Dissertations / Theses on the topic 'Water quality modelling'
To see the other types of publications on this topic, follow the link: Water quality modelling.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Water quality modelling.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Maier, Stefan Heinrich. "Modelling water quality for water distribution systems." Thesis, Brunel University, 1999. http://bura.brunel.ac.uk/handle/2438/5431.
Full textAbstract:
Maintaining water quality in distribution systems has become a prominent issue in the study of water networks. This thesis concentrates on disinfectant and particle counts as two important indicators of water quality. The models discussed in this work are based on data collected by the author. The experimental set-up and procedure are described and observations of particle counts, particle counter size distributions, monochloramine as disinfectant, temperature, heterotrophic plate counts and epifluorescence microscopy counts are reported. A model of the response of particle counts to an increase in flow is developed. This model is obtained from specification derived from the data and assumptions, and is validated by its interpretability and its fit to data. A local shear-off density and an initial biofilm shedding profile were introduced and thus a linear model for this part of the water quality dynamics could be obtained. A procedure for the identification of the parameters of the local shear-off function and for the determination of the biofilm shedding profile is presented. This profile can be used to provide information about the status of the distribution system in terms of shear-off from the biofilm on the pipe walls. Monochloramine decay dynamics are investigated. The chlorine meter data is preprocessed with the help of titration data to correct meter drift. The data is then used in calibrating two different possible chlorine models: a model with a single decay coefficient and a model with bulk decay coefficient and wall demand (as used in Epanet). Important difficulties in identifying these parameters that come about because of the structure of the models are highlighted. Identified decay coefficients are compared and tested for flow, inlet chlorine and temperature dependence. The merits and limits of the approach to modelling taken in this work and a possible generalisation are discussed. The water industry perspective and an outlook are provided.
2
Machell, John. "Water quality modelling in distribution networks." Thesis, University of Sheffield, 2004. http://etheses.whiterose.ac.uk/14849/.
Full textAbstract:
The thesis is a treatise of the quantity and quality aspects of potable water in distribution systems. The privatisation of the UK Water Industry in 1989 has seen the requirement for the Water Companies in England and Wales to be responsible for the delivery of good quality water that meets the demand of all consumers. In respect of the quantity of supply, there have been many previous studies that have examined the hydraulic performance of distribution systems and there are now many proprietary mathematical models that have been successfully used in this study. However, in respect of water quality the literature review has highlighted that the modelling approach is not so well advanced, as water quality is a function of many concepts, processes and parameters that include the source and age of water, the condition and deterioration of the assets in the system, the microbiological, chemical and physical processes and the network hydraulic performance, including pressure transients. These processes are highly interactive and complex. In an attempt to better understand these processes a programme of research has been completed that has involved a field evaluation of the performance of a live system, including the development of instrumentation to continually measure water quality, and the development of a mathematical model to describe the processes associated with the age of water and the propagation of conservative and non-conservative substances. An initial attempt has also been made to develop a micro-biological model and a sediment transport model. New original concepts developed by the author include age, biological and diagnostic models that may be used to identify the source of any incident (hydraulic or pollution) and the application of the model in near real time.
3
Jacobs, Haden. "Modelling water quality : complexity versus simplicity." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/4754.
Full textAbstract:
Water quality management makes use of water quality models as decision making tools. Water quality management decisions need to be informed by information that is as reliable as possible. There are many situations where observational data are limited and therefore models or simulation methods have a significant role to play in providing some information that can be used to guide management decisions. Water quality modelling is the use of mathematical equations and statistics to represent the processes affecting water quality in the natural environment. Water quality data are expensive and difficult to obtain. Nutrient sampling requires a technician to obtain ‘grab samples’ which need to be kept at low temperatures and analysed in a laboratory. The laboratory analyses of nutrients is expensive and time consuming. The data required by water quality models are seldom available as complete datasets of sufficient length. This is especially true for ungauged regions, either in small rural catchments or even major rivers in developing countries. Water quality modelling requires simulated or observed water quantity data as water quality is affected by water quantity. Both the water quality modelling and water quantity modelling require data to simulate the required processes. Data are necessary for both model structure as well as model set up for calibration and validation. This study aimed to investigate the simulation of water quality in a low order stream with limited observed data using a relatively complex as well as a much simpler water quality model, represented by QUAL2K and an in-house developed Mass Balance Nutrient (MBN) model, respectively. The two models differ greatly in the approach adopted for water quality modelling, with QUAL2K being an instream water quality fate model and the MBN model being a catchment scale model that links water quantity and quality. The MBN model uses hydrological routines to simulate those components of the hydrological cycle that are expected to differ with respect to their water quality signatures (low flows, high flows, etc.). Incremental flows are broken down into flow fractions, and nutrient signatures are assigned to fractions to represent catchment nutrient load input. A linear regression linked to an urban runoff model was used to simulate water quality entering the river system from failing municipal infrastructure, which was found to be a highly variable source of nutrients within the system. A simple algal model was adapted from CE-QUAL-W2 to simulate nutrient assimilation by benthic algae. QUAL2K, an instream water quality fate model, proved unsuitable for modelling diffuse sources for a wide range of conditions and was data intensive when compared to the data requirements of the MBN model. QUAL2K did not simulate water quality accurately over a wide range of flow conditions and was found to be more suitable to simulating point sources. The MBN model did not provide accurate results in terms of the simulation of individual daily water quality values; however, the general trends and frequency characteristics of the simulations were satisfactory. Despite some uncertainties, the MBN model remains useful for extending data for catchments with limited observed water quality data. The MBN model was found to be more suitable for South African conditions than QUAL2K, given the data requirements of each model and water quality and flow data available from the Department of Water and Sanitation. The MBN model was found to be particularly useful by providing frequency distributions of water quality loads or concentrations using minimal data that can be related to the risks of exceeding management thresholds.
4
Braga, Maria Cristina Borba. "Surface water quality modelling of mercury contamination." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396307.
Full text
5
Sherwood, Julia M. "Modelling minewater flow and quality changes after coalfield closure." Boston Spa, U.K. : British Library Document Supply Centre, 1997. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.363536.
Full text
6
McIntyre, Neil Robert. "Analysis of uncertainty in river water quality modelling." Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/11828.
Full text
7
Sincock, Andrew Michael. "Conceptual river water quality modelling under dynamic conditions." Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/11912.
Full text
8
Newham, Lachlan Thomas Hopkins, and lachlan newham@anu edu au. "Catchment Scale Modelling of Water Quality and Quantity." The Australian National University. Centre for Resource and Environmental Studies, 2002. http://thesis.anu.edu.au./public/adt-ANU20050919.144548.
Full textAbstract:
Appropriately constructed pollutant export models can help set management priorities for catchments, identify critical pollutant source areas, and are important tools for developing and evaluating economically viable ways of minimising surface water pollution.¶
This thesis presents a comparison, an evaluation and an integration of models for predicting the export of environmental pollutants, in particular sediment, through river systems. A review of the capabilities and limitations of current water quality modelling approaches is made. Several water quality and quantity modelling approaches are applied and evaluated in the catchment of the upper Murrumbidgee River.¶
The IHACRES rainfall-runoff model and a simple hydrologic routing model are applied with the aim of developing a capacity to predict streamflow at various catchment scales and to enable integration with other pollutant load estimation techniques. Methods for calculating pollutant loads from observed pollutant concentration and modelled streamflow data are also investigated. Sediment export is estimated using these methods over a 10-year period for two case study subcatchments. Approaches for water quality sampling are discussed and a novel monitoring program using rising stage siphon samplers is presented.
Results from a refinement of the Sediment River Network model in the upper Murrumbidgee catchment (SedNet-UM) are presented. The model provides a capacity to quantify sediment source, transport and to simulate the effects of management change in the catchment. The investigation of the model includes rigorous examination of the behaviour of the model through sensitivity assessment and comparison with other sediment modelling studies. The major conclusion reached through sensitivity assessment was that the outputs of the model are most sensitive to perturbation of the hydrologic parameters of the model.¶
The SedNet-UM application demonstrates that it is possible to construct stream pollutant models that assist in prioritising management across catchment scales. It can be concluded that SedNet and similar variants have much potential to address common resource management issues requiring the identification of the source, propagation and fate of environmental pollutants. In addition, incorporating the strengths of a conceptual rainfall-runoff model and the semi-distributed SedNet model has been identified as very useful for the future prediction of environmental pollutant export.
9
Kamish, Wageed. "Hydrosalinity modelling of the Berg River using ACRUSalanity /." Link to the online version, 2008. http://hdl.handle.net/10019/2022.
Full text
10
Goodhue, Nigel David. "Hydrodynamic and water quality modelling of the lower Kaituna River and Maketu Estuary /." The University of Waikato, 2007. http://hdl.handle.net/10289/2375.
Full textAbstract:
The Maketu Estuary is a shallow intertidal estuary (2.3 km2) located in the Bay of Plenty, North Island, New Zealand. The Kaituna River contributes the largest freshwater flow into the estuary through control gates. Lake Rotoiti and indirectly Lake Rotorua supply the base flow to the Kaituna River, with tributaries along the 50 km reach also significantly contributing to the flow. Water quality within the river is affected by elevated nutrients, faecal coliforms, high oxygen demand and algae concentrations derived from the lakes as well as contributions from tributaries and industrial and urban discharge. Through the use of a coupled hydrodynamic-biogeochemical numerical model ELCOM-CAEDYM, this study aims to examine the nutrient, phytoplankton and hydrodynamics of the Maketu Estuary and lower Kaituna River. Water quality and hydrodynamic measurements were sourced from Environment Bay of Plenty's data archives as well as a number of instrument deployments to collect water velocity, tidal elevation and salinity and temperature measurements during the course of this study. Included in the field work was a survey of the lower river and estuary bathymetry. Model simulations predicted that the maximum residence time in the Maketu Estuary is 1.5 days, occurring in the inner western region. Residence time in the lower river (mouth to 8.5 km upstream) is in the order of hours although some variations were predicted near the river mouth. Growth rates of four phytoplankton groups where assessed over a 15 day period in January 2004. In the Kaituna River ELCOM-CAEDYM predicted that the community growth rates were small with the exception of a slight increase in biomass of the two freshwater groups in a semi-detached river bend. The increase in the loop was correlated with an increase of residence time. In the estuary, marine diatoms showed the highest growth rates in the western region which is expected to relate to retention time and available nutrients. Dinoflagellates showed the smallest variation in predicted growth rates, most likely due to their broad salinity tolerance. The two freshwater species showed a reduction in abundance when mixed with marine water. A principle limiting factor to phytoplankton growth in both the river and estuary is the low residence time. A number of scenarios were simulated in the river and estuary by altering the forcing conditions in the model. A simulation of the increased nutrient load associated with the Rotoiti diversion wall revealed that phytoplankton growth in the river and estuary will not be significantly affected. Because of the close proximity of the control gates to the river mouth, a proportion of water drawn through the structure can be marine. By opening the old river channel, model simulations predicted that a reduction in salinity would be possible, however the outcome of complete freshwater is probably not achievable. Increasing the discharge volume from the river into the estuary was also simulated. The results indicated that increasing the freshwater inflow at Fords Cut would reduce the salinity in the estuary while increasing the net (residual) flow towards the estuary mouth. Increasing the flow would also result in a greater range of salinity in regions of the estuary. Changing the inflow location to the historic Papahikahawai Channel also affected the salinity in the estuary. The most significant effect of an inflow at this location was a reduction of the residual currents in the western region of the estuary.
11
Birkinshaw, Stephen J. "Nitrate transport component for SHETRAN catchment modelling system." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336759.
Full text
12
Tyrrell, Deborah Ann. "Modelling the water quality of the Patos Lagoon, Brazil." Thesis, University of Plymouth, 2005. http://hdl.handle.net/10026.1/1737.
Full textAbstract:
A two-dimensional depth integrated finite element modelling suite comprising the flow model TELEN4AC-2D and the water quality model WQFLOW-2D has been calibrated to simulate the physics and chemistry of the Patos Lagoon and Estuary system in southern Brazil for the investigation of nutrients, primary production and faecal bacteria. The model has been evaluated for use as a predictive tool to aid the decision making process for the rehabilitation and management of the shallow embayment of Saco da Mangueira adjacent to the city of Rio Grande in the lower Patos Estuary. This bay is one of several shallow areas bordering the city which suffers from the water quality pollution problems associated with eutrophication due to the influence of multiple and conflicting human impacts including the disposal of waste water from domestic and industrial sources such as the fertiliser industry, fish processing, and petroleum refining. The validated flow model indicated a very weak circulation in the Saco da Mangueira with velocities an order of magnitude lower than in the estuary. Simulations conducted to evaluate transport and mixing time scales demonstrated limited water exchange between the bay and the estuary principally controlled by wind direction and duration, with efolding flushing times between 21 and 45 days using observed wind and river flow data. The water quality modelling undertaken in this research represents the first reported application of WQFL0W-2D to the Patos lagoon and estuary system, and the first water quality modelling exercise of any kind reported to date for the Saco da Mangueira. Calibration and validation processes demonstrated that WQFLOW-2D could simulate annual average observed concentrations of water quality variables consistently and confirmed the eutrophic nature of the waters within the Saco da Mangueira. The model was used as a comparative tool to evaluate the predicted performance of hypothetical engineering schemes designed to improve the water quality within the bay and water exchange at the mouth. A number of recommendations were made including an imperative requirement for the collection of pollutant input and process data to reduce the level of uncertainty associated with the water quality model.
13
Venter, Ansie. "Water quality modelling of eutrophied reservoirs in South Africa." Doctoral thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/9469.
Full textAbstract:
Includes bibliography.Governmental agencies in South Africa became concerned about the increase in eutrophication-related water quality problems during the early 1970's. The first step taken to control eutrophication was introduction of an effluent phosphate standard that limited the phosphorus concentration in effluents being discharged in certain sensitive catchments to a maximum of 1 mg P04-P 1-1. This standard applied only to point sources, because of an initial belief that the contribution from non-point sources was relatively minor, and the absence of practical economic measures to control phosphorus discharges from non-point sources. Subsequent to introduction of the 1 mg P Standard several modelling studies were undertaken, as there was a need to describe the response of eutrophic reservoirs to altered phosphate inputs. Most of the work was done on the hypertrophic Hartbeespoort Dam reservoir. The models utilised were empirical, zero-dimensional models that treated the reservoir as a completely mixed reactor. Usually these models considered only the steady state, or at most, annual changes. The models simulated annual mean phosphate-P concentrations with varying degrees of success, but a significant relationship between observed and simulated chlorophylla concentrations could not be obtained, i.e. these models could not be used to predict the response of eutrophic reservoirs to different management strategies aimed at alleviating eutrophication-related water quality problems. Consequently, a further study was initiated by the Water Research Commission to test the applicability of more sophisticated hydrodynamic and water quality models, developed in the USA and Australia, to stratified reservoirs under South African climatic conditions. Several models of varying complexity were available. From these four models were selected for study. The models that were tested were the one-dimensional models DYRESM (developed in Australia), and MINLAKE (developed in the USA) , and the two-dimensional models CE-QUAL and WASP (developed in the USA). The DYRESM model can simulate hydrodynamic behaviour only, whereas MINLAKE, CE-QUAL and WASP can simulate both hydrodynamic and water quality behaviour. This report covers the extensive study that conducted on the MINLAKE model. The study is justified in view of the potential of the MINLAKE model to evaluate different treatment options: of the four models selected, it is the only model that can simulate more than one algal class. Thus it is an ideal tool to assess the effect of a chosen treatment option on, for example, algal succession.
14
McNamara, Les. "The role of water quality modelling in decision-making." View thesis, 2007. http://handle.uws.edu.au:8081/1959.7/18899.
Full textAbstract:
Thesis (Ph.D) -- University of Western Sydney, 2007.A thesis submitted to the University of Western Sydney, College of Health and Science, School of Natural Sciences, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliography.
15
Davies, John W. "Modelling of stormwater quality in combined sewers." Thesis, University of Westminster, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303530.
Full text
16
Heng, Hannah Yik Siew. "Water quality and habitat modelling in the urban River Tame." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398888.
Full textAbstract:
Urban river research is scarce. This thesis improves aspects of water quality and physical habitat modelling for sustainable urban river environment management using the highly urbanised River Tame in the West Midlands, UK as study catchment. Specifically, it focuses on modelling at the catchment scale and during high flow discharges. The River Tame system response to rainfall precipitation is complex, with influences from the wastewater treatment acting concurrently with the intricate combined sewer system. The complexity of the system response results in disassociation of critical flows with critical water quality such as biological oxygen demand and ammonium, reinforcing the belief that a design event approach for wet weather flow water quality modelling is impractical. Modelling intermittent discharges on a catchment scale basis through utilisation of a simple water quality model as opposed to sophisticated commercial tools achieved an acceptable level of success. The same order of high flow load magnitudes as field observations was found. Modelling physical habitat availability using a catchment scale methodology, which eliminates the need for intensive field data collection was also demonstrated, suitable for use particularly when water quality and flow regimes are the overriding factors in urban river health. Here, habitat suitability observations from high-resolution simulations over short distances were found to replicate lower resolution simulations over longer distances where cross-sectional shape and channel slope of study reaches are similar. However, with the knowledge of inter-relationships between the flow, water quality and physical habitat remains limited, the development of an integrated management between these different fields is still immature.
17
Asadollah-Fardi, Gholamreza. "A mathematical and experimental study on the surface water quality in Tehran." Thesis, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312476.
Full text
18
Cox, Brian A. "Dynamic modelling of dissolved oxygen : a case-study for the River Thames." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250691.
Full text
19
Kashefipour, Seyed Mahmood. "Modelling flow, water quality and sediment transport processes in reverine basins." Thesis, Cardiff University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618341.
Full text
20
Din, Sajjad-Mustafa Nasir. "A geochemical survey and water quality modelling study of the Lake St. Clair water system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0008/MQ52536.pdf.
Full text
21
Wolkersdorfer, Christian. "Water management at abandoned flooded underground mines : fundamentals, tracer tests, modelling, water treatment /." Berlin [u.a.] : Springer, 2008. http://www.loc.gov/catdir/toc/fy0803/2007943146.html.
Full text
22
Bomminayuni, Sandeep Kumar. "Modelling tidal flow for assessment of hydro-kinetic energy and bathing water quality in coastal waters." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/70060/.
Full textAbstract:
In this study, a hydro-environmental numerical model is utilised to further demonstrate the applicability of computer models to predict tidal flow in coastal waters. In particular, high resolution model simulations are performed at two selected sites: the Ogeechee Estuary, USA to assess the hydro-kinetic energy potential near Rose Dhu Island, a small island in the estuary; and at Swansea Bay, UK to assess faecal coliform pollution levels in the bay. Model results from the Ogeechee Estuary simulations revealed that better representation of branching smaller creeks located inshore enhanced the magnitude of tidal currents by approximately 30% near Rose Dhu Island. Evaluation of spatial and temporal distribution of currents revealed that local hot-spots of hydro-kinetic energy exist within the estuary and a maximum annual power of 4.75MW is available from the tidal streams surrounding the island. Investigation of the sensitivity of model parameters related to intertidal storage and bottom friction showed that ebb tide dominance in the estuary is reduced by lowering wetland elevation and by increasing bottom friction in the channel. Increasing the marsh friction to represent the resistance offered by marsh vegetation decreased the influence of intertidal storage on tidal distortion as ebb-dominance is reduced. Model results from the Swansea Bay simulations showed that three distinct flow patterns exist in the bay including re-circulating eddy like patterns, due to the presence of a headland located towards to the south-west end of the bay. The model-predicted distribution of Faecal Indicator Organisms (FIO) helped identify major pollution sources that negatively influence the rating of the Swansea Bay bathing water site. Investigation of the spatial distribution of FIO concentrations at the Designated Sampling Point (DSP) revealed that that the samples collected at DSP for compliance monitoring would correctly represent the pollution levels in the surrounding areas, however, at locations further off-shore significant spatial variability by up to five times was observed. As expected, intermittent peaks in FIO concentrations were noticeable following rainfall events, however, a strong temporal variability within a day was also observed at the DSP with concentration values varying by up to ten times in magnitude.
23
Maier, H. R. "Use of artificial neural networks for modelling multivariate water quality times series /." Title page and contents only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phm217.pdf.
Full text
24
Jiang, Dongxiang. "The application of Kriging technique to mathematical modelling of estuarine water quality." Thesis, University of Newcastle Upon Tyne, 1989. http://hdl.handle.net/10443/530.
Full textAbstract:
It is essential that estuarine modelling and surveying are carried out simultaneously because not only does the latter provide data required by the former but also the former is verified with data from the latter. This study integrates both research subjects from the panoramic point of view, aiming at improving modelling accuracy and reliability and increasing survey efficiency. Partially stratified estuaries are the most difficult types of estuaries to be modelled, in particular, the velocity field in such an estuary. A review of two commonly used methods to determine the velocity field, i. e., theoretical method and empirical method, revealed their inadequacies in real applications. Thus, a new approach using Kriging technique was originated and was tested on a finite element model of water quality. The model was formulated using a Galerkinfinite element method and was programmed in Fortran. Comparison between the simulation results and the field measurements for a salinity intrusion showed a high simulation accuracy. It is believed that the model in combination with the new approach would be a useful tool for estuarine modelling. The generalized Kriging method ensured that the new approach would be appropriate in practice. It was also applied to the investigation of sampling stations in the partially mixed estuary of the River Tees. It is essential to know how many sampling stations should be used and how they should be positioned. Two procedures were designed for solving the survey problems. They were the procedure of overall variance and the procedure of re-estimation. These procedures were capable of quantifing the relative significance of each sampling station and detecting redundant sampling stations. The 1975 survey was investigated, and useful conclusions were obtained.
25
Angeles, Justin Victor V. (Justin Victor Velayo). "Water quality modelling for recreational use in the Kallang River Basin, Singapore." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90006.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 42-45).
Singapore's Active, Beautiful, and Clean Waters Programme (ABC) aims to provide functional use of its water bodies to the public. The Kallang River Basin, being part of the ABC Programme, will be used for recreational purposes such as dragon boating and other water sports. In order to provide safe recreational use for the public, the water quality of the Kallang River Basin needed to be determined and modeled. The water quality indicator chosen to be analyzed was Escherichia coli (E. coli) bacteria. A heuristic study was performed in order to determine the water quality and as well determine if water quality modeling was feasible for the Kallang River Basin. The study employed the United States Environmental Protection Agency WASP (Water Quality Analysis Simulation Program) model. Through WASP model simulations, it was found that certain parts of the Kallang River Basin were not suitable for recreational purposes and others parts were deemed suitable. E. coli concentrations predicted by the model were within the range of actual field data but diurnal variations were not captured by the model for lack of data with which to specify diurnally varying inputs. The WASP model created by this study suggests that water quality modeling for the Kallang River Basin is feasible but there are modifications that need to be made to accurately capture diurnal variations experienced by the Kallang River Basin. Future investigation into the diurnal variations would contribute to creating a more complete and accurate model for the Kallang River Basin.
by Justin Victor V. Angeles.
M. Eng.
26
Slaughter, Andrew Robert. "Modelling the relationship between flow and water quality in South African rivers." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1006196.
Full textAbstract:
The National Water Act (Act 36 of 1998) provides for an ecological Reserve as the quantity (flow) and quality of water needed to protect aquatic ecosystems. While there are methods available to quantify the ecological Reserve in terms of flow, methods of linking flow to water quality are lacking. Therefore, the research presented in this thesis investigated various modelling techniques to estimate the effect of flow on water quality. The aims of the research presented in this thesis were: Aim 1: Can the relationship between flow and water quality be accurately represented by simple statistical models? Aim 2: Can relatively simple models accurately represent the relationship between flow and water quality? Aim 3: Can the effect of diffuse sources be omitted from a water quality model and still obtain realistic simulations, and if so under what conditions? Aim 4: Can models that solely use historical monitoring data, accurately represent the relationships between flow and water quality? In Chapter 3, simple Q-C regressions of flow and water quality were investigated using Department of Water Affairs (DWA) historical monitoring data. It was found that while flow versus salinity regressions gave good regression fits in many cases, the Q-C regression approach is limited. A mechanistic/statistical model that attempted to estimate the point and diffuse signatures of nutrients in response to flow was developed in Chapter 4 using DWA historical monitoring data. The model was verified as accurate in certain case studies using observed point loading information. In Chapter 5, statistical models that link land cover information to diffuse nutrient signatures in response to flow using DWA historical data were developed. While the model estimations are uncertain due to a lack of data, they do provide an estimation of the diffuse signature within catchments where there is flow and land cover information available. Chapter 6 investigates the extension of an existing mass-balance salinity model to estimate the effect of saline irrigation return flow on in-stream salinity. The model gave accurate salinity estimates for a low order stream with little or no irrigation within its catchment, and for a permanently flowing river within a catchment used extensively for irrigation. Chapter 7 investigated a modelling method to estimate the reaction coefficients involved in nitrification using only DWA historical monitoring data. Here, the model used flow information to estimate the residence time of nutrients within the studied river reaches. While the model obtained good estimations of nitrification for the data it was applied to, very few DWA data sets were suitable for the model. Chapter 8 investigated the ability of the in-stream model QUAL2K to estimate nutrient concentrations downstream of point and diffuse inputs of nutrients. It was found that the QUAL2K model can give accurate results in cases where point sources dominate the total nutrient inputs into a river. However, the QUAL2K simulations are too uncertain in cases where there are large diffuse source inputs of nutrients as the load of the diffuse inputs is difficult to measure in the field. This research highlights the problem of data scarcity in terms of temporal resolution as well as the range of constituents measured within DWA historical monitoring data for water quality. This thesis in addition argues that the approach of applying a number of models is preferable to applying one model to investigate the research aims, as particular models would be suited to particular circumstances, and the development of new models allowed the research aims of this thesis to be explored more thoroughly. It is also argued that simpler models that simulate a few key processes that explain the variation in observed data, are more suitable for implementing Integrated Water Resource Management (IWRM) than large comprehensive water quality models. From this research, it is clear that simple statistical models are not adequate for modelling the relationship between flow and water quality, however, relatively simple mechanistic models that simulate a limited number of processes and water quality variables, can provide accurate representations of this relationship. Under conditions where diffuse sources are not a major factor within a catchment, models that omit diffuse sources can obtain realistic simulations of the relationship between flow and water quality. Most of the models investigated in this thesis demonstrate that accurate simulations of the relationships between flow and water quality can be obtained using solely historical monitoring data.
27
Sloan, William Taylor. "Up-scaling hydrological processes and the development of a large-scale river basin modelling system." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299643.
Full text
28
Pierong, Rasmus. "Modelling of algae based wastewater treatment : Implementation of the River Water Quality Model no. 1." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-226484.
Full textAbstract:
The conventional wastewater treatment of today was developed aiming to mitigate problems occurring in wastewater recipients such as oxygen depletion and eutrophication. The focus of wastewater management has however broadened and major concern is now focused on the sustainability of the wastewater treatment process itself. Algae based wastewater treatment is an alternative to conventional treatment. It has the potential to yield an acceptable effluent quality at a lower ecological cost. This Degree Project was conducted as part of MOBIT, a project at Mälardalen University. The MOBIT project was aimed at the development of an algae based wastewater treatment process in an activated sludge environment. The aim of this Degree Project was to propose a model describing the dynamics of such a system. The model was constructed in Simulink, based on the River Water Quality Model no. 1. The River Water Quality Model no. 1 was chosen as the basis for modelling because it included the state variables and processes necessary to describe the dynamics of bacteria, algae and pH. The River Water Quality Model no. 1 was, as the name suggests, developed to describe a river system. It was hence considered important to evaluate if the model was applicable to an activated sludge environment. A major obstacle was the fact that no algae based activated sludge system had been studied prior the start of the MOBIT project, the project was pioneering. The lack of system understanding and of measurement data aggravated the evaluation. However, the proposed model was compared to the Activated Sludge Model No. 1 which was known to describe an activated sludge system accurately. The model structure of the River Water Quality Model no. 1 was considered a good starting point for future modelling of the algae based activated sludge process. However, the model set-up proposed in this report does not describe the system sufficiently well. Better system understanding and measurement data is needed in order to develop and calibrate the model.Dagens konventionella avloppsvattenrening har utvecklats för att minimera utsläpp av näringsämnen och kolföreningar då sådana utsläpp medför övergödning och syrebrist i mottagande vatten. På senare tid har reningsprocessen i sig hamnat i fokus då den är såväl energi- som resurskrävande. Algbaserad avloppsvattenrening är ett alternativ som har potential att ge tillfredsställande rening med ett betydligt mindre ekologiskt fotavtryck. Det här examensarbetet var en del av MOBIT, ett projekt vid Mälardalens högskola. MOBIT syftade till att utvärdera algbaserad avloppsvattenrening i form av en aktivslamprocess. Syftet med examensarbetet var att ta fram en modell för det planerade systemet. Modellen byggdes i Simulink och den baserades på en befintlig modell, River Water Quality Model no. 1. Den befintliga modellen valdes för att den inkluderade alla önskvärda tillståndsvariabler och processer, bland annat de som krävs för att beskriva alg-, bakterie- och pH-dynamik. Som namnet antyder utvecklades River Water Quality Model no. 1 för att beskriva ett flodsystem. Det var därför angeläget att utvärdera huruvida modellen var tillämpbar i en aktivslammiljö. Utvärderingen försvårades av att det vid tiden för examensarbetets utförande ännu inte fanns någon existerande algbaserad aktivslamprocess. Kunskapen om systemet var därför begränsad och det fanns ingen mätdata att kalibrera eller evaluera mot. I brist på mätdata jämfördes den framtagna modellen med en annan modell som var utvecklad för att beskriva just avloppsvattenrening, Activated Sludge Model No. 1. Arbetet resulterade i slutsatsen att River Water Quality Model no. 1 utgör en bra grund för modellering av den algbaserade aktivslamprocessen. Men, den modellkonfiguration som tas fram i denna rapport beskriver inte systemet särskilt bra. Bättre systemförståelse samt tillförlitlig mätdata krävs för att omarbeta och kalibrera den föreslagna modellen.
MOBIT
29
Thoe, Wai. "Integrated river management of the East River field studies, hydrologic and water quality modelling /." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38997575.
Full text
30
Lin, Daorui. "Global Sensitivity of Water Quality Modeling in the Gulf of Finland." Thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180285.
Full textAbstract:
The Gulf of Finland is the most eutrophied water body in the Baltic Sea, which is mainly caused by nutrient loads produced by human activities in its surrounding cities. In order to solve this environmental problem, a computational model based on the understanding the relations between eutrophication, water quality and sediments is needed to forecast the water quality variance in response to the natural and anthropogenic influences. A precise water quality model can be useful to assist the policy making in the Gulf of Finland, and even for the whole Baltic Sea. Kiirikki model, as one of these models describing the water quality of Baltic Sea in response of water quality variance, is a sediment and ecosystem based model, treating different sub-basins and layers as boxes. This study aims to assess the parameters’ sensitivity level on the scale of the Gulf of Finland. Firstly, the Morris sampling strategy is applied to generate economic OAT (One factor At a Time) samples before screening 50 out of 100 trajectories with distance as large as possible. In order to assess their sensitivity, index and indicator are needed. EE (elementary effect) is adopted to be the assessment index and four core eutrophication indicators from HELCOM 2009a are to be analyzed. By comparing the (σ,μ) and (σ,μ*) plots of each parameters’ EE values (σ is standard deviation, μ is mean value and μ* is the absolute mean value), some parameters are identified as potential sensitive parameter, such as the minimum biomass of cyanobacteria (Cmin), critical point of CO2 flux (CCr), the optimal temperature for detritus phosphorous mineralization (Toptgamma), maximum loss rate of algae (RAmax), optimal temperature for the growth of other algae (ToptmuA), Coefficient for temperature limiting factor for the growth of cyanobacteria (aTmuC), half-saturation coefficient of radiation for cyanobacteria (KIC) and so on. In contrast, the other parameters are ruled out as having very low values in terms of σ, μ and μ*. This is because the feature of Morris sampling strategy makes it easier to achieve high variance of the outputs, resulting into generally higher σ. Therefore, further investigation with different strategies is needed after the initial screening of the non-sensitive parameters in this study.
31
Hajigholizadeh, Mohammad. "Water Quality Modelling Using Multivariate Statistical Analysis and Remote Sensing in South Florida." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2992.
Full textAbstract:
The overall objective of this dissertation research is to understand the spatiotemporal dynamics of water quality parameters in different water bodies of South Florida. Two major approaches (multivariate statistical techniques and remote sensing) were used in this study. Multivariate statistical techniques include cluster analysis (CA), principal component analysis (PCA), factor analysis (FA), discriminant analysis (DA), absolute principal component score-multiple linear regression (APCS-MLR) and PMF receptor modeling techniques were used to assess the water quality and identify and quantify the potential pollution sources affecting the water quality of three major rivers of South Florida. For this purpose, a 15-year (2000–2014) data set of 12 water quality variables, and about 35,000 observations were used. Agglomerative hierarchical CA grouped 16 monitoring sites into three groups (low pollution, moderate pollution, and high pollution) based on their similarity of water quality characteristics. DA, as an important data reduction method, was used to assess the water pollution status and analysis of its spatiotemporal variation. PCA/FA identified potential pollution sources in wet and dry seasons, respectively, and the effective mechanisms, rules, and causes were explained. The APCS-MLR and PMF models apportioned their contributions to each water quality variable.
Also, the bio-physical parameters associated with the water quality of the two important water bodies of Lake Okeechobee and Florida Bay were investigated based on remotely sensed data. The principal objective of this part of the study is to monitor and assess the spatial and temporal changes of water quality using the application of integrated remote sensing, GIS data, and statistical techniques. The optical bands in the region from blue to near infrared and all the possible band ratios were used to explore the relation between the reflectance of a waterbody and observed data. The developed MLR models appeared to be promising for monitoring and predicting the spatiotemporal dynamics of optically active and inactive water quality characteristics in Lake Okeechobee and Florida Bay. It is believed that the results of this study could be very useful to local authorities for the control and management of pollution and better protection of water quality in the most important water bodies of South Florida.
32
Gombault, Colline. "Modelling water quality of the Pike River watershed under four climate change scenarios." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114486.
Full textAbstract:
The impacts of climate change on the hydrology and water quality of the Pike River watershed, an important contributor of nutrient loads to northern Lake Champlain, were predicted for the time horizon 2041-2070. Four water quality scenarios were simulated using a version of the Soil and Water Assessment Tool (SWAT) modified to suit Québec's agroclimatic conditions. Three of the scenarios were generated using climates simulated with the Fourth Canadian Regional Climate Model (CRCM4). The fourth scenario was generated using the climate simulated with the Arpege Regional Climate Model. SWAT was independently calibrated for the period 2001-2003, and then validated for the periods of 2004-2006 and 1980-2000, before inputting the climate scenarios. Potential mean changes predicted by these scenarios were then analysed for the evapotranspiration, surface and subsurface runoff, stream flow, sediment yields, and total phosphorus and nitrogen.After calibration, mean annual evapotranspiration, surface and subsurface flow as well as water percolation were found to correspond satisfactorily with the hydrology of the basin. Likewise, monthly predicted stream flow compared reasonably well with observed stream flow. The performance of SWAT in simulating sediment and nutrient yields was clearly improved after calibration but did not always reach standards of acceptability. As for climate change results, only one scenario predicted a significant increase in mean annual stream flow and nutrient loadings. However, when considering shorter time spans, simulations predicted significant changes including a winter stream flow two to three times greater than current stream flow and earlier spring floods. The identified causes are the early onset of spring snowmelt, a greater number of rainfall events and snowmelt episodes caused by higher winter and spring temperatures. In contrast, peak flows in April, as well as summer stream flow, appear to decrease but not always significantly. Nutrient delivery to the lake significantly increased in winter and occurred earlier in the year as a consequence of hydrological changes. A three- to four-fold increase in subsurface flow was also observed in winter which may increase nutrient losses through this pathway.L'impact des changements climatiques sur l'hydrologie et la qualité de l'eau du bassin versant de la rivière Aux Brochets, un tributaire contribuant substantiellement à l'apport de nutriments au Nord du lac Champlain, a été prédit pour l'horizon 2041-2070. Quatre scénarios de qualité de l'eau ont été simulés avec une version du Soil And Water Assesment Tool (SWAT) adaptée aux conditions agro-climatiques du Québec. Trois de ces scénarios ont été produits en utilisant des climats simulés avec la quatrième version du Modèle Régional Canadien du Climat (MRCC4). Le quatrième scénario a été produit en utilisant un climat simulé par le modèle régional de climat Arpège. SWAT a d'abord été calibré pour la période 2001-2003, puis validé sur les périodes 2004-2006 et 1980-2000 avant d'y intégrer les scénarios climatiques. Ensuite, les changements moyens potentiels causés par ces scénarios ont été analysés pour l'évapotranspiration, le ruissellement, les écoulements souterrains, le débit et la charge en sédiments et nutriments (phosphore et nitrogène total).Après calage, les valeurs annuelles et moyennes prédites d'évapotranspiration, de ruissellement de surface, d'écoulement souterrain ainsi que de percolation correspondaient à l'hydrologie du bassin. De même, les débits prédits mensuellement correspondaient aux débits mesurés. Le calage du modèle améliore clairement la capacité de SWAT à simuler les charges de sédiments et de nutriments. Cependant SWAT n'atteint pas systématiquement les standards de performance. En ce qui a trait aux changements climatiques, un seul scenario a prédit une hausse significative des débits et des charges annuelles en nutriments. Cependant, sur des périodes de plus courte durée des changements significatifs tels que des débits hivernaux deux à trois fois plus élevés que les débits actuels ont été simulés. De plus les crues printanières démarrent plus tôt dans la saison. Ces faits sont causés par la hausse des températures hivernales et printanières qui déclenche de nombreux épisodes de fonte de neige ainsi que de nombreux épisodes de pluie. À l'opposé, le pic des crues printanières en avril ainsi que les débits estivaux semblent diminuer, mais pas toujours significativement. Sous l'effet des changements hydrologiques prédits, l'apport des nutriments au lac augmente significativement en hiver et se fait plus tôt dans l'année. Il a aussi été observé que le volume des écoulements souterrains triplait voire quadruplait en hiver ce qui pourrait augmenter la proportion des nutriments qui est perdue via la voie souterraine.
33
Thornton, Gareth Jason Paul. "Controls on the water chemistry of headwater streams : synthesis and regional modelling." Thesis, Open University, 2000. http://oro.open.ac.uk/58086/.
Full textAbstract:
An understanding of the dominant processes controlling streamwater chemistry is critical for the development of a regional water quality model. The relative importance of a variety of catchment characteristics in determining streamwater chemistry in the English Lake District is investigated in this thesis. Fifty-five streams were sampled on a bimonthly basis over the period May 1996 through March 1997. Rock samples were analysed using X-ray fluorescence analysis. The major- and trace element geochemical data was used to classify the suite into six rock types. The geochemical data was also used to establish weathering patterns, which suggested that greywackes and lithic arenites weather the easiest, andesites and dacites exhibit heterogeneous weathering and the metamorphosed slate and granite are the most resistant to weathering. Forty-one (75%) of the streams can be considered sensitive to acidification on the basis of their alkalinity and thirty-eight (69%) can be considered sensitive to acidification on the basis of their calcium concentrations. Statistical analyses showed that flow-weighted concentrations of alkalinity and base cations were lowest in the catchments with resistant bedrock, thin or peaty soils, at high altitudes or receiving relatively high loads of sulphur and nitrogen deposition. A multiple regression model incorporating some of these factors provided a fairly good approximation of alkalinity concentrations on a spatial (R2 value of 56%) and temporal scale (R2 value of 49%). The predicted alkalinity was within 50 Ileq rl of the observed (simulated) values for 77% of the sites. Although the model has a fairly good predictive capability, its spatial and temporal applicability outside the study area is an unknown quantity. To satisfy the needs of policy makers and the hydrological community, the model needs to predict alkalinity with a high degree of accuracy in a variety of study areas. This has not been tested as yet, however, the variables used in the final model are not unique to the Lake District or the 1990's and therefore the model may prove to be an extremely useful tool indeed.
34
Ray, Shamik Kumar. "Water modelling studies to predict steel quality in a 4 strand delta-shaped tundish." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99013.
Full textAbstract:
Physical and mathematical modelling of fluid flow phenomena play an important role in studies of steel quality associated with the various steps in steelmaking and steel processing operations.In the continuous casting process, the tundish not only serves as an intermediate buffer, but with increasing demands for high quality steel, it has also evolved into a useful reactor for liquid steel refining. It is now a proven fact that a modern tundish is designed to carry out different metallurgical operations such as inclusion separation and floatation, alloy trimming, superheat control, calcium doped inclusion modification, thermal and particulate homogenization.
To carry out those operations effectively, certain parameters like Residence Time Distribution (RTD), Residual Ratio of Inclusions (RRI), Slag Entrainment and Vortex formation phenomena are generally studied and optimized using various tundish designs, and flow modification devices. These are usually specific to a given plant practice and to a targeted grade of steel.
A full scale physical model of a delta shaped, four strand tundish using water as the simulating fluid for liquid steel was used to study the fluid flow behavior of a 12 t tundish producing aluminium-killed steel billets., The above mentioned parameters were studied to predict the performance of the tundish using two different types of flow modification systems.
35
Jiang, Sanyuan [Verfasser], and Günter [Akademischer Betreuer] Meon. "Hydrological water quality modelling of nested meso scale catchments / Sanyuan Jiang ; Betreuer: Günter Meon." Braunschweig : Technische Universität Braunschweig, 2014. http://d-nb.info/1175821268/34.
Full text
36
Thoe, Wai, and 陶煒. "Integrated river management of the East River: field studies, hydrologic and water quality modelling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38997575.
Full text
37
Dube, Renias Admore. "Appropriate positioning of modelling as a decision support tool for surface water resources planning in South Africa." Thesis, Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08242006-122230.
Full textAbstract:
Thesis (Ph.D) (Microbiology and Plant Pathology)--University of Pretoria, 2006.Summaries in Afrikaans and English. Includes bibliographical references. Available on the Internet via the World Wide Web.
38
Lindenschmidt, Karl-Erich. "River water quality modelling for river basin and water resources management with a focus on the Saale River, Germany." [Potsdam] : [Bibliothek des Wissenschaftsparks Albert Einstein], 2006. http://deposit.d-nb.de/cgi-bin/dokserv?idn=981609600.
Full text
39
Botfield, Andrew Civil & Environmental Engineering Faculty of Engineering UNSW. "Kinetic modelling studies of As(III) oxidation in dark pH 3 and 8 Fenton - mediated and pH 8 Cu(II) - H2O2 systems." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2006. http://handle.unsw.edu.au/1959.4/31969.
Full textAbstract:
In this thesis, a combination of laboratory experimentation under well defined conditions coupled with a kinetic modelling approach is used to verify the existence and respective kinetic rates of previously unconfirmed or postulated mechanisms that drive and limit dark Fenton (Fe(II)/H2O2) - mediated As(III) oxidation at pH 3 and 8 and dark Cu(II) - H2O2 - mediated As(III) oxidation at pH 8. Dark Fenton - mediated oxidation of As(III) at pH 3 is first examined and the effects of the variation in the concentration of reactants (As(III), Fe(II) and H2O2), oxygen, phosphate and organics (2 - propanol, formate, and citrate) are reported and analysed. The kinetic models developed for these systems show high applicability to full scale water treatment application and key mechanistic findings include the significance of the cycling of Fe(II) / Fe(III) via HO2 ???/O2 ??????, the effects of As(IV) termination reactions in the absence of oxygen and the retarding effects of phosphate due to the postulated formation of a Fe(III) - phosphate complex (at a derived rate constant of 2.2 x 106 M-1s-1, that also appears to have negligible kinetic activity in terms of reduction to Fe(II) by HO2 ???/O2 ??????). The work also demonstrates the significance of the free radical by products of formate and citrate oxidation by ???OH (HCOO???/CO2 ?????? and 3HGA???2???). The examination of the dark Cu(II) - H2O2 - mediated oxidation of As(III) at pH 8 with variation in the concentration of reactants (As(III), Fe(II) and H2O2), carbonate and organics (2 - propanol, formate and citrate) demonstrated for the first time the high applicability of this system to the pre - oxidation of As(III) in water treatment and mechanistically that ???OH and CO3 ?????? are the dominant As(III) oxidants in this system. The As(III) oxidant CO3 ??????, is suggested to be generated by the interaction of ???OH and O2 ?????? with the carbonate matrix, at the respective rate constants of 4.9 x 107 M-1s-1 and 5.5 x 106 M-1s-1. Examination of the dark Fenton - mediated oxidation of As(III) at pH 8 and the effects of variation in the concentration of reactants (As(III), Fe(II) and H2O2), carbonate, organics (2 - propanol, formate and citrate) and Cu(II) demonstrates the varied potential mechanistic pathways in relation to the generation of As(III) oxidants from the Fenton reaction, Fe(II) + H2O2 such as Fe(IV) and CO3 ?????? and the previously dismissed ???OH, due to the presence of Fe(II) - citrate complexes. This work also demonstrates and models the enhancement of As(III) oxidation in the presence of an additional transitional metal ion, Cu(II).
40
Graham, Philip Mark. "Modelling the water quality in dams within the Umgeni Water operational area with emphasis on algal relations / Philip Mark Graham." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1022.
Full textAbstract:
Based on many years of water quality (including algal) and water treatment cost data,
available at Umgeni Water, a study was undertaken to better understand the water
quality relationships in man made lakes within the company's operational area, and
to investigate how water quality affected the cost of treating water from these lakes.
The broad aims to the study were to:
identify the key environmental variables that were affecting algal populations
in lakes; and if these were significant to
establish predictive models relating algae to the water quality; and to
develop models relating the water quality in lakes to the cost of treating water
from the lakes.
Semi-quantitative models were developed relating algal abundances with important
environmental variables. In most cases, the models developed were related to algal
populations that were known to adversely affect water treatment. Direct algal impact
on water treatment processes was through the production of either taste and odour
forming compounds (requiring advanced water treatment, such as use of activated
carbon), or their ability to clog sand filters and so reduce filter run times (requiring
more frequent backwashing of filters).
Thereafter lake water quality parameters (which included water physico-chemistry
and algae) were investigated to determine which factors were most significantly
impacting on water treatment and hence treatment costs at selected water works
(WW) within the Umgeni Water operational area. Models were developed relating
raw water quality entering respective water works with costs incurred in treating that
water. The models allowed simulations to be developed illustrating how changes in
water quality might impact on water treatment costs. The impact of eutrophication
and contamination of rivers and lakes, and its subsequent impact on surface water
resources, was quantified.Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2004.
41
Koçyigit, Önder. "Modelling of water quality and sediment transport in aquatic basins using an unstructered grid system." Thesis, Cardiff University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404867.
Full text
42
Kamish, Wageed. "Hydrosalinity modelling of the Berg River using ACRUSalinity." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2067.
Full textAbstract:
Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008.In recent years, concern about the water quality in the Berg River received a fair degree of attention, particularly with the imminent construction of the Berg Water Project (BWP). Particular concerns have been expressed about the water quality with respect to total dissolved salts (TDS) at Misverstand Dam. In previous studies (Fourie and Görgens, 1977) it was identified that the saline water was mostly generated in the lower portion of the Berg River Catchment (Matjies, Moorreesburg and Sandspruit Rivers) and that the abstraction of acceptable quality water higher up in the Berg River could possibly result in salinity problems at Misverstand Dam. Contrary to expectation, these studies also showed that for the most saline catchments, a winter peak in TDS concentrations also existed. To help address these concerns, a Water Research Commission (WRC) project was initiated in 2003 in which the newly-developed salinity module of the daily Agricultural Catchment Research Unit (ACRU) agrohydrological model, known as ACRUSalinity, would be configured for the Berg River Catchment. This model had previously been configured and calibrated for the Mkhomazi Catchment (Teweldebrhan, 2003) which exhibited relatively low streamflow TDS concentrations (100 mg/l) and it was deemed necessary to ascertain whether comparable TDS values could be simulated in the Berg River Catchment, where TDS concentration could rise to well above 1 000 mg/l in certain tributaries. In this project, ACRUSalinity was configured for the Berg River Catchment on a distributed basis, aiming to capture the spatial distribution of rainfall and geophysical characteristics which inherently exist in a catchment as expansive as the Berg. Initial application of the "Beta version" of ACRUSalinity to the Berg River Catchment revealed that it failed to produce simulated TDS values which were representative of the observed data. It became evident that the model required both additional salinity-related functions and modifications of existing functions. After the implementation of these algorithm changes the correspondence of simulated and observed TDS concentrations improved markedly. Verification of the ACRUSalinity simulated flows and calibration of the salinity-related parameters was based on the values of predefined objective functions. Reasonably representative flows could be obtained provided that the catchment discretisation and driver rainfall selection process were adequate. Salinity related parameters were determined purely on an iterative basis, although a priori estimation of these parameters was possible. Preliminary interdependency tests of these parameters revealed that the final calibrated set of salinity-related parameters was probably not unique and that some a priori decision making would be required when selecting the most realistic set of parameters. Quantification of the potential effect of the Berg River Dam on the TDS concentrations at Misverstand Dam was achieved as follows: the ACRUSalinity model was verified for flow and calibrated for TDS at available and reliable flow gauging stations. This was then followed by a long-term simulation run which yielded daily TDS time series for comparison, on an exceedance basis, with the observed record. Since the concern about the possible deterioration of water quality at Misverstand Dam was only a winter concern (May to September), comparisons were only drawn over this period. The flow-routing option in ACRUSalinity was not activated and a 1:1 daily comparison of flows and TDS concentrations, based on values of the objective function, was thus not possible. Results from this study showed that even with a daily model, the exceedance percentages of the TDS concentrations after the construction of the Berg River Dam were comparable with the exceedance percentages obtained from the original monthly modelling study (DWAF, 1993). In this study, however, it was possible to capture the increasing TDS concentration which was evident over winter months in the observed data record for the Matjies River and Sandspruit River catchments. The testing of the model’s effectiveness in the evaluation of engineering options was accomplished as follows: several options for ameliorating the possible deterioration of water quality at Misverstand Dam were defined, based on its practicality and cost of implementation. For example, the Withoogte water treatment works abstracts water from Misverstand Dam for supply to the West Coast region when water quality is acceptable (i.e. a TDS lower than 450 mg/l). It was proposed that to minimise the effect of periods when no abstraction from Misverstand could occur due to unacceptable water quality, a second reservoir at the treatment works should be lined and used to provide bridging storage for water from Misverstand Dam when the water quality was acceptable. The calibrated ACRUSalinity model was then modified to reflect the physical attributes of this engineering scenario of interest to produce sets of flow and TDS time series which could be further analysed to determine assurance of supply, in terms of predetermined TDS concentration thresholds in Misverstand Dam. Using this particular engineering option, the analysis revealed that a 300 mg/l TDS upper-limit at Misverstand was too stringent and that 450 mg/l was probably more realistic.
43
Chingombe, Wisemen. "Effects of land-cover - land-use on water quality within the Kuils - Eerste River catchment." Thesis, University of Western Cape, 2012. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5893_1373463134.
Full textAbstract:
The most significant human impacts on the hydrological system are due to land-use change. The conversion of land to agricultural, mining, industrial, or residential uses significantly alters the hydrological characteristics of the land surface and modifies pathways and rates of water flow. If this occurs over large or critical areas of a catchment, it can have significant short and long-term impacts, on the quality of water. While there are methods available to quantify the pollutants in surface water, methods of linking non-point source pollution to water quality at catchment scale are lacking. Therefore, the research presented in this thesis investigated modelling techniques to estimate the effect of land-cover type on water quality. The main goal of the study was to contribute towards improving the understanding of how different land-covers in an urbanizing catchment affect surface water quality. The aim of the research presented in this thesis was to explain how the quality of surface runoff varies on different land-cover types and to provide guidelines for minimizing water pollution that may be occurring in the Kuils-Eerste River catchment. The research objectives were
(1) to establish types and spatial distribution of land-cover types within the Kuils-Eerste River catchment, (2) to establish water quality characteristics of surface runoff from specific land-cover types at the experimental plot level, (3) to establish the contribution of each land-cover type to pollutant loads at the catchment scale. Land-cover characteristics and water quality were investigated using GIS and Remote Sensing tools. The application of these tools resulted in the development of a land-cover map with 36 land classifications covering the whole catchment. Land-cover in the catchment is predominantly agricultural with vineyards and grassland covering the northern section of the catchment. Vineyards occupy over 35% of the total area followed by fynbos (indigenous vegetation) (12.5 %), open hard rock area (5.8 %), riparian forest (5.2 %), mountain forest
(5 %), dense scrub (4.4 %), and improved grassland (3.6 %). The residential area covers about 14 %. Roads cover 3.4 % of the total area. Surface runoff is responsible for the transportation of large quantities of pollutants that affect the quality of water in the Kuils-Eerste River catchment. The different land-cover types and the distribution and concentration levels of the pollutants are not uniform. Experimental work was conducted at plot scale to understand whether land-cover types differed in their contributions to the concentration of water quality attributes emerging from them. Four plots each with a length of 10 m to 12 m and 5 m width were set up. Plot I was set up on open grassland, Plot II represented the vineyards, Plot III covered the mountain forests, and Plot IV represented the fynbos land-cover. Soil samples analyzed from the experimental plots fell in the category of sandy soil (Sa) with the top layer of Plot IV (fynbos) having loamy sand (LmSa). The soil particle sizes range between fine sand (59.1 % and 78.9 %) to coarse sand (between 7 % and 22 %). The content of clay and silt was between 0.2 % and 2.4 %. Medium sand was between 10.7 % and 17.6 %. In terms of vertical distribution of the particle sizes, a general decrease with respect to the size of particles was noted from the top layer (15 cm) to the bottom layer (30 cm) for all categories of the particle sizes. There was variation in particle size with depth and location within the experimental plots.Two primary methods of collecting water samples were used
grab sampling and composite sampling. The quality of water as represented by the samples collected during storm events during the rainfall season of 2006 and 2007 was
used to establish
water quality characteristics for the different land-cover types. The concentration of total average suspended solids was highest in the following land-cover types, cemeteries (5.06 mg L-1), arterial roads/main roads (3.94 mg L-1), low density residential informal squatter camps (3.21 mg L-1) and medium density residential informal townships (3.21 mg L-1). Chloride concentrations were high on the following land-cover types, recreation grass/ golf course (2.61 mg L-1), open area/barren land (1.59 mg L-1), and improved grassland/vegetation crop (1.57 mg L-1). The event mean concentration (EMC) values for NO3-N were high on commercial mercantile (6 mg L-1) and water channel (5 mg L-1). The total phosphorus concentration mean values recorded high values on improved grassland/vegetation crop (3.78 mg L-1), medium density residential informal townships (3mgL-1) and low density residential informal squatter camps (3 mg L-1). Surface runoff may also contribute soil particles into rivers during rainfall events, particularly from areas of disturbed soil, for example areas where market gardening is taking place. The study found that different land cover types contributed differently to nonpoint source pollution. A GIS model was used to estimate the diffuse pollution of five pollutants (chloride, phosphorus, TSS, nitrogen and NO3-N) in response to land cover variation using water quality data. The GIS model linked land cover information to diffuse nutrient signatures in response to surface runoff using the Curve Number method and EMC data were developed. Two models (RINSPE and N-SPECT) were used to estimate nonpoint source pollution using various GIS databases. The outputs from the GIS-based model were compared with recommended water quality standards. It was found that the RINSPE model gave accurate results in cases where NPS pollution dominate the total pollutant inputs over a given land cover type. However, the N-SPECT model simulations were too uncertain in cases where there were large numbers of land cover types with diverse NPS pollution load. All land-cover types with concentration values above the recommended national water quality standard were considered as areas that needed measures to mitigate the adverse effects of nonpoint pollution. The expansion of urban areas and agricultural land has a direct effect on land cover types within the catchment. The land cover changes have adverse effect which has a potential to contribute to pollution.
44
Varanka, S. (Sanna). "Multiscale influence of environmental factors on water quality in boreal rivers:application of spatial-based statistical modelling." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526210735.
Full textAbstract:
Abstract Rivers create unique habitat for aquatic life and provide ecosystem services for humans. Thus, degradation of river water quality is a serious, global problem. Water quality is the outcome of anthropogenic and natural landscape factors and the interaction of these two. To improve water quality, robust and quick methods are needed to study the complex, spatio-temporally dependent relation between water quality and environment conditions across extensive areas. This thesis aimed to study the relationship between water quality (total phosphorus and nitrogen, pH, water colour and dissolved oxygen) and environmental factors in boreal rivers combining grid-based data and statistical methods. The study comprised of 34 Finnish rivers with their catchments. First, the effect of natural and human-induced environmental factors on water quality was studied. Then, (a) the ability of the characteristics of different spatial scales around the river channel and under different discharge conditions to predict water quality was explored and (b) the suitability of the applied statistical methods (generalized linear and additive models, partitioning methods, non-metric multidimensional scaling) in water quality studies was evaluated. As expected, the results highlighted the impact of agricultural activities on water quality as nutrients and pH increased, together with the cover of agricultural activities. However, when studied as a group, natural factors explained water quality better than land use/cover. Lakes were strongly related to decreased nutrients and water colour. The effect of fine-grained soils on nutrients and pH was positive. In the scale studies, nutrients and water colour were best explained by the characteristics of the entire catchment but pH was mostly predicted by the characteristics of the 50 m riparian zone. The connection between water quality and environment was strongest during high-flow discharge periods. The results encourage the use of the applied methods, showing that the combination of grid-based data and advanced statistical methods provide an efficient first-filter estimate of water quality-environment relations. Spatial-based statistical modelling provides a crucial framework for river, water resources and land use management. The applied methods can also be seen as essential tools when predicting the impacts of global change on water qualityTiivistelmä Joet luovat vesielämälle ainutlaatuisen elinympäristön ja tarjoavat ihmisille ekosysteemipalveluja. Jokien vedenlaadun huononeminen onkin vakava, maailmanlaajuinen uhka. Vedenlaatua määrittävät luonnolliset ja ihmisen muokkaamat ympäristötekijät sekä näiden yhteisvaikutus. Vedenlaadun kohentamiseksi tarvitaan luotettavia ja nopeita menetelmiä, joiden avulla voidaan tutkia monimutkaista, alueellisesti ja ajallisesti riippuvaa yhteyttä vedenlaadun ja ympäristöolojen välillä laajoilla alueilla. Tässä väitöskirjassa oli tavoitteena tutkia vedenlaadun (kokonaisfosfori ja -typpi, pH, väriluku ja liukoinen happi) ja ympäristön yhteyttä boreaalisella vyöhykkeellä käyttäen paikkatietoaineistoja ja tilastollisia menetelmiä. Tutkimusalueena oli 34 suomalaista jokea valuma-alueineen. Ensinnäkin tutkittiin luonnollisten ympäristötekijöiden ja ihmistoiminnan vaikutusta vedenlaatuun. Tavoitteena oli myös selvittää, miten joen ympärillä olevien erikokoisten vyöhykkeiden ominaisuudet ja vaihtelevat virtaamaolosuhteet selittävät vedenlaatua. Lopuksi arvioitiin käytettyjen tilastollisten menetelmien (yleistetyt lineaariset ja additiiviset mallit, hajonnan ositusmenetelmät, ordinaatioanalyysi) soveltuvuutta vedenlaatututkimuksissa. Tuloksissa korostui odotetusti valuma-alueen maatalouden vaikutus vedenlaatuun. Ravinteiden määrä ja pH-luku kasvoivat maatalouden lisääntyessä. Muuttujien ryhmittäisessä tarkastelussa ympäristön luonnolliset ominaisuudet selittivät vedenlaatua maankäyttöä/-peittoa paremmin. Järvisyyden lisääntyminen oli yhteydessä ravinteisuuden ja väriluvun laskuun. Hienorakeiset maalajit olivat yhteydessä ravinteisuuden ja pH-luvun nousuun. Mittakaavatarkastelussa ravinteisuutta ja värilukua ennustivat parhaiten koko valuma-alueen ominaisuudet, mutta pH-lukua selittivät parhaiten ominaisuudet 50 m:n vyöhykkeellä joen ympärillä. Ympäristön ja vedenlaadun yhteys oli voimakkaimmillaan, kun jokien virtaamat olivat korkeimmillaan. Tämä väitöskirja osoittaa, että paikkatietoaineistojen ja sovellettujen tilastollisten menetelmien yhteiskäyttö tuottaa tehokkaita malleja vedenlaadun ja ympäristön välisestä yhteydestä. Spatiaalis-tilastollinen mallinnus tarjoaa tärkeän viitekehityksen jokien ja vesistöjen käytön sekä maankäytön suunnitteluun. Lähestymistapa voidaan nähdä myös tärkeänä välineenä ennustettaessa globaalimuutoksen vaikutusta vedenlaatuun
45
Nanayakkara, Mummullage Sandya Wasanthi. "Source characterisation of urban road surface pollutants for enhanced water quality predictions." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82065/1/Sandya%20Wasanthi_Nanayakkara%20Mummullage_Thesis.pdf.
Full textAbstract:
This study developed a comprehensive research methodology for identification and quantification of sources responsible for pollutant build-up and wash-off from urban road surfaces. The study identified soil and asphalt wear, and non-combusted diesel fuel as the most influential sources for metal and hydrocarbon pollution respectively. The study also developed mathematical models to relate contributions from identified sources to underlying site specific factors such as land use and traffic. Developed mathematical model will play a key role in urban planning practices, enabling the implementation of effective water pollution control strategies.
46
Long, Stephanie. "Simulating Everglades National Park hydrology and phosphorus transport under existing and future scenarios using numerical modeling." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1543.
Full textAbstract:
The Florida Everglades has a long history of anthropogenic changes which have impacted the quantity and quality of water entering the system. Since the construction of Tamiami Trail in the 1920's, overland flow to the Florida Everglades has decreased significantly, impacting ecosystems from the wetlands to the estuary. The MIKE Marsh Model of Everglades National Park (M3ENP) is a numerical model, which simulates Everglades National Park (ENP) hydrology using MIKE SHE/MIKE 11software. This model has been developed to determine the parameters that effect Everglades hydrology and understand the impact of specific flow changes on the hydrology of the system.
As part of the effort to return flows to the historical levels, several changes to the existing water management infrastructure have been implemented or are in the design phase. Bridge construction scenarios were programed into the M3ENP model to review the effect of these structural changes and evaluate the potential impacts on water levels and hydroperiods in the receiving Northeast Shark Slough ecosystem. These scenarios have shown critical water level increases in an area which has been in decline due to low water levels. Results from this work may help guide future decisions for restoration designs.
Excess phosphorus entering Everglades National Park in South Florida may promote the growth of more phosphorus-opportunistic species and alter the food chain from the bottom up. Two phosphorus transport methods were developed into the M3ENP hydrodynamic model to determine the factors affecting phosphorus transport and the impact of bridge construction on water quality. Results showed that while phosphorus concentrations in surface waters decreased overall, some areas within ENP interior may experience an increase in phosphorus loading which the addition of bridges to Tamiami Trail. Finally, phosphorus data and modeled water level data was used to evaluate the spectral response of Everglades vegetation to increasing phosphorus availability using Landsat imagery.
47
Lindenschmidt, Karl-Erich [Verfasser]. "River water quality modelling for river basin and water resources management with a focus on the Saale River, Germany / Karl-Erich Lindenschmidt." [Potsdam] : [Bibliothek des Wissenschaftsparks Albert Einstein], 2006. http://d-nb.info/981609600/34.
Full text
48
McGrane, Scott James. "The hydrology of mesoscale catchments in Scotland : hydroclimatic trends, monitoring and modelling isotope dynamics and water quality implications." Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=195978.
Full textAbstract:
Understanding the spatial and temporal dynamics of catchment systems is crucial to understanding how hydrological behaviour may change over time and how this impacts on crucial aspects of catchment management such as flood generation, water resource management and the sources and fluxes of sediment, nutrients and contaminants. A combined statistical analysis was undertaken to assess whether similar catchment groupings respond to changing climatic drivers in the same way. A k-means cluster and PCA analysis grouped catchments in four clusters, which were differentiated by their topographical differences between lowland and upland catchments. Lowland catchments exhibited similar behaviours to changing trends of key hydroclimatic variables whereas more upland catchments showed diverse responses. We assessed the behaviour of 8 mesoscale catchments with increasing lowland areas for spatial and temporal runoff dynamics via the application of environmental tracers (stable isotopes and Gran alkalinity). Mean transit times were estimated using a lumped convolution integral model and lowland catchments with greater coverage of sedimentary bedrock exhibited longer turnover for water and solute fluxes. Tracer data was then implemented into a conceptual rainfall-runoff model to develop a model, which could represent both spatial and temporal dynamics rather than simply recreating the observed stream hydrograph. Finally, we assessed the role of dominant landscape characteristics (urban environments and grazing pastures) on the sources and fluxes of microbial contaminant risk to water quality. Catchments which had larger urban coverage and higher portion of grazing pastures yielded higher concentration fluxes of faecal coliforms which provided a first-order approximation of water quality risk at the catchment scale.
49
Lefebvre, Karine. "Diagnostic et quantification des flux nappe - rivière : modélisations hydrodynamique et géochimique du bassin versant de l'Yvette amont (France)." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS152/document.
Full textAbstract:
Dans le contexte péri-urbain à dominance agricole de l’Ile de France, les pressions anthropiques exercées sur les rivières jouent autant sur la qualité que sur le débit des cours d'eau. Située au sud-ouest de Paris, l’Yvette draine un bassin versant de 202 km²et à la géologie homogène. Elle est alimentée directement par des stations d'épuration (STEP) et par la nappe des sables de Fontainebleau qui représente la principale source d’eau. Sur ce type de bassin, la gestion durable du système riverain repose sur la connaissance de la distribution des flux nappe – rivière et sur l’impact de cette répartition sur la qualité des cours d’eau.La dynamique des flux d’eau a été suivie grâce à l’implantation de stations hydrométriques aux points clés du réseau hydrographique (i.e. exutoires des principaux affluents, aval des confluences sur l’Yvette). Les flux chimiques ont été étudiés par analyses d’échantillons d’eau recueillis lors de campagnes de terrain effectuées en période d’étiage sur les cours d’eau. Un modèle conceptuel global, calibré à partir des chroniques de débit, a permis (i) d’estimer des variations spatiales de la recharge de la nappe (60 – 160 mm.an-1), et (ii) d’établir une répartition journalière des parts d’eau de nappe, de STEP et de ruissellement en rivière, pour la période 2001-2014. Par ailleurs, l’analyse des traceurs géochimiques (e.g. Cl-, NO3-, SO42-) et isotopiques (222Rn, δ18Oeau, δ2Heau) soutient la prédominance, aussi bien quantitative que qualitative, de la nappe sur les rivières.D’un point de vue hydrodynamique, le contexte géomorphologique homogène procure aux rivières une dynamique similaire avec des épisodes de crues très courts (de l’ordre de quelques heures) et des périodes d’étiages marqués, quelle que soit la saison. L’étude par sous-bassin a mis à jour une différence entre les bassins topographiques et les bassins d’écoulement souterrains, créant des déficits hydriques sur l’amont de certains cours d’eau (e.g. Mérantaise, Ru des Vaux) au profit d’autres (e.g. Rhodon). Le parallèle entre bassins topographique et souterrain n’a pu se faire qu’au niveau du cours principal de l’Yvette. Sur la période 2001-2014, le débit de l’Yvette provient en moyenne à 55 % de la nappe, à 38 % du ruissellement et à 8 % des STEP. En période de basses eaux, la contribution des STEP reste sensiblement identique tandis que la nappe constitue la principale alimentation des rivières (90 %), contrôlant donc leur qualité. Mais la composition chimique de ce soutien souterrain n’est pas homogène. Pour déterminer l’origine de ces disparités, un travail à plus petite échelle a été conduit sur un affluent majeur de l’Yvette (le Rhodon). La décharge de la nappe en rivière y est bimodale : 15 % arrive par voie souterraine et 85 % transite par les milieux humides en surface. Au sein des zones humides sont observées de fortes hétérogénéités dans les écoulements et leur chimie, avec des flux de subsurface totalement épurés en nitrates et du ruissellement riche en nutriments. La prédominance de des flux de surface réduit fortement le pouvoir épurateur des milieux humides, avec seulement 6 % des eaux de nappe épurées avant leur décharge en rivière. Cette faible efficacité renforce l’impact direct de la qualité de la nappe sur les rivières. Sur le bassin, la nappe est stratifiée par l’intervention de nombreux processus de recharge (infiltrations d’eau d’étang, de STEP, de zones humides de plateau). Les petits sous-bassins (< 50 km²) semblent dominés par cette stratification, ainsi que par les apports de STEP qui contribuent aux flux chimiques des rivières à hauteur de 30 à 50 %. Le cours principal de l’Yvette, dans sa partie aval, dépend des mélanges issus des confluences avec ses affluents. Les outils utilisés ici ont donc mis en avant les différences de fonctionnement des bassins selon l’échelle concernée, tout en reliant l’importance de la compréhension du système à petite échelle pour la gestion à grande échelleIn the peri-urban context with large farm practices of the Paris region, anthropogenic pressures on streams and rivers impact both their flow and quality. Located in the southwestern of Paris, the Yvette stream drains a watershed of 202 km², in a homogeneous geological context. The stream is sustained by waste water treatment plant (WWTP) and by the Fontainebleau sands aquifer which represents the main source of water.In this context, the sustainable management of the stream and its riparian zones needs the assessment of groundwater discharge locations and chemistry, and their impact on the stream water quality.Water fluxes in the stream and in its main tributaries have been recorded at 11 stations. Dissolved elements distributions have been studied by field works in low-flows conditions. A lumped model, calibrated with stream flow hydrographs, has allowed (i) the estimation of groundwater recharge rates (60 – 160 mm.y-1) and (ii) the distribution of stream flow contributions between 2001 and 2014 (i.e. 55 % from groundwater, 38 % from runoff and 8 % from WWTP). Moreover, the use of geochemical and isotopic tracers (e.g. Cl-, NO3-, SO42-, 222Rn, δ18Owater, δ2Hwater) confirmed the large impact of groundwater on stream flow and quality.The hydrological dynamics of the Yvette stream and its tributaries are similar because of the homogeneity of the geomorphological context of the catchment. The flood events are really fast (on the order of hours) and low-flow conditions can be observed in every season. The discretization of the Yvette catchment in 11 sub-watersheds highlighted a divergence between the topographical and hydrogeological catchments. This generates a water deficit in some tributaries heads (e.g. Mérantaise, Ru des Vaux) in favor of some others (e.g. Rhodon). The matching limits of these catchments can only be made on the Yvette channel. During the 2001 – 2014 period, considering a fairly constant WWTP contribution, the groundwater discharge provides more than 90 % of the stream flow during low-flow conditions. This highlights a stream quality dominated by groundwater discharge. However, groundwater chemistry largely varies over the catchment. To study this phenomenon, a small-scale field work has been directed on the Rhodon stream, a main tributary of the Yvette River. At this scale, the groundwater discharge appeared to have two main pathways: 15 % come from the streambed while 85 % transit in wetlands before going to the stream. Within these wetlands, a large part of groundwater flows at the surface and has high levels of nutrients, whereas a small part (6 %) goes through sediments and is nutrients free. reduces The purifying power of these wetlands, significantly reduced by this distribution, is likely related to historical drainage and reinforces the direct connection between the stream and groundwater quality. On the Yvette catchment, the stratification of groundwater chemistry is due to several recharge processes (e.g. pond water infiltration, WWTP effluents infiltration, wetlands water infiltration). Small sub-watersheds (< 50 km²) seem to be dominated by (i) this stratification, and (ii) the WWTP discharges which can contribute from 30 % to 50 % to dissolved fluxes in the streams. The main channel of the Yvette stream primarily depends of the mixing of its tributaries waters. The methods developed here allowed highlighting (i) differences of catchment functioning according to the scale used, and (ii) the utmost importance of the small-scale assessment to understand/decipher and manage streams at larger scales
50
Mahlathi, Christopher Dumisani. "In-Stream water quality modelling and optimisation by mixed-integer programming : simulation and application in actual system." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/40840.
Full textAbstract:
Water scarcity has become a global problem due to diminishing water resource and
pollution of the remaining resources. The problems arising fromwater scarcity are exacerbated
rapid urbanisation and industrialisation. Water quality management systems are introduced.
Numerous water management methods exist some of which, if applied e ectively, can
remedy these problems. In South Africa, water management systems are urgently needed
to start addressing issues around the longterm sustainability of our limited water resource.
Water quality modelling is one of the tools employed to assist in validating decisions
made during the planning phase of a water quality management system. It also provides
a means of exploring viable options to be considered when these decisions are to be made.
A range of management options exist and implementing all of them may prove costly,
therefore optimisation techniques are utilised to narrow down options to the most e ective
and least costly among the available choices. Commonly, water quality models are used to
predict concentrations in the river from which constraint equations are generated. The
constraint equations are used in optimisation models to generate feasible solutions by
either maximising or minimising the objective function. In this case the objective function
is wastewater treatment cost. Constraints equations are based on the set in-stream water
quality standard at selected theoretical measuring stations (checkpoints) in the stream
and a feasible solution is one that suggests a treatment method that will ensure water
quality standards are met at the lowest regional treatment cost.
This study focused on the Upper Olifants river catchment near Witbank in Mpumalanga
province. This catchment is subjected to extensive wastewater e uents from various
mining operations and wastewater treatment plants. The aim here was to develop a
water quality model for predicting dissolved oxygen (DO) concentration in the river, and
to use a modelling approach to generate constraint equations for the system.
A Streeter-Phelps stream simulation model was employed to predict DO concentration in
the river. A mixed-integer programming technique was then used to evaluate the impact
of nine wastewater treatment facilities discharging e uent into the river. Treatment levels
were varied to test model reliability. The coupled stream simulation and optimisation model produced feasible solutions under
2 minutes, with each solution suggesting a range of treatment levels which ensured that
the critical DO concentration was above 5 mg/L and the most stringent DO concentration
the system could manage without violations anywhere else in the stream was obtained to
be 7mg/L.Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Chemical Engineering
unrestricted