salting, locally probably also by pipeline leakage of sewage system, what is also evident from microbiological research and boron content. Indicators of faecal contamination (Escherichia coli, total coliforms, enterococchi and Pseudomonas aeroginosa) have been found in some groundwater samples in upper levels of observation wells. On three out of five sampling sites, microbiological parameters exceeded the maximum admissible concentrations (MAC) in drinking water defined with Slovene Ordinance on drinking water. Concentrations of boron are up to 163 µg/L and are mostly found in the upper parts of the observation wells also. Isotopic ratios of δ15Ν, δ18Ο and δD display very complex source of N compounds. Nitrate concentrations exceeded the MAC in groundwater (25 mg/l) at two observation wells (OP2 and OP3, respectively), but the concentrations are still below the MAC of 50 mg/L in drinking water. Two times, in August 2003 and in December 2003, the MAC in groundwater for nitrate was slightly in excess at Vodovodna observation well. OP2 is the only location with considerable amount of phosphate (PO4 is found slightly in excess of the groundwater standard (0.2 mg/L), 0.215 mg/L in March 2004, namely), indicating an influx of septic tank outlets, leakage from the sewage
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 41 system or fertiliser application. Phosphate is accompanied with potassium, which is also a typical constituent of agricultural sewage and urban pollution. Total chromium concentrations exceeded the MAC in groundwater (30 µg/L) at Vodovodna observation well significantly (57.8 µg/L in August 2004, 60.7 µg/L in December 2003, 71.3 µg/L in March 2004 and 53.0 µg/L in August 2004). This sources are from historical Cr(VI) pollution from nearby industry. Transport of Cr(VI) is in the direction towards the south eastern part of water pumping field Hrastje. Chromium levels decrease to significantly below standards before it reaches the water pumping fields at the edge of the city.
Sewage quality data were used for the calibration of the UVQ model and for comparison with groundwater quality data. Generally, the average concentrations of wastewater for Cl, B, K, PO4, NO2, K, Fe and NH4 are higher than observed in groundwater. An exception is the groundwater from two observation wells (OP2 and OP3) with higher concentration of B and Cl in comparison with residential/commercial wastewater. Sr, Ba and Al are also higher in groundwater of these two wells in comparison with wastewaters. The wastewater in Ljubljana contains high numbers of the microorganisms listed above, but an effective removal is taking place within the relatively thick unsaturated zone. The two observation wells that continuously outstand in the means of high concentrations of chemical and microbiological parameters are situated near railway tracks and in a slightly excavated area with an unpaved car park, respectively.
General agreement is, that urban groundwater pollution occurs locally through smaller, more permeable parts of the unsaturated zone, and probably also through groundwater observation objects (observation wells), where from upper polluted horizons, the water could leak and reach the groundwater between borehole walls and its casing (probable situation at the observation wells OP2 and OP3).
Situation is under control for now, but we should be aware that increased quantities of salt water from road salting causes gradually desorption of inorganic pollutants (e.g. heavy metals) and organic pollutants (e.g. PAHs) from the sediment in the unsaturated zone and they could reach the groundwater level in the future.
It has to be pointed out that, during the AISUWRS project, water from pumping wells at the Ljubljansko polje aquifer - in pumping stations Kleče and Hrastje, as well as water from pumping wells of Union brewery indicated no presence of microorganisms and all measured chemical parameters were below maximum admissible concentrations (MAC) in drinking water defined with Slovene Ordinance on drinking water.
A seasonal distribution of major ions and selected trace elements were determined during sampling campaign also. Some data obtained within the AISUWRS project were compiled with historical data collected by the VO-KA water utility to assist this study. The seasonal variations of the anions and cations are related to the influx of fresh water from rainfall. The lowest concentrations are found during the dry periods and the highest during wet periods.
Vertical profiling was performed to enable better understanding of the heterogeneous stratification patterns (occurrence of clay lenses etc.) and to observe seasonal changes in groundwater physical chemistry in the Ljubljansko Polje aquifer. The results clearly exhibit the influence of infiltration of precipitations in first few meters of examined wells. After initial changes of parameters, strong changes were suspected in the lower parts of observation wells also, due to very heterogeneous sediments, but none observed. Probably the method is not sensitive enough. Elevated values of T, EC and DO from vertical profile of one observation well in December 2004 (between 27 and 43m) may result from sewage wastewater inflow into groundwater. EC vertical profiles of another well show elevated values at 35m, what was ascribed to an influx of salt water of unknown source. The source of stratification in the well, which is closest to the river Sava, could results from different seasonal recharge.
An urban lysimeter was constructed and equipped in order to gain a better knowledge on the role and behaviour of the upper unsaturated zone in the alluvial gravel aquifer in the highly urbanized environment. On the basis of borehole core mapping and measurements of soil moisture and capillary pressure we can conclude that the unsaturated zone in the area of Union urban lysimeter is very heterogeneous. Probes with fairly fast reactions to precipitation events indicate fast preferential flow, whereas probes with small reactions indicate slow flow. Isotope analyses identified two important flow
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 42 types - lateral and the vertical flow. Lateral flow has an important role in the protection of groundwater from the Pleistocene alluvial gravel aquifer. However, the role of vertical flow is quite the opposite, because it is the main factor controlling contaminant transport towards the aquifer saturated zone. Hence investigation of the occurrence and frequency of such rapid recharge events represents one of the main topics of the next research phases.
2.2.3.3 Model Application
The AISUWRS test site was selected in the southwestern part of Ljubljansko polje aquifer around the UNION brewery (OP observation wells). The UNION brewery extracts clean groundwater from the lower quaternary aquifer, which is separated from the upper aquifer by clay layers. These layers are spreading toward the northwestern part of the aquifer. The upper aquifer is often chemically and microbiological polluted, most probably because of the urban area.
UVQ requires a wide range of input data to physically characterise each neighbourhood. The data were colected from the literature, other case studies in the AISUWRS project and from own field measurements. According to the UVQ requirements, the modeling area (76 ha) was divided into 19 separate spatial neighbourhoods regarding to the sewer drainage pattern and land-uses. Beside the base line scenario, three action scenarios were selected and set up. Runoff from residential and commercial sealed areas (roof runoff and paved area) was drained into an infiltration basin in order to reduce the quantity of sewage that has to be treated. The second scenario assumes rehabilitation of sewers constructed in year 1965 or before. And the third scenario anticipates replacement of septic tanks by sewers connected to the Ljubljana sewage system.
A dataset of seven text files with detailed information about the sewer system was used for the NEIMO. In Ljubljana case study the generic pipe defects are used as difficulties are present in the utilisation of local CCTV data in the NEIMO application. Difficulties are presented by the lack of circumferential referencing of defects in the CCTV reports and a missing ID system to link reports to the asset database. Model parameters used in NEIMO were similar as in Doncaster case study (DeltaL A (m) 0.015; DeltaL B (m) 0.015; DeltaL C (m) 0.011; DeltaL D (m) 0.006; Mannings N 0.013; K_kracks (m/s) 0.001, K_joints (m/s) 0.0001). With these parameters used, the most leakage occurs through joints (97%) and about 3% through cracks, which is not in agreement with results from Rastatt, where two types of leakage should contribute similarly to the overall leakage. The total leakage volume is about 4% of the annual flow or related to the length of pipes: 1051 m3/km/year or about 0.03 l/km/sec. As no volumetric field leakage measurements are available for Ljubljana case study, the leakage results should be treated with some degree of uncertainty, as they can only be interpreted as a product of mass balance estimates.
From the results of UVQ and NEIMO, a study area water balance for selected scenarios was calculated for the reference year 2003. The strongest influence on quantity of wastewater in the combined system occurs for the infiltration scenario. With infiltration basins installed, the volume of wastewater in the sewer system reduces for 11% in the study area. Other scenarios affect the total wastewater flows to a lesser extent. The groundwater recharge is most affected by a water mains leakage. Leakage from water mains is potable water and represents no threat to the groundwater. The wastewaters from leaky sewer pipes and spillage from septic tanks could be potentially risky to the groundwater. They represent about 15% of total water volume which infiltrates through the unsaturated zone in the study area (Figure 2-12).
Infiltration scenario gives the worse results regarding the groundwater quality, contributing more load than base line scenario, namely 17% N, 12% P and 2% Cl (Table 1). In comparison with base line scenario, the most favourable scenario which has reduced the loads to groundwater (-6% N, -5% P and -2% Ci) is replacement of septic tanks by sewers connected to the Ljubljana sewage system (Table 1). The town of Ljubljana has c. 12000 active septic tanks; therefore its removal would probably improve the quality of groundwater. Sewer rehabilitation scenario predicted that all sewers, constructed in the year 1965 or before, are rehabilitated and the results show minor affect and improvement of the groundwater quality (Table 1). Table 1: Yearly loads (in grams) and increase/decrease of loads regarding to Base case for nitrogen, phosphorus and chloride, which enter the unsaturated zone through urban area of Ljubljana case- study for different scenarios.
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Study area Nitrogen Phosphorus Chloride g/year g/year g/year Base case 4584151 259969 20261779 Infiltration scenario 5185314 312894 20703350 Removal of septic tanks 4331094 247234 19771204 Sewer rehabilitation 4512695 256298 20153478
Increase/decrease of loads regarding to Base case Infiltration scenario 12% 17% 2% Removal of septic tanks -6% -5% -2% Sewer rehabilitation -2% -1% -0.5%
Evapotranspiration Precipitation Case study Ljubljana 240 Imported water Base case 1091 1347
Legend 762 329
Rain/Tap water
226 343 193 Change in Leakage Stormwater soil storage 49 Outdoor water use 15 22 12 16 Wastewater 191 Road Roof Paved 0 Groundwater 1092 16 24 13 Pervious Input 53 soil store Indoor water use Recharge Percolation Output 195 297 168 8 183 Septic disposal Flow path Surface runoff Wastewater Groundwater Water store generated generated 255 660 Urban area 59 1084
Annual depth Combined sewer 15 of water (mm)
1685
Total discharge Figure 2-12: Water balance for Ljubljana case study. For groundwater and contaminant transport Visual ModFlow 4.0 pro was selected. Our decision was based on the fact that Visual MODFLOW Pro (Professional) is an established industry-standard for applications in 3D groundwater flow and contaminant transport modeling and it is wide spread between Slovenian hydrogeologists. Visual MODFLOW Pro seamlessly integrates many powerful features within an easy-to-use graphical user interface. The mathematical engine is based on the finite difference method for solving flow and mass transport equation. We started our modeling approach with the conceptual hydrogeology model. For this purpose we decided to model a wider area than described before. The main reason was that the model boundaries with fixed conditions need to be properly separated from the scenario simultation area in the city centre in order to avoid a suppression of the induced changes.. The selected area for modeling is presented on the Fig.2.2.3.3-1.
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Fig.2.2.3.3-1: Geographical Research Area with model boundary The modelling area is mainly on the geographical unit of Ljubljansko polje, which is limited with the river Sava in the north, with low hills rising above the settlements of Stanežiče, Šentvid, Dravlje and Šiška in the west. In the south, Ljubljansko polje is limited with the area between Šišenski hrib, Rožnik and the Ljubljana Castle. Modeling area is limited to the north and to northeast by the river Sava. In the east, the limit of the modelling area was represented by the eastern part of Zalog. In the west, the limit of modelling coincided with the western border of Ljublajna polje. Only the northern part of the Ljubljansko barje was included in modelling area, somewhere top the brook Mali Graben, while the southern border of the 3D mathematical model area extends in the line from Šišenski hrib to the Ljublajna Castle. The largest and far the most important surface stream in the research area (in the geomorphologic and hydrogeological sense) is given by the river Sava. In the southern part, the river Ljubljanica flows through the area between Rožnik in Šišenski hrib (Prule and Trnovo area), which does not affect the groundwater of modelling area.
According to the hydrogeological conceptual models the following hydrological boundary conditions were set:
Surface recharge:
• recharge 1700 mm/a • evapotranspiration 1100 mm/a
Line recharge:
• for river Sava river boundary was selected and • for representation of piezometric heads on western and eastern part general head boundaries were selected
The River boundary condition is used to simulate the influence of a surface water body on the groundwater flow. Surface water bodies such as rivers, streams, lakes and swamps may either contribute water to the groundwater system, or act as groundwater discharge zones, depending on the hydraulic gradient between the surface water body and the groundwater system. The MODFLOW River Package simulates the surface water/groundwater interaction via a seepage layer separating the surface water body from the groundwater system. The function of the General-Head Boundary (GHB) Package is mathematically similar to that of the River, Drain, and ET Packages. Flow into or out of a
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 45 cell from an external source is provided in proportion to the difference between the head in the cell and the reference head assigned to the external source. The application of this boundary condition is intended to be general, as indicated by its name, but the typical application of this boundary conditions is to represent heads in a model that are influenced by a large surface water body outside the model domain with a known water elevation. The purpose of using this boundary condition is to avoid unnecessarily extending the model domain outward to meet the element influencing the head in the model. As a result, the General Head boundary condition is usually assigned along the outside edges of the model domain.
The decision for selection of GHB instead of Constant Head Boundary (CHB) was based on better management of GHB in the phase of model calibration. The results of groundwater flow modeling are presented on Fig. 2.2.3.3-2:
Fig.2.2.3.3-2: Flow directions and piezometric heads in the model domain The calibration results show that the maximum head error is smaller than 0.5 meters. The maximum calculated velocities in the model domain are between 40 and 60 m/day. These results are matching the observations values from tracer tests. On the basis of flow model the transport model for conservative pollutants was made (Cl-). The pollutant recharge was represented with concentration recharge boundaries in every neighbourhood. For dispersivity, values from a previously conducted tracer test were selected (30 L/m). On the basis of the calculated results we are now able to see that pollution coming from urban area of interest is spreading fast through Ljubljansko polje. The pollution coming from the study area is mainly affecting the southeastern part of Ljubljansko polje, but it seems that the water supply pumping station Hrastje is not affected (Fig. 2.2. 3.3-3). This means that a planned early warning system for groundwater has to take into account the results of the groundwater modeling exercise.
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 46
2.2.3.3-3: Direction of the conservative pollution spreading from studying area through Ljubljansko polje after 730 days for basic scenario. We also took into account the infiltration scenario situation, but we didn’t notice any significant change in the piezometric levels. This doesn’t mean that changes are not present, but rather that the study area is to small to affect the piezometric levels. We have the same situation when we try to judge the affects of infiltration scenario on the conservative pollution spreading. We also have to point out that we didn’t study typical urban area but an area mixed between urban and industry. The neighbourhoods with dominant industry factors have 30 times higher concentration in recharge fluxes than the urban background. So the main impacts on modeling parameters are coming from industry and not from urban area. For this reason we decided to model the impact of pollution on ground water as that entire studying area is an industry area. The results are shown on the Fig. 2.2.3.3-4. It is obvious that the impacts with regard to the concentrations are higher than they are in without industrial use. Still, they are not very high, especially if we compare them to the impacts coming from agriculture.
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 47
2.2.3.3-4: Direction of the conservative pollution spreading from studying area through Ljubljansko polje after 730 days for the case if all studying area is an industrial area. The Ljubljana city plans for the future are to move the industrial area from the city center to the industrial areas on the borders of the city. Also the main problem of Ljubljana city water supply policy is not the urban or industrial impact but the agriculture in surrounding areas around city of Ljubljana. It seems that the urban area has significant smaller impact on the groundwater than agriculture or industry. From this point of view it seems that a sustainable urban development with improved sewer control and standards will produce in next 50 years improvements to groundwater what at the beginning of our study was not expected.
2.2.3.4 Socio Economic Aspects and Sustainability Analysis
It has to be stated that for the Ljubljana assessment, coarse estimates had to be used that result in a restricted reliability of the results. For Ljubljana, the water tables have been rising and falling during the last five years from 2000 to 2004, yet no general decreasing or increasing trend can be seen. Groundwater quality in general is still within the range of acceptability by national and international standards, however there is a trend to increase pressure on the groundwater system at least with regard to certain chemical parameters (e.g. Nitrates). This indicates an adverse development in water quality. With regard to protection, legally binding regulations and procedures exist for most of the problems. However, they are not efficiently implemented due to a lack of regulatory resources, including inspection and monitoring. The utility supplies water with a percentage of consumption to production of 50 to 60% and the excess per capita production decreased during the recent years. However, the utilities production seems to be 152 % (1990), 154% (2000) and 127% (2004) of the actual total societal demand and consumption from the utility’s supplies would cover 82 - 86% of the total societal demand. Almost 100% of the population is connected to the water supply. Overproduction is related to water losses (and
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 48 unaccounted for water), indicated as more than 40% before 2004 and 36% in 2004. In general, these values show a positive trend but at a very high level. A decrease in the per capita consumption of energy for the drinking water production was observed from 1990 to 2004. The per capita water consumption including all domestic and non-domestic consumption decreased during the last 14 years from 367 l/cap/d in 1990 to 282 l/cap/d in 2004. Treatment of wastewater is so far restricted to only primary settlement, and no biological or chemical treatment is in place. Thus, treatment effectiveness is very low, as e.g. BOD effectiveness stays below 10%. The absolute loads that entered the ecosystem after treatment are very high, especially for BOD (9 imillion kg/y) and N (> 1 million kg/y). It has been reported that biological treatment steps will be implemented in 2005. No estimates could be given for sewer exfiltration. In general, the urban water system in Ljubljana shows some problems with regard to water losses and with regard to the reduction of contaminant loads via wastewater treatment. Thus, the influence of sewer exfiltration is assumed to be minor when compared to the general loads entering the water environment at present treatment levels and the scenario “sewer rehabilitation” has therefore not the highest relevance. In Polje, only 70% of the households are covered by piped wastewater services, and loads entering the ecosystem from septic tanks might be considerable, thus the scenario of septic tank connection to the wastewater service and rainwater infiltration. The socio-economic analysis reflects the assessment of a group of experts in water and geology. The following Quality-Importance-Matrix summarizes the assessment of the 26 indicators used:
Importance
t n a t t r t t n o n n a p t a a r t t r im r o t o l o p Improvement is l p n p a a t im t r im im possible / a o e t t le p i ry t o t u e desirable Quality n li im q v no very good C D
B E P Q R little good I S YZ
A J L T yes improvable GM O U X VW strongly bad F H N K very strongly very bad
The expert group comes to a severe assessment: Several indicators are rated as bad or improvable, and as important, quite or very important. The most critical factor is the assurance of future supply by preventing the infiltration of chemicals. But also the recycling of water and the design of water features and landscapes are considered as bad and quite important. Thus it can be stated that no actual problems endanger the water sustainability, but the setting is sensitive to future measures that could ensure sustainability into the future
2.2.4 Mt Gambier
2.2.4.1 Background
Mount Gambier is the Australian case study city for the AISUWRS project. The city represented an excellent opportunity to apply the AISUWRS approach, as the city of Mount Gambier overlies an unconfined karstic Gambier Limestone aquifer, which feeds Blue Lake, the city’s drinking water supply. It represented a unique study site due to the uncertainty associated with flow-paths in the karstic
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 49 aquifer and also as the city’s stormwater and sewage networks are isolated, with stormwater directly discharged into the unconfined aquifer.
The unconfined Gambier Limestone aquifer has characteristics of a dual porosity media with both primarily developed porous medium and secondary developed karstic flow. While the regional groundwater flow direction in the unconfined aquifer is toward the southwest, local flow systems and the karstic domain can reverse this in the urban area. Groundwater flow into the lake is believed to be predominately within the dolomitic Camelback member, also the zone where stormwater is discharged
The modelling of contaminant flow in karstic aquifers is a significant challenge due to the heterogeneous nature of groundwater flows and the potential for contaminants to travel much faster than predicted by standard models based on Darcy’s Law (Loper, 2001). There was a need in Mount Gambier to assess the potential risk of contaminants from the urban system to adversely impact on groundwater quality and the supply of safe drinking water. A different approach was used in Mount Gambier to model groundwater flows, due to the complex nature of the fractured aquifer. A quantitative risk assessment was undertaken based on a Hazard Analysis and Critical Control Points (HACCP) framework, consistent with the current practice for drinking water management in Australia (NHMRC and NRMMC, 2004) via the following steps: • Assess and quantify potential contaminants. • Document the possible attenuation mechanisms and relevant attenuation coefficients for these contaminants within the Gambier Limestone aquifer and the Blue Lake. • Assess residence time within the aquifer. • Compare the likely concentration after attenuation, in the given residence time, with the appropriate concentration target. An outcome of the HACCP approach is to identify whether water quality is likely to approach guidelines values and hence to determine the costs of interventions to achieve different guidelines. These guideline values can incorporate drinking water (NHMRC and NRMMC, 2004) and aquatic ecosystem targets (SA EPA, 2003). Possible intervention scenarios include control of contaminant sources through planning and governance, repair of leaky sewers, and structural measures such as well head traps to improve the quality of stormwater recharging the aquifer. In the case of public health protection, enhanced treatment of water supplies drawn from the Blue Lake is a further control option if required.
Previous studies have shown that the Blue Lake water is of a good quality, however it is not known whether there are pollutants making their way towards the lake, nor whether the attenuation of such pollutants will be adequate for them to reach the lake in acceptable concentrations. This project will help in quantifying potential risks to Mount Gambier’s water supply and developing strategies to manage these risks.
2.2.4.2 Field studies and Attenuation of Contaminants The experimental program developed for the Mount Gambier case study was developed for several purposes: • To assess residence time in the karst aquifer using tracers (both applied and anthropogenic organic species) from which to base the calculation of saturated zone contaminant attenuation. • To assess site specific stormwater based contaminants for assessment through the HACCP model • To obtain additional water quality data for the suite of parameters common to the AISUWRS program (Cl, Na, K, SO4, B, P, N and organics) in sewage to allow calibration of the UVQ model. • To quantify the potential for B removal through adsorption to carbonate aquifer material (input to SLEAKI and HACCP).
Estimates of aquifer residence time based on aquifer properties are extremely variable due to uncertainties associated with these parameters. Based on an aquifer thickness of 30 m (dolomite unit only) a range in minimum travel time from 1 to 20 years was selected for the risk assessment.
The experimental program examined the feasibility of using anthropogenic species within Blue Lake to verify this residence time estimate. This required the identification of species that could be linked to specific timeframes, or event markers. Thus, we were not necessarily looking to trace specific sources
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 50 to the lake, but instead looking for evidence within the lake of anthropogenic contamination which may be linked to certain intervals. Suitable tracers must be relatively conservative to persist to the Blue Lake and also indicative of a specific interval of time, such as pharmaceuticals. X-ray contrast media have been in use in Australia (including Mount Gambier) since around the 1950’s. Iopromide was detected in all the samples collected from Blue Lake in May 2005, at concentrations of 12 ng/L at the surface, 34 ng/L at 20m, 19 ng/L at 40m and 17 ng/L at 60m and would be indicative sewage migration to the lake within around 50 years. Given that the use of x-ray contrast media in increasing, it would be recommended to include an annual analysis for these types of markers, with sampling recommended when the lake is fully mixed (winter).
Given the extensive dilution within this system, sulphur hexafluoride (SF6) was deemed suitable for estimating minimum residence time with an applied tracer test. SF6, a harmless, non-toxic gas, can be used to ‘tag’ large volumes of water and is detected at extremely low concentrations, which allows groundwater travel times to be determined accurately. Approximately 400 L of water tagged with SF6 was injected into 24 bores in the City of Mount Gambier in August, 2005. Bore selection was based on the bore depth and orientation in relation to Blue Lake. The subsequent SF6 monitoring program within the Blue Lake includes weekly sampling from a pontoon at the pumping station (taken approximately 5 m below the surface) and monthly at four depths (surface, 20 m, 40 m, 60 m) in the centre of the lake. Each sample is collected in triplicate and to date there has not been a positive detection of SF6 in Blue Lake, indicating a minimum travel time greater than four months. Groundwater sampling will be incorporated in the 2006 monitoring plan.
Given that stormwater is reported to constitute up to 35% of the annual recharge to Blue Lake (Blue Lake Management Committee, 2001), the experimental program aimed to explore the temporal and spatial variability of contaminants and to quantify a wider suite of analytes that had previously been considered, in particular organic contaminants.
The field program considered stormwater quality at two locations (SWB141 and SWB125) on two separate occasions using both grab sampling and passive or accumulative sampling techniques. This effectively quantified major ions, nutrients, metals and trace organics within Mount Gambier’s stormwater.
Existing water quality for the Finger Point Waste Water Treatment Plant was supplemented with additional analytes between December 2004 and May 2005 (n=8) to complete the suite of AISUWRS parameters.
Laboratory batch studies indicated no potential for sorption of boron, a nominated sewage tracer, to limestone aquifer material (Vogel, 2005).
The assessment of local data against the concentration target illustrates that total nitrogen inputs in stormwater will not pose a threat to the Blue Lake water quality. While phosphorus inputs in stormwater have the potential to breach the aquatic ecosystem based target value of 0.5 mg/L, there appears to be sufficient attenuation mechanisms in the carbonate aquifer. Phosphorus and nitrogen concentrations within sewage are an order of magnitude higher in the sewage than in stormwater and thus are the species of most concern from the sewage source. Given the dominant influence of stormwater recharge (evident in behaviour of major ions), in conjunction with the efficient removal of P in the unsaturated zone, sewer leaks are not likely to be a large influence on the Blue Lake water quality.
Particulate removal is recommended for the metals and metalloids, and can be achieved by numerous barriers such as increased wellhead treatment facilities. The metals that show incidence of breaching aquatic ecosystem targets are aluminium, chromium, copper and zinc.
Even at the total concentrations quantified in roadside runoff, phenanthrene, fluoranthene and pyrene are a low risk at the source. With adequate particulate removal, input concentrations are likely to be at least two orders of magnitude below the target value. Using the concentrations measured by passive samplers to identify the more mobile PAH fraction, the source concentrations are three orders of magnitude below the aquatic ecosystem target value. Benzene and pentachlorphenol have not been detected locally but are reported as typical stormwater contaminants (Makepeace et al. 1995). However with half-lives of less than 6 months in the aquifer would not be expected to cause a water quality issue. Atrazine and simazine are are predominantly below the analytical detection limit but exhibit peak concentrations above the target value. Again, rapid degradation is expected with half-
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 51 lives less than 6 months.
The current framework for assessing risk to the Blue Lake is structured to deal with uncertainties, or ranges of possible values, with scope for ongoing refinement as knowledge develops. 2.2.4.3 Model Application A range of scenarios were selected and defined for Mount Gambier. These scenarios were developed in consultation with water authorities, local and state government agencies. This enabled the exploration of the likely implications of potential management strategies, such as infrastructure upgrades, on groundwater quality. Also, implications on groundwater of critical future uncertainties, such as climate change or population increase could be explored. The scenarios selected and analysed within the DSS for Mount Gambier were simulated over a thirty year period to allow for the potentially long time between a pollution event and contamination of the groundwater and are described briefly below: • Status quo: Simulates the continuation of current water demand and the climate pattern for Mount Gambier. The climate is based on thirty year climate averages collected from the Mount Gambier weather station. • Climate change: This scenario uses climate inputs based on modelling undertaken by CSIRO Atmospheric Research (Jones, et al., 2001). The climate change scenario for Mount Gambier simulates a decrease in rainfall, and an increase in average temperature and evaporation based on global emission scenarios from the Intergovernmental Panel on Climate Change. • Population increase: This scenario simulates an increase in the Mount Gambier population of 15%, which results in the conversion of 70% of the agricultural land within the defined study area for residential development. Existing vacant land within the city is also developed. • Greywater recycling: In this scenario, 20% of all residential households install a greywater recycling system for garden irrigation and toilet flushing.
The focus of the scenarios is on the quantity of urban water flows rather than quality. There is no difference in the concentration of contaminant sources between scenarios, but there are significant differences in the flow volumes, which then impacts on the total contaminant load being recharged to groundwater.
Analysis of NEIMO shows that leakage of wastewater pipes is on average 3% of the total wastewater volume representing an exfiltration volume of approximately 250 KL/day, which is a small proportion of total groundwater recharge. Therefore, direct recharge of stormwater to drainage wells is likely to be a higher priority management issue. There was no infiltration into wastewater pipes, as they are above the groundwater. Highest leakage volumes from the network were associated with concrete pipes that were laid 40 or more years ago.
The contaminants modelled within the DSS are mostly conservative and therefore there is little or no attenuation of contaminant load through the unsaturated zone. The exception is phosphate where there is significant adsorption in the unsaturated zone under all scenarios. These results are consistent with the lysimeter data obtained from an area close to Mt Gambier where a residence time of a minimum of 100 days is estimated in a soil of pH 8.5 – with no phosphate being detected in the drainage water (Miller et al, 2004).
Worst and best case scenarios were simulated when considering leakage from wastewater pipes. Best case is when exfiltration is occurring at multiple small leaks, while worst case simulates exfiltration from one large defect in the asset. Leaks from sewers typically form a colmation layer that is rich (perhaps 25%) in organic matter. This colmation layer serves to limit the volume of the leaks and also removes a high proportion of the microbes. In smaller leaks the colmation will act to clog and reduce leakage to a steady state quicker than large pipe defect. Results from the DSS showed that concentration of phosphate increased significantly between best and worst case (0 mg/L to ~ 0.85 mg/L), while for the more conservative contaminants there were no significant differences between scenarios.
Nitrogen loads may currently be overestimated, as POSI considers infiltration from below the root zone. The behaviour of species in the root zone, particularly applicable to nitrogen, is a gap in the model chain that is not covered by the DSS.
Under the assumptions of the scenarios modelled in the DSS it is not likely that contaminant concentrations in the groundwater will exceed water quality guidelines. Evaluation of the scenario
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 52 outputs however does indicate the relative risks or impacts of different strategies or potential uncertainties, such as climate change.
Evaluation of the scenarios implemented within the DSS highlights some of the management issues that are faced in ensuring the protection of groundwater quality and the potable water supply for Mount Gambier. The climate change scenario demonstrates a marked reduction in groundwater recharge, which will impact on the Blue Lake water level. The level of the Blue Lake has declined significantly since the early 1900’s, but this fall has accelerated in the last ten years due primarily to lower than average rainfall and a slight increase in extraction (Blue Lake Management Committee, 2001). Analysis of historical data reveals there is a strong correlation between periods of below average rainfall and a decline in lake level. A shift to a drier, hotter climate for Mount Gambier, which is projected under most climate change scenarios, would result in a further decline in the level of the Blue Lake. The population increase scenario shows a significant increase in contaminant loads to groundwater. The conversion of predominately pervious land uses, such as rural, to more intensive urban land use will increase runoff from impervious surfaces and the volume of stormwater being recharged directly to the aquifer via drainage wells. Future urban development within the Blue Lake capture zone will need to consider the likely impact on groundwater quality, and may require alternative stormwater management practices such as incorporation of permeable pavement or roadside swales.
The scenario simulating the implementation of a strategy to increase recycling of household and industrial greywater shows that it would have a significant impact on water demand and also wastewater output. Greywater recycling has the potential to be an important part of a management strategy to reduce the pressure on water levels in the Blue Lake.
The reliance of Mount Gambier on water extracted from the Blue Lake means that identifying and managing potential threats to groundwater quality in the unconfined aquifer is of critical importance. The current water attenuation processes, provided by the saturated zone and in-lake processes such as the annual carbonate precipitation cycle, is adequate for protection against the potential contamination from urban water systems. Furthermore the outcomes from the HACCP model will indicate the relative gain or loss in factors of safety with respect to water quality targets for proposed intervention scenarios. This project will assist Mount Gambier authorities in identifying their preferred management strategy to protect groundwater quality and also develop best practise response to potential scenarios.
2.2.4.4 Socio Economic Aspects and Sustainability Analysis GKW/Futuretec
For Mount Gambier, total annual withdrawal of groundwater via the Blue lake has increased from 4.9 Mm³/y in 1995 to 5.2 Mm³/y in 2005. Lake water level has fallen for 6 m from 1990 to 1997 and reported to have steadily declined since the early 1900’s with an accelerated decline since 1996. The water quality of the lake is in general well within the national guideline values for aesthetics and health and well within the WHO drinking water guidelines. Trends over time however indicate, e.g. for Nitrate, an increase in concentrations during then last decades and attenuation and remediation via the karst structures is very limited. Up to 35% of lake recharge is due to stormwater recharging the Gambier limestone aquifer via drainage boreholes and other structures and poses a hazard to Mount Gambier. With regard to regulations and guidelines, Mount Gambier is quite aware of the problems and risks, however monitoring e.g. of private boreholes is very limited. The utility supplies water almost 100% of the population and the utility’s production could account for > 80% of the total societal demand without losses. The water actually consumed from the public system covers for 50 - 60 % of the societal water demand. All other demand is met via private wells and other private production, which are decentrally distributed and difficult to monitor. Data on water losses indicate a percentage of 24% in 1995 and 28% in 2005 with a trend of increased losses, however on a relative low level. Taking into account the total societal demand for all usage and from all sources, in 1995 an immense rate of 576 l/d would have been demanded per capita for total domestic and non-domestic water use, decreasing to 500 l/cap/d in 2005. App. 80% of the population is connected to the sewer system, sewer exfiltration is not relevant to the city’s decision makers, as the outskirts of Mount Gambier still rely on septic tanks. Wastewater services account for < 40% of the objective of the total societal water demand plus all infiltrating water, assuming that stormwater enters boreholes. BOD loads in the raw wastewater have been slightly increasing, N loads slightly decreased from 1995 to 2005. Primary and secondary treatment is taking
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 53 place in Mount Gambier with a resulting effectiveness of 99% for BOD removal, > 90% for N treatment and 23% (1995) to 43% (2005) for P removal. Effectiveness increased during the last decade. A tertiary treatment step is not in place. Neither energy recovery from biogas nor N and P recycling is currently taking place. Ecosan concepts are so far not under consideration. Stormwater is not collected in the sewer system but infiltrated directly into the aquifer via drainage boreholes and is mainly treated via silt traps. Stormwater management imposes the main future risk mainly due to decentral scattered infiltration into the aquifer that is difficult to monitor.
Thus, the scenario “sewer rehabilitation” did not meet highest relevance for the decision makers, and the rainwater infiltration scenario has not been modelled with the AISUWRS model chain. The greywater loop scenario however indicates that sewer exfiltration could be reduced about app. 1/6 compared to the sewer exfiltration modelled under the present system. Furthermore, the yearly volume of annual treated wastewater decreases and societal drinking water demand would be reduced by app. 0.5 Mm³/y. Furthermore the model results state an improvement of groundwater quality and loads of Boron to soils show a slight reduction under the scenario.
The socio-economic analysis reflects the assessment by the public survey in the city of Mt Gambier.. The following Quality-Importance-Matrix summarizes the assessment of the indicators used:
Importance
t n a t t r t t n o n n a p t a a r t t r im r o t o l o p Improvement is l p n p a a t im t m r im i possible / a o e t y t le p i r t o t u e desirable Quality n li im q v no very good Y little good B N P X I yes improvable M O strongly bad T V U very strongly very bad
Three items are considered as being bad and of importance: Prevention against environmental factors T Pollution of groundwater U Pollution of the Blue Lake V Pollution of soil Thus it can be stated that no actual problems endanger the water sustainability, but there is a lot of sensitivity for future measures to ensure the future course of stable sustainability.
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3 Conclusions including socio-economic relevance, strategic aspects and policy implications
3.1 Scientific conclusions
The AISUWRS project constitutes an important step towards integrated urban water management by offering a chain of interconnected models to link urban water supply, urban drainage and urban groundwater resources in terms of quality and quantity. It incorporates a detailed assessment of the impact of sewer leakage on groundwater which combines the quantification of the source (the leaky sewer network) with the monitoring and modelling of the groundwater as the receiving water body. The investigations were not constrained to popular sum parameters like BOD or COD, but contained a broad suite of highly specific marker substances from pharmaceutics to enteric viruses. The modelling exercises were validated at specific test sites for sewer leakage under operating conditions which were much closer to reality than the laboratory tests documented in contemporary scientific literature. The key outcome of the AISUWRS project is the establishment of a software framework with user interface (AISUWRS DSS) which incorporates all major parts of the urban water and solute balance. Once set up for a case study, it demonstrates the causal directions in urban water management and allows the fast comparison of different scenarios. Within the project, scenarios of climate change, demand change, decentralised rainwater infiltration, greywater reuse and different strategies for sewer rehabilitation were assessed. Apart from the DSS front end, all process models are also available as stand alone versions, along with separate manuals or documentation. Due to the large number of processes considered, the developed model chain requires a large amount of input parameters which constitute an uncertainty factor if not properly known or specified. AISUWRS has aimed to keep the parameters and processes as simple as possible in order to allow the entire water system to be understood and operated by a single user. While the established framework allows qualitative comparisons of the scenarios and indicates probable responses to a specific management option, much effort will also be required in future urban water research to increase the reliability of the quantitative results. The AISUWRS system allows the sensitivity analysis of the individual parameters and can serve as a guideline for future research on the most critical points. The socio-economic analysis in the case study cities sometimes uncovered distinctively different problem perceptions and priorities in the two groups of experts responsible for the water management and the remaining stakeholders. The AISUWRS project has developed tools to foster these urgently required deliberation processes. Methodologies for formal sustainability assessment with a triple bottom line background were also elaborated and tested during the case studies.
3.2 Socio-economic relevance
In order to quantify the impact of urban pollution on groundwater resources the AISUWRS initiative has developed an innovative urban water assessment and management model which is completely in tune with EU policies. Key-indicators for a wide range of contaminants were used as performance indicators in a new, cost-efficient management system which was specially applied for the surveillance of urban areas. Combined with a GIS-supported assessment scheme which was demonstrated within this project, AISUWRS provides innovative urban water management and DSS for both the safeguarding and management of urban groundwater resources to the users (water supply companies and water authorities). Some examples of where AISUWRS research has a direct socio-economic relevance: • Investment costs for the rehabilitation of the public sewer network in Europe are in the range of several hundred billion euros. In Germany alone, the costs have been estimated to be around 45 billion euros. The AISUWRS project answers critical questions with regard to the environmental importance of leaking sewers and offers software tools for the impact assessment. These tools also aid in prioritising necessary rehabilitation measures. • The AISUWRS initiative echoes the public awareness regarding pharmaceuticals and microbiological contamination in drinking water resources. From a neutral standpoint, it has informed a discussion which is often highlighted in the media and sometimes suppressed by
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 55
the public operators. Additional evidence was provided that the major threats to urban water resources are constituted by these trace substances. Consequently, monitoring and sampling strategies need to change from sum parameters to parameters which also incorporate selected marker species. • The easy modelling of urban water management scenarios ensures that a wider range of options can be considered in urban planning. This possibility directly supports innovation, because it permits the assessment of the impacts of changes in policy, engineering practice or externalities. • The assessment of side effects in urban planning using the AISUWRS model chain and the corresponding modification of the implementation plans can prevent environmental and infrastructural damage and thereby save costs. For example, a possible rise in groundwater level causes damage to house foundations and cellars. The repair costs often have to be borne by private owners and are therefore hidden from cost calculations which influence water utility policies. • The software delivered by the AISUWRS project combines widely recognised but essentially qualitative views with quantitative tools. Although still very much at a prototype stage, the achieved advances constitute a solid framework which can be expanded in future through the contribution on particular aspects by smaller research initiatives. • In Europe, there is an increasing introduction of split tariffs for wastewater and stormwater generation. This echoes changing infiltration practices. The AISUWRS approach helps understand the affected processes and consequences. An advantage for European cities is the fact that all of them have water supply and wastewater disposal systems which have evolved over long time periods, in many cases for well over a century. There are very few possibilities for the water infrastructure in such cities to start afresh so that dramatic changes in the water use and disposal practice are highly unlikely. Instead, water management is likely to be gradually improved, whereby some policies or incentive/disincentive measures might be attractive in one particular situation but not in another. Similarly, some water utilities will be better placed or more inclined to incorporate particular technological or methodological changes than others. Nevertheless, despite old traditions and sometimes an even older infrastructure, European water utilities have frequently been at the forefront of technical and managerial innovation. One example would be the wastewater treatment methods which are often open to change once the benefits of a change have been demonstrated. For the demonstration, the co-operation with researchers in newer Australian cities, where ongoing urbanisation is new, experimental systems are easier to test and where there is a societal openness to innovation, is a great advantage. As there is a large number of possible urban water and groundwater contaminants, it is sensible and pragmatic to develop an urban water and contaminant balance model and management system which works with a limited number of significant components, which serve as pollution indicator for the urban area as a whole. In order to protect the high quality of the water resources, it is important to identify contamination early when the levels are still relatively low. This also helps identify and characterise the sources of contamination and observe long-term trends. As a multidisciplinary research effort is required to develop such a method, the AISUWRS project has initiated a very productive co-operation between European specialists in urban water and groundwater systems and world leading experts for the modelling and assessment of urban systems in Australia.
3.3 Strategic aspects & policy implications
The AISUWRS project’s results directly link to the research agenda, vision documents and action plans which are currently discussed at a European level within the Water Supply and Sanitation Technology Platform. The Water Supply and Sanitation Technology Platform (WSSTP) is one of the technology platforms that are set up within the European Environmental Technology Action Plan (ETAP) which was adopted by the European Commission in 2004. It is a European initiative, open to all stakeholders involved in European water supply and sanitation and major end-user groups. The participants in the platform are working on a common vision document for the whole European water industry as well as a strategic research agenda and a short (2010), medium (2020) and long term (2030) implementation plan. The key vision statement of thematic working group 2 (TWG 2), Sector Water for People, with the focus on water supply and sanitation in urban, periurban and rural areas is cited as follows:
Assessing and Improving the Sustainability of Urban Water Resources and Systems – Final Project Report 56
By 2030 the European water sector, by developing its ability to apply a variety of integrated approaches and technologies to successfully solve a diverse range of problems, will be regarded as the leading centre of expertise for providing safe, clean, affordable water and sanitation, using efficient and sustainable technologies which will enhance the social, economic and environmental well being of the community and the health and well-being of the planet and its peoples (http://www.wsstp.org).
By integrating the knowledge of leading Australian experts and shifting from basic research towards stakeholder oriented software tools and research products, AISUWRS has actively worked towards this vision.
On reviewing the current iterations of the WSSTP’s documents, it becomes apparent that groundwater is not sufficiently considered in the urban water and resource planning. This partly originates in a traditional separation of hydrogeological research and common engineering practices. AISUWRS enclosed experiences from both sectors and demonstrated the benefit of this interdisciplinary co- operation. From the viewpoint of the project members, continuing with this approach in future research and applications is necessary to achieve the idea of “Integrated Urban Water Management”. AISUWRS has demonstrated that a sustainable use of urban groundwater is possible if properly managed and therefore propels the idea of “closed loops” in urban water systems. This can substantially reduce the pressures from the fast growth of metropolitan areas.
AISUWRS also addresses the Water Framework Directive (WFD), which came into force in 2000, and in this respect provides a clear sustainability message. As part of a comprehensive strategy for managing the water environment, member states have environmental objectives for groundwater (Article 4.1[b] of the WFD) which require them to: • Prevent or limit the input of pollutants into groundwater and prevent deterioration in status • Protect, enhance and restore all groundwater bodies, with the aim of achieving good status • Reverse upward trends in the concentration of any pollutant.
AISUWRS was designed to meet the demands of European policies, as stated in the following reports:
• The document “The research programmes of the European Union 1998-2002” (EUR 18764) states that “the pipes, long considered indestructible, are in fact leaking at an alarming rate. No European standard exists to access the operation of such systems, and expertise is often confined to a national or regional level”. The consortium of the AISUWRS project comprises all the major research environments that were necessary to contribute to solving this problem. • In 1997, the European Commission released the document “Research Industry. Task Forces”, in which it is stated that “Water has become a coveted economic good, whose management will be one of the major problems of the 21st century”. It is further stated that between 15 % and 30 % of the produced water is lost in distribution and that “there are big gaps between operators and regions in terms of technological performance and management capabilities”. • The need of an improved common framework for the protection of inland surface water and ground water is handled in a comprehensive work released on 30 November 1999, with an invitation to the European Parliament to adopt it as an EU directive. Some of the major objectives of this directive is to “promote sustainable water use based on a long-tem protection of available water resources and to mitigate the effects of drought”.
AISUWRS has contributed to the mitigation of these problems by the research on cost-effective monitoring strategies, by defining the true dimension of the sewer leakage problem and by the development of a well documented software framework which can be used by all concerned parties.
The AISUWRS project may be used for further European standardisations or recommendations: • in the field of databases for water services and resources management, • in the field of rehabilitation techniques, • in the field of methods to assess the state of urban water resources • in the field of methods to assess the condition of sewer pipes. • In the field of assessing likely long-term trends in urban aquifer water levels and their possible impact on a city’s engineered infrastructure
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During the AISUWRS initiative, tools for a future application with regard to the assessment of urban water systems were developed and guidelines for the use of these instruments were elaborated. These tools can help urban decision makers primarily in the analysis of the current situation of the urban water system but also in the analysis of the environmental or socio-economic impact of alternative measures or different scenarios. The AISUWRS initiative thus aims to guide the executive parties on the way to making their decision on a sustainable urban water system. The impact of water pollution is a substantial European and global problem that is observed even in the most remote areas of our planet. In spite of international conventions on water pollution (UN, EU, ECE), groundwater resources are still affected and endangered by anthropogenic impacts and through many urban contaminant sources.
4 Dissemination and exploitation of the results
4.1 Dissemination pathways (AGK/BGS)
The AISUWRS project has been actively pursuing the dissemination of the project concept and results since its very start. The scientific community has been a major target of the dissemination activities as the project introduces a new thinking in urban water systems and relies on the intense discussion with other innovative research workers. At least 50 oral presentations were given at international conferences and workshops. Every conference included the publication of abstracts and long papers were written in more than 36 cases. Six papers have already been published in international journals, six papers have passed the review process and await publication and 4 additional papers have been submitted. Several additional paper productions are envisaged in 2006. Two diploma theses were completed. A significant part of the research work will be published in the course of two PhD-theses, due to finish in 2006. An important final dissemination product which is underway at the time of the writing of this summary is the production of a book, sponsored by the IWA that will describe the AISUWRS process in detail, illustrate its application in the case-study cities, demonstrate the socio-economic aspects of the water management process and provide guidelines for those wishing to develop these prototype tools for operational use. The book is to be A4 format, colour, about 350 pages in length and currently scheduled to be completed and published in the spring of 2006. In Australia, the high public awareness to water related problems lead to a significant media interest in the project. As a result, an Australian press release on the AISUWRS project with Mt Gambier as the case study site for Australia was published on 2 March 2004. The release was also published in CSIRO’s Innovation magazine http://www.cmit.csiro.au/innovation/2004-02/aisuwrs.cfm. A TV- documentary on the AISUWRS project was filmed during the MtGambier meeting and broadcasted on the “Win News” TV station on 4 March 2004. Several additional newspaper articles followed in 2005. Additional dissemination of project results to the local stakeholders was undertaken in the course of the socio-economic surveys and stakeholder interviews. Besides the public utilities and regulatory agencies (in all case studies), representatives of political parties were also informed about the scope of the project and subsequently interviewed (e.g. in Rastatt). In Mount Gambier, a computer-based information system was installed at the frequently visited public library. Given the possibility for direct interaction people were more likely to submit information. A similar phenomenon was observed during the direct household surveys in Rastatt. Dissemination to stakeholders was undertaken throughout the project for the Doncaster case-study. This was formally done by the production and circulation of two newsletters during years 1 and 2 of the project, and by the participation of all key stakeholders in the regular 6-monthly project coordination meeting hosted in Doncaster in October 2004. Additionally, informal links were maintained through discussion with contact staff members throughout the project, especially at Yorkshire Water and Doncaster Council. A brief AISUWRS newsletter in German was also distributed to key stakeholders in Rastatt. In December 2005, a final overview of project results was presented and discussed with the local agencies and city departments. From the start, the AISUWRS project has maintained a website (http://www.urbanwater.de/) with both a public access and limited access section (the latter serving as a project office). This site has played an important internal dissemination role in a project where experts from quite a number of different fields have to closely work together to achieve the tasks detailed in the work packages.
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The dissemination of project results is currently also ongoing through activities inside the CityNet project which has been extended through December 2006. AISUWRS will contribute a study module related to urban groundwater. The study module is intended to form part of a summer school on integrated urban water management. Furthermore, AISUWRS will use the established network of end-user contacts from the CityNet cluster for further dissemination.
4.2 Future availability and applications of the AISUWRS approach
The future availability of the AISUWRS concept is secured by the publication of the central guideline document as a high quality book produced in co-operation with the International Water Association (IWA). The IWA is the largest international organisation in this field and maintains a sophisticated distribution system with online availability.
Furthermore, the entire project documentation, including all public deliverables, will be available at the project homepage (www.urbanwater.de) after the project is finished.
It has been decided among the project partners that the developed software products will be made available as shareware. While some contractual details remain to be clarified, there is a consensus that the project homepage will either contain direct download possibilities or indicate how to obtain the software. While extensive documentation exists, experiences gathered during the project show the complexity of the addressed issues. For large scale applications, it is recommended that new users contact the developers and project members for consultation.
5 Literature produced within the AISUWRS project
The public project deliverables are listed in the results section of the AISUWRS homepage and can be directly accessed. These include:
- Case study city reports (background, interim & final reports)
- Model descriptions and manuals
- Application reports
In addition to these open-file reports and as a result of the highly innovative and technically- challenging complexity of the topic area, the project as a whole has been particularly prolific in the production of papers for conferences and peer-reviewed journals:
Peer Reviewed Articles:
Authors Date Title Journal Reference Burn, S., Eiswirth In print Aging Matthias Eiswirth Memorial In print M., DeSilva D, infrastructure Volume, IAH special book Mitchell G,. Correll and its impact on series R., Dillon P., Wolf Urban L., Mohrlok U., Groundwater Morris B., and Vizinitin G.
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DeSilva,D., Burn, 2005 Sustainable Water Science and Vol 52, Issue S., Management of Technology 12, 189-198 Tjandraatmadja, Leakage from G., . Moglia, M., Wastewater Davis, P., Wolf,, Pipelines L.,Held, I., Vollertsen, J., Williams, W. and Hafskjold, L.
Eiswirth, M., Wolf, 2004 Balancing the Environmental Geology, Volume 46, L. Hötzl, H. contaminant Springer Verlag, Heidelberg. Number 2. pp input into urban 246 - 256. water resources, Environmental Geology Held, I., Klinger, In print Direct Matthias Eiswirth Memorial In print J., Wolf, L., Hötzl, measurements Volume,IAH special book H. of exfiltration in a series sewer test site under operating conditions Juren, A., Pregl, 2003 Project of an RMZ mater. Geoenviron, 50(1): 153-156 M., Veselič M. urban lysimeter at the Union Brewery, Ljubljana, Slovenia Mitchell V.G., 2005 Simulating the Environmental Modelling and In print Diaper C. Urban Water and Software. contaminant cycle Mohrlok, U., 2004 Assessment of Acta hydrochimica et Vol. 32, No. 4- Bücker-Gittel, M., Wastewater hydrobiologica. 5. pp. 328-335. Cata, C., Jirka, Impact on G.H. Groundwater by Hydraulic Soil Investigations Mohrlok, U., Cata, In print Impact on urban Matthias Eiswirth Memorial In print C., Bücker-Gittel, groundwater by Volume, IAH special book M. wastewater series infiltration into soils Morris BL, Darling (In Assessing the Hydrogeology Journal Accepted Oct WG, Cronin AA, press impact of 2005; ex[ected Rueedi J, 2006), modern recharge online Whitehead EJ, on a sandstone publication Gooddy DC aquifer beneath early 2006 a suburb of Doncaster UK. Rueedi, J, Cronin 2004 Effect of different Water Science and Vol 52, Issue 9, A, Moon, B, Wolf, water supply Technology pp.115-123. L, Hoetzl, H strategies on water and contaminant fluxes in Doncaster, United Kingdom.
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Wolf, L, Hötzl, H. In print Upscaling of Matthias Eiswirth Memorial In print laboratory results Volume, IAH special book on sewer series leakage and the associated uncertainty Wolf, L. Eiswirth, In print Assessing Environmental Geology, In print M. Hötzl, H. sewer- Springer Verlag, Heidelberg. groundwater interaction at the city scale based on individual sewer defects and marker species distributions Wolf, L., Held, I., 2004 Impact of leaky Acta hydrochimica et Vol. 32, No. 4- Eiswirth, M., and sewers on hydrobiologica. 5. pp. 361-373. Hötzl, H. groundwater quality
Non refereed literature:
Authors / Editors Date Title Event Reference Type Bücker-Gittel, M., 2003 Modelling In: K. Kovar, Z. IAHS publication Oral Mohrlok, U., Jirka, unsaturated Hrkal (eds.), no. 277, presentati G.H. water transport Calibration and Wallingford, UK, on and using a random reliability in 17-21 Proceedin walk approach groundwater gs modelling – a few steps closer to reality
Burn, S., De Silva 2003 Aging AWA Victorian AWA publication Oral D., infrastructure Regional presentati Tjandraatmadja, and its impact on Branch on and G. Urban Conference, Proceedin Groundwater Water – gs Victoria’s Future, 16-18 October 2003 Burn, S., DeSilva, 2005 A Decision 10th Proceedings on Oral D., Ambrose, M., Support System International CD Rom presentati Meddings, S., for Urban Conference on on and Diaper, C., Correll Groundwater Urban Proceedin , R., Miller, R., and Resource Drainage. gs Wolf, L. Sustainability Copenhagen, Denmark, August 2005 Burn, S., DeSilva, 2003 The role of Pipes Wagga on CD-ROM Oral D., Urban Wagga, 20-23 presentati Tjandraatmadja, Infrastructure on October, on and G., Dillon, P., groundwater Wagga Wagga, Proceedin Diaper, C., Correll, contamination – Australia gs R., Eiswirth, M. the EU AISUWRS project Cata, C., Mohrlok, 2004 Modelling waste FH-DGG Schriftenreihe Poster U. water transport Conference, der Deutschen and and 19.-23. May Geologischen proceedin transformation in 2004, Gesellschaft gs
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unsaturated Darmstadt, (32), p. 136 media Cata, C., Mohrlok, 2004 Wastewater XXXIII on CD-ROM Poster U. transport and Congress IAH and transformation in & 7th Congress proceedin unsaturated ALHSUD, gs zone Zacatecas, Mexico Cata, C., Mohrlok, 2005 A random-walk Conference Pre-Published Oral U. approach for ModelCARE Proceedings, pp. presentati simulating 2005, The 522-527 on and wastewater Hague, The Proceedin transport and Netherlands gs transformation in the unsaturated zone Čenčur Curk, B. & 2005 Ugotavljanje 17. Abstract Volume, Oral Pregl, M. poteka vodne posvetovanje pp. 20-21 presentati fronte v slovenskih on and nezasičeni coni geologov (17th Proceedin prodnatega Meeting of gs vodonosnika s Slovenian pomočjo meritev Geologists), fizikalnih 8.4.2005, parametrov v Ljubljana, lizimetru Union Slovenia Čenčur Curk, B., 2005 Establishing an Lysimetres in Abstract Volume, Poster Pregl, M. & Moon, urban lysimeter the Network of pp. 149-150 and B. at the Union Dynamics of Proceedin Brewery, Ecosystems, 5- gs Ljubljana, 6.4. 2005, Slovenia Raumberg- Gumpenstein (Austria) Cronin, A.A. 2005 The effects of IAH Oral Rueedi, J., Taylor, sewer leakage Groundwater Presentati R.G. on urban Seminar in on groundwater Tullamore, systems Ireland, April 2005 Cronin, A.A., 2005 The usefulness 10th Proceedings on Oral Rueedi, J, Morris, of microbial and International CD Rom presentati B.L. chemical Conference on on and indicators to Urban Proceedin detect sewer Drainage. gs leakage impacts Copenhagen, on urban Denmark, groundwater August 2005 quality Cronin, A.A., 2004 Monitoring, NATO Proceedings to Oral Rueedi, J., Joyce, understanding, conference on be published in presentati E., Pedley, S. and managing urban water. book format. on and the extent of Baku, Proceedin microbiological Azerbeijan. gs pollution in urban groundwater systems in developed and developing country cities Cunningham J., 2004 Geographic 2nd CIWEM Technical Conferen
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Morris B., Rueedi Information National session 4; Water ce paper J. System Analysis Conference, Resources & in pipe Wakefield UK, Water Quality infrastructure 5-8 September modelling: 2004 making the most of available data Cunningham J., 2005 Urban CIWEM West Session 2: Conferen Morris B., Rueedi groundwater Midlands collection ce paper J. management Annual systems Conference, 14 April 2005 DeSilva, D., Burn, 2003 Development of Pipes Wagga on CD-ROM Oral S., Davis, P., and a Decision Wagga, 20-23 presentati Moglia, M. Support System October, on and for Sewer Wagga Wagga, Proceedin Rehabilitation Australia gs DeSilva, D., Burn, 2004 Sustainable IWA world on CD-ROM Oral S., Management of Water presentati Tjandraatmadja, Leakage from Congress, on and G., Moglia,M., Wastewater Sept. 2004, Proceedin Davis, P., Wolf, L., Pipelines Marrakech gs Held, I., Vollertsen, J., Williams, W., Hafskjold, L. Eiswirth, M., Hötzl, 2003 Assessing and IAH conference RMZ mater. Oral H., Cronin, A., Improving in Bled, Geoenviron, pp. presentati Morris, B., Sustainability of Slovenia 117-120 on and Veselič, M. Bufler, Urban Water Proceedin R. Burn, S. & Resources and gs Dillon. P. Systems Eiswirth, M., 2004 Urban 14th Stockholm Abstract Volume, Oral Mohrlok, U., groundwater Water pp. 329-330. presentati Hoetzl, H., Wolf, assessment and Symposium, on and L., Burn, S., management 16-20 August proceedin Dillon, P., Morris, tool based on 2004 gs B., Cronin, A., urban water Veselic, M., Voett, balance U. modelling including leaking sewers. Eiswirth, M., Wolf, 2002 Balancing the IAH conference on CD-ROM Oral L. & Hötzl, H. contaminant Mar del Plata, presentati input into urban Argentina on and water resources Proceedin gs Eiswirth, M., Wolf, 2003 Assessing the Workshop Mitteilung Institut Oral L. & Hötzl, H. sustainability of “Diffuse input of Grundwasserwirt presentati urban water chemicals into schaft TU on and resources soil and Dresden, Bd. 3, Proceedin groundwater”, pp. 205-215 gs 26-28 Feb 2003 Held, I. Eiswirth, 2004 Impacts of sewer NATO Proceedings to Oral M., Wolf, L., Hötzl, leakage on conference on be published in presentati H. 2004 urban urban water. book format. on and groundwater – Baku, Proceedin review of results Azerbeijan. gs from a case study in Germany.
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Held, I., Eiswirth, 2004 Hydrochemische FH-DGG Schriftenreihe Poster M, Wolf, L., Hötzl, Veränderungen Conference, der Deutschen and H. im näheren 19.-23. May Geologischen proceedin Umfeld von 2004, Gesellschaft gs Kanalleckagen Darmstadt, (32), p.145 Held, I., Eiswirth, 2004 Hydrochemical 32.IGC Proceedings on Oral M., Wolf. & Hötzl, variations in the Conference, CD Rom presentati H. close Florence 20- on and environment of 28.August Proceedin leaky sewers 2004. gs Held, I., Eiswirth, 2004 Leaky sewers as XXXIII IAH & 7º Proceedings on Oral M., Wolf. & Hötzl, a source for ALHSUD CD Rom presentati H.. groundwater Congress on and recharge and October 11th - Proceedin quality changes 15th 2004 gs Zacatecas, Mexico. Joyce, E., Cronin, 2004 Microbial Groundwater Oral A.A., Rueedi, J., contamination of Quality 2004, presentati Pedley, S., Hart, urban water – Waterloo, on and A.J., Humble, P.J. quantifying the Canada. Proceedin problem and gs understanding the processes Klinger, J, Wolf, L. 2004 Using the UVQ 19th EJSW www.urbanwater Oral Model for the Workshop on .de presentati sustainability Process Data www.unife- on and assessment of and Integrated citynet.it proceedin the urban water Urban Water gs system Modelling Klinger, J., Wolf, 2005 Leaky sewers – 4th World Wide Proceedings and Oral L., Hötzl, H. Measurements Workshop for online availability presentati under operating Young at on and conditions Environmental http://www.enpc.f proceedin Scientists r/cereve/www- gs (WWW-YES), yes/WWW-YES- Urban waters: 2005-First- resource or risk Circular.html. Klinger, J., Wolf, 2005 New modeling EWRA2005- Proceedings Oral L., Hötzl, H. tools for sewer Sharing a presentati leakage common vision on and assessment and for our water proceedin the validation at resources, 6th gs a real world test International site. Conference, 7- 10. Sept. 2005, Menton, France Klinger, J., Wolf, 2005 Application of AVR05 - Proceedings Oral L., Hötzl, H. computer tools to Aquifer presentati assess the Vulnerability on and impact risk of and Risk, 21-23 proceedin groundwater due Sept. 2005 - gs to urbanization Reggia di Colorno (PR), Italy Mitchell, V.G., 2003 UVQ: Modelling 28th Hydrology Vol 3, pp 131- Oral Diaper, C, Gray, the Movement of and Water 138 presentati S.R. and Rahilly, Water and Resources on and M Contaminants Symposium, Proceedin through the Total Institution of gs Urban Water Engineers
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Cycle Australia, 10 – 14 November, Wollongong, NSW Mohrlok, U. 2004 Regionalisierung FH-DGG Schriftenreihe Oral von Conference, der Deutschen presentati Punktinfiltratione 19.-23. May Geologischen on and n aus 2004, Gesellschaft proceedin Leitungsleckage Darmstadt, (32), p.26 gs n in den urbanen Untergrund zur Ermittlung der Grundwasserneu bildung. Mohrlok, U., Cata 2005 Risk assessment 2nd European Proceedings, Poster C., Bücker-Gittel, of sewer leaks Conference on Book of presentati M. for soils and Natural Abstracts, p. 93. on and groundwater by Attenuation, proceedin means of Soil and gs numerical flow Groundwater and transport Risk studies Management, 18.-20. May 2005, Franfurt Mohrlok, U., Wolf, 2005 Estimation of 10th Proceedings on Poster L., Klinger, J. urban International CD Rom presentati groundwater Conference on on and recharge from Urban proceedin different sources Drainage, 21- gs by quantifying 26 August soil seepage 2005, processes Copenhagen, Denmark Morris, B.L., 2005 Groundwater 10th Proceedings on Oral Neumann, I., surcharging of International CD Rom presentati Cunningham, J., sewers: example Conference on on and Hargreaves, R., from Doncaster, Urban Proceedin Rueedi, J. Cronin, England of a Drainage. gs A.A. technique for Copenhagen, identifying its Denmark, extent August 2005 Rosemann, S. 2004 The protective Master Thesis Departme function of the nt of unsaturated Applied zone and the Geology, monitoring of University stormwater of quality of Mount Karlsruhe Gambier, South Australia. Rueedi, J, Cronin 2004 Effect of different IWA 4th World on CD-ROM Oral A, Moon, B, Wolf, water supply Water presentati L, Hoetzl, H strategies on Congress, on and water and Sept. 2004, proceedin contaminant Marrakech gs fluxes in Morocco, Doncaster, United Kingdom. Rueedi, J. 2005 Integrated Urban Oral Oral Water Presentation at presentati
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Management: EAWAG on and Results from the Seminar, Abstract AISUWRS case Duebendorf, study Doncaster Switzerland Rueedi, J., Cronin, 2005 Daily patterns of 10th Proceedings on Oral A.A. micro-organisms International CD Rom presentati in the foul sewer Conference on on and system of Don- Urban Proceedin caster, UK Drainage. gs Copenhagen, Denmark, August 2005 S. Burn, R. Correll, 2004 Aging IWA world on CD-ROM Poster A. Cronin, D. Infrastructure Water DeSilva, P. Dillon, and Its Impact on Congress, M. Eiswirth, G. Urban Sept. 2004, Mitchell, U. Groundwater. Marrakech Mohrlok, B. Morris, J. Rueedi, L. Wolf, G. Vizintin and U. Vött. Souvent, P., 2005 Ocena Strokovno Proceedings, Oral Vižintin, G. & ogroženosti posvetovanje pp. 31-45 presentati Čenčur Curk, B. podzemne vode “Kakovost pitne on and v urbanem okolju vode 2005”, 16- proceedin 18 November, gs Ljubljana, Slovenia Souvent, P., 2005 Vpliv kanalizacije 17. Abstract Volume, Poster Vižintin, G. & na kvaliteto posvetovanje pp. 115-116 and Moon, B. vodonosnika slovenskih Proceedin Ljubljanskega geologov (17th gs polja Meeting of Slovenian Geologists), 8.4.2005, Ljubljana, Slovenia Trček, B. & Juren, 2004 Flow and solute 32.IGC Proceedings on Oral A. transport Conference, CD Rom presentati monitorring at an Florence 20- on and urban lysimeter 28.August Proceedin of Union 2004. gs brewery, Ljubljana, Slovenia Trček, B. & Juren, 2005 Hydrogeochemic 10th Proceedings on Oral A. al investigations International CD Rom presentati in an urban area Conference on on and of Union Urban Proceedin Brewery, Drainage. gs Ljubljana, Copenhagen, Slovenia Denmark, August 2005 Trček, B. & Juren, 2005 Hydro- Lysimetres in Abstract Volume, Oral A. geochemical the Network of pp. 149-115 presentati investigations at Dynamics of on and an urban Ecosystems, 5- Proceedin lysimeter of 6.4. 2005, gs Union brewery, Raumberg- Ljubljana, Gumpenstein
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Slovenia (Austria)
Vanderzalm, J. L., 2004 Impact of International Oral Schiller, T., Dillon, stormwater Conference on presentati P. J. and Burn, S. recharge on Blue Water Sensitive on and Lake, Mount Urban Design Proceedin Gambier’s (WSUD2004): gs drinking water Cities as supply Catchments, Adelaide 21-25 November 2004. Wolf, L, Eiswirth, 2004 Modellrechnunge FH-DGG Schriftenreihe Oral M, Held, I., n zur Conference, der Deutschen presentati Klinger, J., Hötzl, Grundwasserbee 19.-23. May Geologischen on and H. influssung durch 2004, Gesellschaft proceedin Kanalleckagen Darmstadt, (32), p.27 gs im Nah- und Germany. Fernfeld. Wolf, L, Hötzl, H. 2004 Berücksichtigung 6.Fachtagung Proceedings Oral undichter Grafikgestützte presentati Kanalisationssys Grundwasserm on and teme in odellierung, 14- paper in numerischen 15.6.2004, Köln proceedin Grundwassermo gs dellen Wolf, L. 2004 Integrating leaky 19 EJSW www.urbanwater Oral sewers into Workshop on .de presentati numerical Process Data www.unife- on and groundwater and Integrated citynet.it proceedin models Urban Water gs Modelling Wolf, L., Eiswirth, 2003 Assessing IAH conference RMZ mater. Oral M. & Hötzl. H. sewer- in Bled, Geoenviron, presentati groundwater Slovenia pp.423-426 on and interaction at the Proceedin city scale based gs on individual sewer defects Wolf, L., Eiswirth, 2004 Linking urban 32.IGC Proceedings on Oral M., Klinger, J. & water Conference, CD Rom presentati Hötzl, H. infrastructure Florence 20- on and with numerical 28.August Proceedin groundwater 2004. gs models Wolf, L., Held, I., 2005 Integrating 10th Proceedings on Oral Klinger, J., Hoetzl, Groundwater into International CD Rom presentati H Urban Water Conference on on and Management – Urban Proceedin The AISUWRS Drainage. gs project. Copenhagen, Denmark, August 2005
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Wolf, L., Hötzl, H. 2004 Developing DFG Workshop Proceedings Poster modelling tools on Integrated and for management Water proceedin of urban Research and gs groundwater Water resources Management, 28-29.6.2004, Kassel (Germany). Wolf, L., Klinger, 2005 Connecting ConSoil 2005, Proceedings on Oral J., Hötzl, H., urban surface Bordeaux, CD-Rom, presentati Schrage, C., Burn, water systems France. Abstract in on and S., DeSilva, Dh., and groundwater booklet proceedin Correll, R., – Application of a gs Rueedi, J., Cronin, new model chain A.A., Morris, B., to four case Vizintin, G., Voett, study cities U., Hoering, K., Mohrlok, U.
Wunderlich, K. 2005 GIS gestützte Diploma Thesis Universitä Modellierung der t Rostock, hydrologischen Institut für Prozesse im Umweltin urbanen Raum genieurw am Beispiel der esen Städte Nantes (Frankreich) und Rastatt (Deutschland)
Major submitted papers: Rueedi, J., Cronin, A.A., Morris, B.L. (submitted). Estimating sewer leakage using hydrochemistry sampling of multilevel piezometers, submitted 2005 to Water Research. Rueedi, J., Cronin, A.A., Taylor, R.G. and Morris, B.L. (submitted). Tracing sources of carbon in urban 13 groundwater using δ CTDIC ratios. Submitted to Chemical Geology.
6 Additional References
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