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Impact of Combined Sewer Overflows Events on Recipient Water Quality
Abstract
This chapter analyses the impacts of discontinuous pollution sources on the water quality of receiving water bodies and offers the possibility to solve such type of water management problem by numerical modelling way. Typical examples of such pollution sources are the combined sewer overflows (CSOs), but generally also different types of storm water management in urban areas. There were designed and performed numerical simulations for four feasible alternatives of storm sewer management (different mixing ratio, different size of storm tanks) in the town Banská Bystrica at the Hron River (Slovak republic). The model MIKE11 was used for numerical simulations of water quality. Results of each modelled alternatives were analysed. Simulation was performed in two alternatives – for Qa and Q355, whereas Qa is the yearly average discharge and Q355 is a discharge, which exceeded 355 days in a year. Results of the study show practical implications and impacts on the receiving water body quality depending on the type of the storm water management.
The recent advances in current status and major mechanisms of water quality worsening, assessment of evaluation criteria and the influencing factors were reviewed. The changes in the atmosphere, the periodicity of the occurrence of extreme hydrological situations has been increasing in recent years. In the natural conditions of Slovakia, periods without rain are lengthening and the incidence of precipitation of extreme intensity and abundance is increasing. Hydrological extremes are generally manifested in the form of floods and droughts. The increased incidence of drought is a new phenomenon. The analysis was conducted using a long series pH and temperature measurements. The pH, temperature and conductivity are the most important water quality parameters. Their time-series were used for investigation of pH with regard to the place of collection and seasonal cycle. The pH ranged from 5 to 9, i.e. predominantly in the alkaline area. Average value of pH in the monitored period 2010-2020 was 7.56, One of the most important tools for evaluating water quality and character in a catchment is a detailed knowledge of the ranges and trends in pollution of natural water. This requires water accounting be conducted at the regional scale.
The article is focused on analysis of input data impact on outputs of water quality models. The authors examined the impact of roughness coefficient, both boundary and initial conditions setup on changes of outputs generated by HEC-RAS model. Simulation results have shown a various response rate of input data on simulated results. The strong impact shows roughness coefficient setup that through the value of longitudinal dispersion coefficient affects pollution transport process. Changes in boundary conditions have had less influence on outputs. Relatively strong impact shows the setup of initial state of pollution concentration along the reach mainly for the case of low gradient rivers.
Human excessive requirements on functions of aquatic ecosystems cause that surface waters often suffer from significant morphological and hydrological alterations. Human induced hydromorphological changes of rivers belong among the most common ecological problems of the water bodies and they appear in all scales of river habitat. These changes have an impact in their ecological status and need to be solved in the near future. Successful sustainable river rehabilitation depends on the identification and understanding of key processes and anthropogenic stressors. These factors enable to estimate a proper longitudinal and lateral riverine system structure including stream habitat improvements at different scales. The article summarizes the basic principles of urban river restoration, that enables to approach to the state of dynamic stability and to increase the "absorbing capacity" of freshwater ecosystem. The authors also provide the background facts and principles of the restoration design of canalized reach of the River Trnavka, which flows through an urbanised part of the city Trnava. The Trnavka River has regulated flow regime affected by operation of Boleraz reservoir located 14 km in upstream direction. The river channel capacity equals to 50 m³.s⁻¹ with return period 100 years and ecological flow is Q=0,150 l.s⁻¹. The heavily modified nonprismatic channel has stone and concrete stream banks. The authors have proposed increasing sinuosity of low flow channel and decreasing capacity of the oversized channel by using gravel matraces with planting different types of macrophytes. The main goal of the proposed river restoration measures was to increase aesthetic value of complex restoration design of close public space (the Rose Park) and to implement technical and biotechnical measures that may improve ecological conditions and management operation of the Trnavka River.
Introduced in 2000 to reform and rationalise water policy and management across the European Union (EU) Member States (MS), the Water Framework Directive (WFD), the EU's flagship legislation on water protection, is widely acknowledged as the embodiment and vessel for the application of the Integrated River Basin Management (IRBM) paradigm. Its ecological objectives, perhaps even more challenging than the prospect of statutory catchment planning itself, were for all EU waters to achieve 'good status' by 2015 (except where exemptions applied) and the prevention of any further deterioration. In support of the upcoming WFD review in 2019, the paper reviews the transition of EU policies that led to the adoption of the WFD, to identify the reasons why the Directive was introduced and what it is trying to deliver, and to place progress with its implementation into context. It further investigates reasons that might have limited the effectiveness of the Directive and contributed to the limited delivery and delays in water quality improvements. Findings reveal that different interpretations on the Directive's objectives and exemptions left unresolved since its negotiation, ambiguity and compromises observed by its Common Implementation Strategy and lack of real support for the policy shift required have all been barriers to the harmonised transposition of the IRBM paradigm, the key to delivering good ecological status. The 2019 WFD review offers a unique opportunity to realign the implementation of the Directive to its initial aspirations and goals.
The modelling of pollution transport processes in open channels requires good knowledge about parameters such as hydrodynamic dispersion, advection and decay rates. These parameters can be determined by tracer studies. The basic output of these studies takes the form of observed time course data for the concentration of injected tracer in sampling profiles. In this study, Rhodamine WT fluorescein dye was used as a tracer. The travel time of the front and tail of the dye cloud and the magnitude of the peak concentration can be additionally derived. Two dye tests were carried out at the Svitava and Svratka rivers in the Czech Republic. These are rivers which are mostly regulated and feature widths ranging from 10 to 25 m. Data were collected from 4 and 5 sampling profiles, respectively, along 16.1-km-long reaches of the rivers. The transport parameters were derived via inverse numerical analysis of the collected data and were compared with values obtained by previously published empirical formulas based on dimensional analysis. The resulting dispersion coefficient was from 7.2 to 9.5 m2/s and showed good agreement with previous studies.
The aim of the paper is to study spatial and temporal changes in the magnitude, duration and frequency of high flows in the Danube basin. A hydrological series of the mean daily discharges from 20 gauging stations (operated minimally since 1930) were used for the analysis of changes in the daily discharges. The high flow events were classified into three classes: high flow pulses, small floods, and large floods. For each year and for each class, the means of the peak discharges, the number and duration of events, and the rate of changes of the rising and falling limbs of the waves were determined.
The long-term trends of the annual time series obtained were analyzed and statistically evaluated. The long-term high flow changes were found to be different in three individual high flow classes. The duration of the category of high flow pulses is decreasing at 19 stations on the Danube and is statistically significant at the Linz, Vienna, Bratislava and Orsova stations. The frequency of the high flow pulses is increasing in all 20 stations. Also, the rising and falling rates of the high flow pulse category are increasing at the majority of the stations. The long-term trends of the selected characteristics of the small floods are very similar to the trends of the high flow pulses, i.e., the duration of small floods is decreasing, and their mean number per year is increasing. In the category of large floods the changes were not proved.
The aim of this document is to present a synthesis of water sustainability issues as the basic role in the sustainable growth strategies in many countries. Water crisis and extreme weather conditions have been identified by the World Economic Forum community as two of the top ten global risks. This is hardly surprising, considering the devastating impacts of having too little water, or too much. While water’s immediate impacts are often local, water security is now recognized as the systemic global risk. Each development has its own limiting parameters. In the latest decades, we have recognized the term ‚blue and green water‘. Blue water availability is a limiting factor for the green water. Due to the changes and processes in the country, as climatic, economic or socio-economic ones, fundamental factor for sustainable development is to secure water supply. Soil water and its availability for crop production during the growing season appear to be a problem. Surface water resources created for the additional irrigation in the pastures are now used for other purposes such as energy or industry. It is therefore important for water sustainability in the countries to increase the water resources protection.
The article analyses dependence of water quality parameters on flow rates in several profiles in the Vltava River catchment in the Czech Republic in the period 1997 - 2013. In study, influence of low flow rates on the water quality is assessed on several examples of river profiles, tributaries and outflow of the Orlík Reservoir, which is located at the Vltava River in the Czech Republic. At these sites, we monitored changes in general parameters of the water quality - temperature (T), pH, dissolved oxygen (O2), chemical oxygen demand permanganate (CODMn), chemical oxygen demand dichromate (CODCr), biochemical oxygen demand (BOD5) a suspended solids (SS), nutrients – nitrate nitrogen (N-NO3-), ammonia nitrogen (N-NH4+), total phosphorus (PT) and phosphate phosphorus (P-PO43-) and further quality parameters – dissolved solids (DS), dissolved inorganic salts (DIS), calcium (Ca2+), magnesium (Mg2+), potassium (K+), chlorides (Cl-), sulphates (SO42-) and qualitatively also non-polar extractive substance (NES) a anion-active surfactants. The assessed period was 1997-2013. Aim of the study was to evaluate relationship between mentioned parameters and the flow rates in days, when the samples were taken. Furthermore, ratios of average parameters values during low and high flows were calculated.
The results show that in the monitored profiles, there is a direct relationship with flow rate in case of N-NO3-, suspended solids and O2. Temperature shows an inverse relationship with the flow rate. Other parameters show different relationship with the flow rate in individual monitored profiles or do not show statistically significant relation.
During the past decades, several models that predict the concentration profiles after a discharge of pollutants in a river have been developed. A model that predicts nitrogen concentrations in a river has been developed and is presented in this paper. The developed model that determines nitrogen concentrations in a water stream is based on a dimensional analysis. Fundamentals of the modelling of the pollutant predictions in a water stream consist of a derivation of function dependency from expressed non-dimension arguments. Non-dimension arguments are stated from variables, which influence the occurrence of pollutants. The model for the prediction of nitrogen concentrations in water streams has been developed for the Laborec River (eastern Slovakia). The differences between the nitrogen concentrations predicted from developed models and measured concentrations in the river are also discussed here.
The present research has two main objectives (1) to build two models for concentration prediction in a stream subject to a pollutant release and (2) to investigate options for estimating the parameters of the models. The models rely on the fundamental advection–dispersion equation and were developed, calibrated and evaluated using tracer data from experiments conducted in the Murray Burn in Edinburgh, UK. During the evaluation by comparison against field data both models were able to predict the main features of the observations at the first three monitoring sites, but results at the final site were less good.These types of models rely very much on the ability to make good estimates of velocity and dispersion coefficients along the stream. Although these parameters could be estimated using tracer experiments, it would be easier if they could be estimated from other hydraulic data such as the water flow rate and the channel characteristics. For the Murray Burn such models for parameter estimation were developed in the form of non-linear relationships with flow rate. This approach could be used to calculate the parameters for other similar streams, if the coefficients in the equations were similar. Alternatively, further work would be needed to explore how these coefficients vary between streams.
The increased pollution of water resources leads to a deterioration in the quality of surface water and groundwater, and it initiates the application of various methods for water treatment. The Slovak Technical Standards – STN 75 7111 Water – and the enactment of the Decree of the Ministry of Health of the Slovak Republic No. 151/2004 on requirements for drinking water and monitoring of the quality of drinking water quality have resulted in the reduction of heavy metal concentrations or, for the first time, in defining the limit concentrations for some heavy metals (As, Sb), respectively. Based on this fact, some water resources in Slovakia have become unsuitable for further use, and they require appropriate treatment. The objective of the study was to verify the sorption properties of some new sorption materials for the removal of antimony (Bayoxide E33, GEH, CFH12). Technological tests were carried out at the facility of the Slovak Water Company Liptovský Mikuláš in the locality of Dúbrava. Technological tests have proved that the new sorption materials can be used for reduction of antimony concentration in water to meet the values set under the Decree of the Ministry of Health of the Slovak Republic No. 247/2017 on requirements for drinking water – 5 μg/L.
The paper describes a process of implementing sustainable stormwater management in the Czech Republic, including motivations behind the process, the situation in stormwater management before the implementation, actions undertaken during the preparation of a national stormwater concept, obstacles and the current status of implementation. The first large scale pilot study is given as an example of the process and lessons learned are summarized in order to give the experience to other countries.
The paper introduces basic principles of a new Czech technical standard in the field of stormwater management (TNV 75 9011 Sustainable Stormwater Management). It describes the procedure of the selection of the drainage concept, when individual approaches (stormwater infiltration
, drainage to the surface waters, drainage by the combined sewer system) have to be subsequently examined as to their admissibility and feasibility. Within the detailed drainage design, focus is put on the hydraulic loading of infiltration devices determining their pollutants removal efficiency and on the stormwater pre-treatment techniques suitable for the removal of individual pollutant categories before infiltration or discharge to the surface waters. The standard gives also an overview of stormwater management structures and devices together with the rules for their technical and hydraulic design, construction, operation and maintenance.
There exist proofs that the global warming, which is happening since the industrial revolution, is the consequence of the greenhouse emissions increase caused by the human activity. The development of computer models, besides the increasing evidences about the rising temperatures, and the more frequent weather variation are in accordance with the scientist’s predictions about the climate change. The modelling tools also showed that in the twenty-first century temperatures can increase hereafter and influence the nature and the human being.
Design and operation of urban drainage systems are addressed in the context of the urban water system comprising drainage, sewage treatment plants and receiving waters. The planning and design of storm sewers are reviewed with reference to planning objectives, design objectives, flows and pollutant loads, sewer system structures and urban runoff control and treatment. The discussion of combined sewers focuses on hydraulic design of combined sewer systems, including combined sewer overflow (CSO) structures, and the use of CSO structures and storage in control of CSOs. The section on operation of sewer systems focuses on real time control, its feasibility, planning, design, operation and applications. Sewer system planning and design are generally conducted using computer modelling tools and procedures which are reviewed in the last section. A brief listing of selected models focuses on internationally used models. Finally, it was concluded that further improvements in environmental and ecological protection of urban waters is feasible only by consideration of urban drainage systems in conjunctions with sewage treatment and water quality in the receiving waters.
Combined sewer systems in Slovakia were evaluated during a three-year joint research project of the Water Research Institute and the Department of Sanitary Engineering of the Slovak University of Technology. First results of the comprehensive assessment are presented in the paper. Over 300 combined sewer overflows (CSOs) were visited and their structural condition evaluated. Samples of overflowing water were taken from eight overflows and analysed for common constituents. A water quality database was prepared from the CSO pollution data. The first flush of organic pollution was not confirmed in any of the events.
MIKE 11 User manual, Version
- Dhi
Topographics maps 1:50 000. Military Topographic Institute (MTI)
- Mti
Urban river design: a river restoration case study
- D Halajová
- P Halaj
- V Macura
- A Škriniar
establishing a framework for community action in the field of water policy (EU water framework)
- Wfd
Water resources in Slovakia: part I. The handbook of environmental chemistry
- J Ilavský
- D Barloková
Changes in water management strategy as a way for increasing of agro-ecosystems resilience towards drought
- V Bárek
- P Halaj
- J Fuska
- D Halajová
- A Báreková
Water management map of Slovak republic 1:50000. Water Research Institute (WRI)
- Wri
Directive 2008/105/EC of the European Parliament and of the council of 16 December 2008 on environmental quality standards in the field of water policy
- Ewqsd
Examination of the geomorphologic and hydrodynamic parameters of river Hron. (in Slovak)
- M Mišík
Longitudinal dispersion coefficient in natural streams
- D Halmová
- P Miklánek
- J Pekár
- B Pramuk
- P Pekárová