Urban Water Management: Science Technology and Service Delivery

Frequently reported degradation of urban waters indicates that discharges of urban stormwater may cause a variety of impacts in receiving waters [1]. Such impacts can be characterised with respect to their nature, time scales, spatial scales, and the types of receiving waters. The nature of the impact is usually classified as physical, chemical, microbiological or combined. Examples of physical impacts include increased flows (and reduced recharge of groundwater aquifers), erosion and sediment transport/deposition, temperature rise, and densimetric stratification. Chemical impacts contribute to changes in water quality through dissolved oxygen depletion, nutrient enrichment and eutrophication, and toxicity (both acute and chronic). Microbiological impacts may affect both recreational waters and shellfish harvesting areas. Finally, it should be recognised that these types of impacts usually occur in various combinations, which may be referred to as combined impacts and further described by ecological impacts and impairments of beneficial water uses.

Water Management has become a very important has become a complex integrated management task. With EU Framework Directive it will be compulsory to make water management plans for river basins including the affected estuaries. Municipal waste water management as part of urban water management has to be integrated into these plans. It is therefore necessary to discuss the waste water treatment policy in regard to the influence on the receiving water quality. With decreasing dilution of the treatment plant effluent by the receiving water the influence of the treated waste water on pollution concentration will increase, while the pollution load is not affected by dilution. As the receiving waters of most of the Central and Eastern European countries have international river basins discharging to land locked seas with sensitive estuaries minimum treatment efficiency requirements should take this into consideration. The decisions have to be based on political, ecological and economical considerations. The Austrian experience can be used to demonstrate the consequences of 4 decades of consequent water protection policy and to illustrate the adaptation to EU directives, especially to the Urban Waste Water Directive 271/91.

The objective of this paper for the ARW workshop is to express our view on the use of modelling tools, and mainly Decision Support Systems (DSS) in Water and Environment for identifying the best strategy for future investment. We will focus on Structural funds of EU as the target goal and not on ISPA funding, which is going on in several CEE countries. The Structural Funds will be very important for future navigation and good preparation of engineers in the Central and Eastern Europe.

Czech Republic has a total area of 78,866 km2 and lies between two neighbouring mountain ranges (Czech highlands and Carpathians). The hilly terrain is distinguished by significant differences in elevation (1602 metres above sea level for the mountain Sne•ka and 115 m above sea level for the valley of the River Elbe). Most of the territory has a altitude above sea level 200–600 m. The annual average precipitation is 668 mm, with the driest area in North-West Bohemia (450 mm) and the greatest average rainfall on the ridges of Jizerské Mountains (1700 mm). Water resources in the Czech Republic are replenished almost exclusively by precipitation. Their volume represents in a long-term average 16,7 billion m3/year, with a minimum of 9 billion m3/year and the maximum of 19 billion m3/year. The Czech Republic is the country with moderate and unevenly distributed water resources. Approximately 30–50 % of water resources can be considered usable. The territory of the Czech Republic is an important European watershed with the upper reaches of basins of large European rivers such as Elbe, Odra and Danube. The total length of watercourses in the Czech Republic exceeds 76,000 km. In terms of water management, the long-term trend of reducing released pollutants is having positive impact on the watercourses, with respect to the basic parameters of conventional pollution of surface waters. Despite the implementation of many measures for controlling sources of pollution and the achievement of a significant improvement in the elimination of heavy metals and organic substances in water, not all problems associated with quality of surface water have yet been resolved.

Groundwater constitutes an important component of the hydrologic cycle. It links earth surface and surface receiving water. With increased anthropological load, sometimes above permissible levels, groundwater quality often deteriorates. In the last few decades public, scientific and management attention has been focused on groundwater and soil contamination by hazardous industrial waste, oil spills, sites of radioactive waste repositories, military ammunition, domestic waste and other sources

Water is of vital importance both for human life and for the life of cities. Factually all cities of the world are built in a close proximity to rivers, seas and water bodies.

Since the political changes in 1989, greater attention has been paid to the environmental policy of the Czech Republic. The top priority of the Czech foreign policy is to join the European Union. A lot of steps within a pre-accession process have to be done. Firstly, a legislation process of harmonization must be accelerated in order to include EU standards. Secondly, the government must provide the state administration with finances. Thirdly, it is important to establish control procedures and penalties in case of law violations. In order to achieve the above-mentioned requirements for water management, huge investment to the infrastructure and water sector itself will be needed. Political goals of the Czech Republic and new sources for investment, e.g. ISPA funds, influence also positively the water sector in Prague.

Protections from floods and flood mitigation always have been of great concern to human civilisations and nowadays it represents an important part of the hydraulic engineering. Urban flooding in particular is still one of the most dangerous natural events affecting the human life and living conditions of millions of people all over the world.

During the last decade a growing interest could be noticed in problems related to model based decision support in general (Scholten & Udink ten Cate, 1996) and also specifically in water management. These problems are manifold and include, but are not restricted to technical problems associated with modelling and simulation software, data handling, measuring errors and other uncertainty in system observations, selection of an appropriate model, lack of data, error propagation in coupled models, the increased technological power to calibrate complex models, soft, procedural items associated with stakeholder participation, and translating model results to the level of understanding of managers and decision makers.

Urban runoff quantity and quality is a major problem for the sustainable development of our cities. Up to the 1960s, little attention was given to the pollution caused by storm sewer flows. Since that time, many important programs have been set up in order to understand the nature of runoff pollution. In the United States, the most comprehensive study was the Nationwide Urban Runoff Program (NURP) conducted by EPA between 1978 and 1983. Moreover runoff pollution data were collected under the monitoring program called the National Pollutant Discharge Elimination System (NPDES) which was established to regulate storm water point source discharges by permit requirements. Extensive investigations were also conducted in France since 1970 and the data collected on the quality of wet weather flows have been gathered and analysed in the QASTOR database. In Italy, since the 1980’s about ten experimental urban catchments have been instrumented for runoff quantity monitoring studies (Pagliara, 2000), and later the investigation has been extended also to water quality data. The University of Pisa has instrumented two stormwater basins: “Fiumetto”, for which three years of water quantity data are available and “Picchianti” with quantity and quality measurements. In the national context, the experimental catchment of Picchianti is one of the very few cases of an urban site drained by a separate storm sewer network in operation.

Bruce [1] described the concept of the National Flood Damage Reduction Program. A national program to reduce flood damages was announced by the federal Minister of the Environment in April, 1975. Considerations that went into the program and its evolution are presented. Past governmental contributions to flood relief and flood control structures have not curbed floodplain investment processes nor the concomitant increase in damage potential. The new program is intended to coordinate federal and provincial strategies by clearly defining flood-risk areas, by discouraging continuing investment in those areas, and by following up with appropriate measures to limit damage to existing development. General agreements are being negotiated with most provinces which will confirm the underlying principles and facilitate flood-risk mapping as the first step in a $20 million cost-shared program. Other sub-agreements may be developed subsequently to deal with forecasting, flood-proofing and property acquisition or easements. Six pilot projects on flood-risk mapping are in various stages of completion across the country.

Floods are natural events that occur fairly frequently on virtually all streams; often, they are the most destructive hazard in the world. Hydrologically, a flood occurs when the drainage basin experiences an unusually intense or prolonged water input event and the resulting discharge exceeds the channel capacity or the capacity of the reservoirs.

Uncertainty in design discharge, known as a hydrologic uncertainty, is usually determined by hydrologic analysis by frequency analysis or by rainfall-runoff modelling. The problem of transforming the design discharge into a flood stage and evaluating its risk is a crucial one for flood risk mapping. It can be solved by applying the advanced first-order second moment (AFOSM) method [1,6]. This operation should also consider the hydraulic uncertainty, which is usually neglected. Hydraulic uncertainty results from different sources, according to its components and can be classified as: (1) the model formulation uncertainty, (2) the geometry of the structure uncertainty and (3) the model parameter uncertainty.

The runoff formation process is believed to be highly non-linear, time varying, spatially distributed, and not easily described by simple models. Considerable time and effort has been spent to model this process, and many hydrologic models have been built specifically for this purpose. These models are generally known as a rainfall — runoff (R-R) models.

The political and socio — economic transformation of the social systems in the Central and Eastern European countries at the beginning of the 1990s was also reflected in the sector of potable water supply. This transformation underwent various kinds of development in various countries depending on local conditions, pace of economic transformation, development of the legislation, interest of foreign entities and international institutions, and involvement in the European integration process.

The Prague Water Supply and Sewerage Company (PVK) is owned by the French company Vivendi Water (66% of shares). The remaining 34% of the shares was given (free) to the City of Prague. PVK was established on the 1st April 1998 as a legal successor of the state companies Prague Waterworks and Prague Sewerage and Watercourses as part of the privatisation project. PVK is the operator of the water management infrastructure in Prague. The administrator is the Prague Water Management Company, the founder and maj or owner of which is the City of Prague.

The requirements of The Water Supply Centralized Systems in Romania (SCAA) result from the identification and analysis of the causes of dysfunctionality and deficiencies, which are found in installations, equipment functions and operation, and also in water companies management.

The network of distribution mains is nearly the most expensive item of equipment in a water undertaking. Also, the cost of its upkeep generally represents a large proportion of the annual maintenance budget. It is therefore the duty of water engineer to devote some considerable care to the design of the most efficient distribution system and this entails accurate prediction of the discharges and pressures in the various pipe components.

The primary functions of a conventional CSO include the following: — to act as a hydraulic control on the system and to restrict the continuation flow to the downstream sewer to the setting,— to provide a relief overflow to allow the spill (usually to the nearest watercourse) of any inflow having a magnitude greater than that of the setting,— to prevent flooding in the upstream catchment,— to be efficient in the retention of solids and associated pollutants for treatment and to create a flow pattern within the chamber that is conducive to the separation and retention of gross and finely suspended solids, and— to be self-cleansing and maintenance free by avoiding blockage and complication in design.

The Urban Wastewater Treatment Directive (UWWTD) requires EC member states to take action to limit pollution from storm overflows and to improve unsatisfactory intermittent wet weather discharges from combined Sewer Overflows (CSOs) and stormtanks at wastewater treatment plants. While there are no specific European requirements, such wet weather intermittent discharges can also contribute to failures to meet standards set by other Directives, such as the Fishery, Bathing Water and Shellfish Waters Directives.

Urban wastewater systems (UWWS) consist of three main sub-systems: the urban drainage network, the wastewater treatment plant (WWTP) and the receiving water. Recent research has shown the potential benefits of considering the three systems as one entity [1,2] when striving to achieve stringent water quality standards. This has become possible due to the better understanding of the systems and improvements in computer modelling of the integrated system. The particular benefit of modelling the integrated system is that the dynamic and multifaceted interactions between the individual sub-systems can be investigated and the impact of the whole system on the river water quality can be determined.

In most cases, sewers and wastewater treatment plants were, and still are, designed and operated based on an empirical approach that takes into account a fixed level of permissible discharge into receiving water bodies. According to the “old” empirical rules -that are nevertheless still applied unchanged at a large number of facilities-, the fraction of incoming flow exceeding the maximum design flow (usually 2–6 times the average dry weather flow, depending on local regulations) is diverted to the receiving waters without treatment, in order not to “upset” the ongoing biological processes.

Wastewater sludge treatment and disposal have always created more problems than wastewater treatment itself. This is rooted in the fact that in contrast to wastewater, which continuously passes through the wastewater treatment plants (WWTPs) without affecting (in quantitative sense) the natural hydrological cycle, sludge is entirely accumulated there. Due to its specific properties, the accumulated sludge inclusion in the natural cycles of mass transfer “in an economically and environmentally acceptable manner” [14] is more difficult. This is because sludge management is associated with overcoming serious technological and economical problems, some of which have not received satisfactory solution as yet. Biological stabilisation of municipal wastewater sludge is one of them, irrespectively of the availability of significant experience and the long historical development of this issue.

Pollutants in municipal sewage include a complex mixture of soluble and insoluble constituents ranging in size from less than 0.001 μm up to over 100 μm [1]. Several studies have been addressed to the classification of contaminants in wastewater in terms of particle size. Balmat [2], Heukelekian and Balmat [3] and Rickert and Hunter [4], using a sequence of sedimentation, centrifugation and filtration, separated the contaminants into four size fractions: settleable (> 100 μm), supracolloidal (1–100 μm), colloidal (0.08–1 μm), and soluble (< 0.08 μm). On the basis of a sequential filtration of the wastewater, Munck et al. [5] used a slightly different definition of the four size ranges: settleable (> 106 μm), supracolloidal (3-106 μm), colloidal (0.025–3 μm), and soluble (< 0.025 μm). Notwithstanding the differences in the operating definition of the size ranges, these studies do agree that only a quarter or less of the COD of the raw sewage may be considered truly soluble [6]. The majority of the pollutant load is actually in suspended form, and is not easily biodegradable. In addition, other contaminants, such as heavy metals, bacteria and viruses, and organic micro pollutants (PCB, PAH) are strongly associated with the suspended phase.

It is recognised that planning, design and operation of urban water systems constitutes a complex task. Even when only the wastewater part of the urban water system is considered, the management of this system remains a challenging task. In the past and, in many instances still today, sewer system, wastewater treatment plant and receiving water bodies -as the main constituent subsystems of the urban wastewater system (UWWS) — are considered often only as separate entities with little or no interaction. In order to support the tasks of planning, design and operation of wastewater systems and to achieve the objectives, such as the protection of health, mitigation of floods, prevention of pollution and reduction of costs to name but a few, simulation models have been developed over the years. In particular, since the advent of easily accessible computing capacity, computer models have been increasingly used in research and practice.

The area of water utilities is subjected to a large dynamic development, caused by changes in social, ecological, legislative and economic environments and by the current technical achievements (Fig.1). A growing complexity of tasks, a long-term management and planning in this area demand an increasing amount of actual and correct information being supported by the modem information technology. The information gradually gains a new role in urban drainage and water supply management. It becomes as important source as the other financial, human or physical sources. The information is approached as a special kind of goods having its value or market price. The needs for information sources, the quality, storage, evaluation, transfer, access, etc., as well as financial and property questions then come to light in relation with the growing importance of information and its symbolic representation — data.

Role and function of surface water in cities and towns are well known and indisputable: — water resources are among main factors of cities development;— water surfaces are important media for transport;— water bodies are important climate regulation factors (especially during hot and dry periods);— water bodies are used as recreation areas, etc.

The Water Protection of the Dyje River Basin Project- hereafter referred to as the Dyje Project — has the following goals: — To ensure that waste water treatment and the quality of water discharged into the Dyje River meets the standards of the Urban Waste Water Treatment Directive 91/ 271 /EEC as amended by Directive 98/15/EC and;— To ensure suitable waste water treatment and sewerage for 10 agglomerations in the Dyje River Basin in accordance with Chapter 22 Environment — Implementation Plan for subchapter D — Water Quality and the results of negotiations on this chapter as recorded in the EU Common Position (CONF-CZ 28/01);— To ensure financing of the project combining EU ISPA funding, Czech government and municipality funding.

General environmental problems in the Lielupe River Basin since many years have been: (a)Transboundary pollution from Lithuania (big cities are situated on banks of small rivers and a big amount of wastewaters violate self-cleaning ability in rivers).(b)Diffuse pollution, mainly contributing to eutrophication, since a big part of Lithuanian catchments and region Zemgale in Latvia are high-developed agricultural areas with intensive agricultural production.(c)Pollution from point sources, caused by inadequate and insufficient treatment of wastewaters.(d)Modifications of rivers due to land reclamation.(e)Poor biodiversity of river fauna in practically whole watershed.(f)Drinking water doesn’t meet requirements due to local natural peculiarities of groundwater and/or poor condition of pipelines and inappropriate farming practices.(g)Only a few landfills have facilities to treat leachate or are connected to a sewerage system.

Bulgaria is not rich in water resources compared to other European countries. Depending on the rainfall in a given year, 9 to 24 billion m3 are formed every year. The average amount per capita is approximately 2,300 – 2,500 m3 per year. This puts Bulgaria, together with Poland, the Czech Republic, Belgium and Cyprus, among the poorest European countries in terms of water resources.

Water is the most important foodstuff in the world. Access to water is essential for all life. We must have water to drink and water is required to cultivate other basic foodstuffs. In order for everyone to have access to water, regardless of the quality of life, it has to be supplied at the lowest possible cost and be of acceptable quality.

The purpose of this paper is to provide the reader with further insight into the methodology being adopted by Sofiyska Voda AD (S V) in tackling the issues currently facing the Company. In particular, the paper focuses on how SV plans to set up an optimised approach to the management of its assets.