Development and population are rapidly increasing in urbanizing areas of North Texas and so is the need to understand changes in storm water runoff flow and its contamination by nutrients, sediment, pesticides and other toxicants. This study contributes to this understanding and has two primary components: first, development of a graphical user interface for a geographic information system and storm water management database, and second, performing a two-scale hydrological modeling approach (the US Corp of Engineers HEC-HMS model and the US Environmental Protection Agency SWMM model). Both primary components are used together as a toolkit to support the storm water management program of the City of Carrollton, located in North Texas. By focusing limited city resources, the toolkit helps storm water managers in the process of compliance with federal regulations, especially the National Pollution Discharge Elimination System permit, and provides guidance for reporting, planning and investigation. A planning example was conducted by modeling potential changes in storm water quality due to projections of land use based on the City of Carrollton's Comprehensive Plan. An additional component of this study is the evaluation of future changes in surface water quantity and quality in the North Central Texas area, specifically in a rural but rapidly urbanizing subbasin area of the greater Lake Lewisville watershed. This was accomplished using the US Corp of Engineers HEC-HMS hydrological model. Precipitation scenarios were derived from years of historically high, medium, and low annual precipitation. Development scenarios were derived from current land use in the Lake Lewisville sub basin, current land use in the city of Carrollton, and from Markov projections based on recent land use change calculated from satellite images of 1988 and 1999. This information is useful for future land use planning and management of water resources in North Texas.

La gestion des eaux urbaines de temps de pluie est devenue une priorité depuis quelques années, au regard des problématiques d'inondations et de pollutions des cours d'eau qui remettent en cause l'atteinte des objectifs de la DCE. En outre, les filtres plantés de roseaux sont reconnus comme des solutions fiables pour le traitement des eaux usées depuis plus de 20 ans. Par ailleurs, leur adaptation à d'autres types d'effluents a été mise en place récemment (traitement tertiaire, effluents dilués, lits de séchage de boues), et la gestion des eaux de temps de pluie s'inscrit dans le cadre de cette extension de fonction. Bien que ce système combine à la fois des capacités de stockage et de traitement, Uhl et Dittmer (2005) ont mis en avant des dysfonctionnements (mort des roseaux en période sèche, chutes de performances). Ces auteurs soulignent aussi la nécessité d'optimiser les règles et outils de dimensionnement.Le projet SEGTEUP vise donc, via un suivi sur pilotes de grande taille et une modélisation hydrodynamique, à fournir des règles de conception à intégrer dans un futur outil de conception simplifié, utilisable à l'échelle du territoire français. L'étude des pilotes vise donc à tester différents matériaux et conceptions, alors que la modélisation met en évidence les principaux paramètres d'influence de l'écoulement. Au final, la filtration apparaît comme le principal processus d'élimination de la pollution organique et des micropolluants, alors que l'adsorption de la matière organique dissoute est négligeable. Par ailleurs, l'emploi d'un matériau à forte capacité d'adsorption (zéolite) accroît considérablement les capacités de rétention de l'ammonium. L'utilisation de tels matériaux est particulièrement recommandée en cas de charges en ammonium particulièrement élevées ou de faible surface disponible. Enfin, l'étude de l'hydrodynamique montre que l'écoulement, ainsi que l'adsorption et les réactions de biodégradation, sont fortement influencés par la limitation du débit de fuite (temps de rétention, particulièrement pendant la phase saturée). Par ailleurs, la structure d'alimentation doit permettre une répartition homogène de l'influent à la surface du massif pour éviter les court-circuits hydrauliques et les volumes morts. La construction d'un modèle 1D a enfin été mise en oeuvre, mais celui-ci ne permet pas de faire des prédictions, car la couche virtuelle simulant la limitation du débit de fuite doit être calée lors de chaque événement simulé. Une adaptation 2D du modèle, la prise en compte de lois de vannes et pertes de charges singulières, ainsi qu'un couplage filtre-réseau doit permettre la finalisation de cet outil. / Urban runoff management has become a priority for many years, regarding the issues of flooding and water course pollution that jeopardize the objectives of the European Framework Directive 2000/60/CE. As an extensive technique, subsurface flow constructed wetlands have proved to be reliable solutions for the treatment of sewage, and have been used for more than 20 years. Their adaptation to other types of functions or effluents has even been implemented over the last ten years (tertiary treatment, dilute effluents, sludge drying reed beds), and the management of urban runoff is part of this extension process. Despite this system combines both storage and treatment capacities, (Uhl and Dittmer, 2005) highlight dysfunctions as reed death during long rest periods or performance losses. These authors also underline the needs in optimizing design rules and tools.Then, the SEGTEUP project combines a large-scale pilot monitoring and hydrodynamic modeling, aiming at providing some basis for the implementation of a reliable design tool, applicable over the entire French territory. Then, the pilot study aimed at testing different materials and filter configurations, while a mechanistic approach was implemented to highlight the main flow influence parameters.Anyway, filtration of suspended solids appears as the major pollutant removal process, allowing the retention of at least 70% of SS and associated pollutants whatever the material considered. Nevertheless, dissolved organic matter adsorption remains negligible, while ammonium elimination is poor for the coarsest material. In the opposite, adsorbent zeolite present high ammonium retention abilities and ensures constantly low discharge levels. The use of this material is particularly recommended in case of specific issues concerning high pollutant loads or low available surface area. Furthermore, micropollutants (metals and PAHs) mainly bound with particles, are highly removed by filtration of SS. In our study, dissolved micropollutants concentrations were too low to highlight robust conclusions. However, further research are needed to better understand metals retention and release, and PAHs degradation processes, since these mechanisms are strongly dependent of pH and redox conditions and dynamics. Finally, the study of hydrodynamics shows that the throttle value influences adsorption and degradation reactions through variations in hydraulic retention time, particularly during saturated phases. On the other hand, the feeding structure is of special importance since a homogenous distribution of influent at the filter surface is needed to avoid hydraulic shortcuts and corresponding dead volumes. Finally, a HYDRUS 1D model was implemented around urban runoff issues, but cannot be used as a predictive design tool. Indeed, the throttle value, represented by a virtual layer with low conductivity, must be re-calibrated for each simulated event. Then, a 2D adaptation of the model is required, as well as the integration in the HYDRUS code of appropriate singular head losses as boundary conditions. In the end, the developed simplified model of water flow and pollutant degradation should be coupled with a sewer system model, aiming at creating a flexible and adaptable design tool.

Climate changes brought on by global warming are expected to have a significant affect on the Pacific Northwest hydrology during the 21st Century. Current research anticipates higher mean annual temperatures and an intensification of the hydrological cycle. This is of particular concern for highly urbanized basins, which are considered more vulnerable to changes in climate. Because the majority of previous studies have addressed the influences of either climate or urban land cover changes on runoff, there is a lack of research investigating the combined effect of these factors. The Rock Creek basin (RCB), located in the Portland, OR, metropolitan area, has been experiencing rapid urban growth throughout the last 30 years, making it an ideal study area for assessing the affect of climate and land cover changes on runoff. Methods for this assessment include using a combination of climate change and land cover change scenarios for 2040 with the semi distributed AVSWAT-X (Arc View Soil and Water Assessment Tool) hydrological model to determine changes in mean runoff depths at the monthly, seasonal, and annual scales. Statistically downscaled climate change results from the ECHAM5 general circulation model (GCM) found that the region would experience an increase of 1.2°C in the average annual temperature and a 6% increase in average annual precipitation between 2030 and 2059. The model results revealed an amplification of runoff from either climate or urbanization. Projected climate change plus low-density, sprawled urban development for 2040 produced the greatest change to mean annual runoff depth (+5.5%), while climate change plus higher-density urban development for 2040 resulted in the smallest change (+5.3%), when compared to the climate and land cover of 2001. The results of this study support the hypothesis that the combination of both climate change and urbanization would amplify the runoff from the RCB during the 21st Century. This has significant implications for water resource managers attempting to implement adaptive water resource policies to future changes resulting from climate and urbanization.

Bibliography: leaves 84-91. Examines the current status of urban stormwater and water resources management in Vietnam

The aim of this dissertation was to develop a multi-criteria decision support system (MCDSS) to allow a specified manager to select with confidence one or many of these BMPs for a particular site. The principal design approach was a review of South African and international literature pertaining to stormwater management techniques, in particular BMPs. This information was formulated into a primary matrix using a rank-and-weighting method. The scores were then checked against the literature to ensure that they were reasonable, culminating in the initial MCDSS. The MCDSS was then provided with seven scenarios, described in the literature, and the output reviewed. Although, the MCDSS would select appropriately when given few criteria for selection when these were increased, inappropriate outcomes resulted. Consequently, weighting factors were assigned to each criterion. The MCDSS was further tested using all the selection criteria and the output deemed satisfactory. The MCDSS was then tested in a case study of the Town Bush stream catchment at eleven sites along the river network and the results were adequate. Taking into consideration the economic aspects of BMP implementation a need also arose for the sites to be allocated to certain authorities depending upon ownership or responsibility. The sites were prioritised depending on potential threat to property and lastly by the hydrological nature of the stream at each site. A stormwater plan for the study area was also proposed. Although the MCDSS was functioning adequately it was not without its limitations. Limitations included the use of drainage areas as a surrogate measure for peak discharge thus, not allowing the user to design a series of BMPs or treatment chain. A second limitation was that initially the BMPs were designed as offline systems where stormwater is managed before entering the channel but in this study they were used as inline systems. Hence the ultimate selection was biased towards those BMPs able to deal with large drainage areas. Recommendations for further improvement include the development of a surrogate measure for drainage area thus allowing the user to design a treatment chain of BMPs; testing the MCDSS in more diverse circumstances; developing a more comprehensive set of selection criteria; and developing a clearer priority-setting model as the one used was rather simplistic. In conclusion the MCDSS provides the user with a useful tool where the selection and implementation of BMPs no longer has to take place in an ad hoc manner. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001

Nature provides essential services to humans, including climate regulation, water provisioning and regulation. These so-called ecosystem services have economical, societal and environmental value. This research aims at improving the knowledge on the linkages between selected hydrological ecosystem services and current and proposed land uses within the water-limited Mpushini/Mkhondeni Catchments in South Africa. The research contributes to the recognition of feedback and linkages within the complex ecological-human system, so that informed land use decisions can be made. The research aim is achieved by first reviewing the literature on hydrological ecosystem services, land use in an ecosystem services context and the links between the two. The study area is then sub-delineated into land use determined hydrological response units for baseline natural land cover, as well as for current and proposed land use scenarios. Using an appropriate model, selected hydrological processes are simulated in order to isolate the effects of individual land uses on hydrological responses, both on a local and a more catchment-wide scale. Various land uses were found to affect hydrological responses, such as runoff and its components of stormflows and baseflows, as well as transpiration and sediment yields, differently. These responses were found to be suitable indicators of selected ecosystem services such as water provisioning or flow regulation. Irrigation and high biomass crops, such as sugarcane and wattle plantations were found to reduce downstream water provisioning services. Degraded lands were found to reduce physical water quality through increased sediment yield, to reduce water provisioning during low flow periods, while the degraded lands increased stormflows, thereby reducing regulation of high flows. Urban land uses were found to significantly increase runoff, with increased impervious areas causing a shift from evaporation and transpiration towards runoff. Stormflows increased, with high flow regulation being reduced. Baseflows increased as well, as a result of a spill-over of runoff from impervious to pervious urban areas, which led to increased low flow regulation. In addition, in this study area urban return flows are generated from externally sourced water, further increasing streamflows and especially low flows. While urban areas showed an increase in downstream water quantity provision, the water quality was reduced. The combined effects of the current land use mosaic on the annual streamflows partially cancel each other out, while the proposed urbanisation dominated hydrological responses. Influences of various land uses on hydrological ecosystem services were thereby shown, which contributes to a better understanding of the linkages between the two. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

Sewage misconnections currently pose severe threats to water quality especially in urban areas in the UK. These misconnections lead to the discharge of untreated wastewater into receiving watercourses via surface water outfalls. Regular discharges from this source could lead to these watercourses failing to meet standards set by the Water Framework Directives. Despite the impacts resulting from this urban diffuse pollutant source, research into this area is limited. The study area is the River Lee, which is known to experience issues with water quality especially within the heavily urbanized lower Lee section. Misconnections are one of the major contributors to the poor water quality status of the River. In this study, the Lee was investigated using several parameters. The approach involved the monitoring of coliform bacteria to detect outfalls where misconnections were likely, then biofilm samples below selected outfalls were used for both clean and polluted sites to look for community types. Results showed severe pollution within some sections of the River particularly within the lower Lee. Pymmes Brook was used as a case study, both coliform bacteria and biofilm communities below outfalls were further investigated for clean and polluted sites. Results from the Pymmes Brook study also showed that this watercourse was experiencing severe issues with water quality, with elevated levels of coliform bacteria identified below polluted outfalls. Biofilm community data obtained during the pilot and experimental phases of study were analyzed using a range of multivariate techniques. Results of the analysis showed consistent x patterns in community structure within sites with similar water quality, with indicator species identified. Communities below polluted outfalls were composed mainly of species tolerant of organic pollution thus indicating a response of communities to misconnection discharges. Currently, the identification of misconnections are carried out through trackbacks, a process which is expensive and time consuming. During this study an inexpensive and rapid approach is proposed for assessing misconnections within a catchment. Using this method, misconnection hotspots are mapped out using coliform bacteria and biofilm communities. Using catchment data and predicted coliform bacteria from enumerated counts, misconnections within these hotspots are assessed. Having tested this approach on Pymmes Brook, a tributary of the River Lee, the results obtained were promising. Pending further verification, this system provides an economical and rapid tool for the assessment of misconnections within a catchment.

The thesis covers the investigation of the storm water runoff and artificial recharge components of the Atlantis Water Resource Management Scheme in the Southwestern Cape. The objective of the study was to obtain an in-depth knowledge of the process of artificial recharge of urban storm water runoff, in order to identify the most efficient recharge management strategy for the Atlantis aquifer. To achieve the objective it was necessary to first study the existing knowledge on urban storm water hydrology and artificial recharge by spreading, and to create a conceptual model of what might be expected. The study area was then investigated to examine how closely the actual situation was reflected by the conceptual model, enabling recommendations to be made for the sound management of the system. The stormwater runoff component was found to differ from most urban hydrological studies as a result of its large baseflow component. The sandy nature of the catchment, small percentage area of effective impervious surface, and high groundwater table resulted in the baseflow constituting more than 40% of the total storm water runoff and accounting for over 60% of the pollution load. The "first flush" effect established as a major source of pollution in other studies, was found to be of minor significance in this study area. The overall stormwater quality (excluding the noxious industrial baseflow) was found acceptable for artificial recharge within the study area, although the baseflow from the industrial sub-catchments showed the potential for being a major source of pollution in the future. The treated wastewater used for artificial recharge prior to 1987 was found to be unacceptable for recharge purposes. The treated industrial effluent should under no circumstances be recharged up-gradient of the Witzand well field. The treated domestic effluent although of a poorer quality than the resident Witzand well field groundwater could be recharged in order to boost recharge volumes and form a buffer against further intrusion by the poor quality groundwater from the Brakkefontein area. This would however only be acceptable if strict water quality control is maintained and recharge does not take place west of the present basin. The recharge basin was found to be well situated with respect to influencing the Witzand wellfield and maintaining a groundwater buffer against poor quality groundwater flow from the northeast towards the central area of the wellfield. Unfortunately the surrounding low-lying topography and sandy retaining walls have resulted in return flow and raised groundwater-levels. The raised groundwater mound does not comply with the conceptual model and together with the sandy nature of the unsaturated zone resulted in less effective purification during infiltration. The practice of letting large portions of the basin floor dry-out during summer was shown to be beneficial and the periodic cleaning of the deeper portions of the basin essential. The artificially recharged water was found to have influenced the upper portion of the aquifer well beyond the West Coast Road. The study of groundwater quality being a good method for tracing artificially recharged water. The groundwater quality has improved as a result of artificial recharge since the removal of treated wastewater from the recharge basin. The groundwater was (ii) found to be very responsive to the slightest changes in recharge basin water quality or/and quantity. Management of the recharge basin therefore had to be very much of a compromise between qualitative and quantitative approaches. The present approach of recharging all the stormwater runoff throughout the year providing the most efficient compromise under the present conditions. The study revealed that the most efficient recharge management strategy would be the recharge of treated domestic sewage effluent in the present recharge basin and all residential storm water runoff plus industrial "storm flow" stormwater runoff in a new recharge basin located northwest of the present basin. Strict water quality control must be maintained on the water discharged into the basins and an annual wet/dry cycle implemented within the basins to boost infiltration. The entire system should continue being monitored to safe guard the groundwater resource from pollution and over exploitation.

Public health impacts of storm water canals in Nelson Mandela Bay communities

This work involves the study of the effects of land use on the chemical composition of urban stormwater runoff, and its subsequent acute toxicity to the aquatic invertebrate Daphnia pulex. Samples were obtained from the Brunette drainage basin of Burnaby, British Columbia, from a variety of sites in the land use classifications commercial (C), industrial (I), residential (R) and open/greenspace (0). Results indicate that the toxicity to D. pulex and the chemical composition of the stormwater (measured by such parameters as COD, alkalinity, hardness, hydrocarbons and trace metals) were influenced by land use and the interval between rainfall events. The industrial and commercial land use sites were the major source of those trace metals most often considered toxic to aquatic organisms, with runoff from the commercial sites proving most toxic to the test organism (toxicity followed the sequence C>I>R»0). Bioassays with synthetic stormwater (Cu, Fe, Pb and Zn, at concentrations observed from field samples) demonstrated that pH and suspended solids helped to regulate the toxicity of the trace metals, and implicated the importance of these elements in natural stormwater toxicity. Statistical comparison between synthetic and natural stormwater runoff toxicity yielded poor correlation; however, this was expected due to the inherent differences between the laboratory and field environments. A detailed study of a single storm event indicated that while the "first-flush" of the storm may be contributing to toxicity through the physical scouring of insoluble pollutants, the soluble pollutants proved to be more toxic and were washed out of the area over the entire duration of the event. This prompted the author to propose the complete treatment of all stormwater runoff, and not simply the slug load of the first hour. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate