This paper evaluates the effectiveness of the institutional framework of the Commonwealth of Virginia in the implementation and enforcement of nonpoint source (NPS) pollution control measures in the state's urbanizing areas. The institutional framework is developed primarily around the existing governmental framework. The federal, state and local roles are examined in terms of the relevant legislative and executive NPS control activities already taking place. The judicial function is considered in terms of constitutional guarantees of protection of private property and the potential for liability stemming from the implementation of structural and nonstructural best management practices (BMP's). Three generic categories of BMP's are evaluated in light of this institutional environment: on-site BMP's, off-site BMP's and nonstructural BMP's. Where they are relevant, various subcategories of the institutional environment are examined: mechanisms and responsibility for financing and maintenance, managing future urban growth and mediating interjurisdictional arrangements. The introduction and first four chapters develop this material and the final chapter is an analysis of the existing state programs (the Erosion and Sediment Control Law and the State Water Control Board's voluntary Urban NPS Control and Abatement Program). The product of this analysis is the conclusion that both state programs analyzed are weak due to a lack of state oversight. In addition, the Erosion and Sediment Control Program could be strengthened by amending the law to add a viable "stop work" order and by defining violations as being civil rather than criminal (misdemeanors) violations. / M.S.

Thesis (MPhil)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The particular global context that is fundamentally altering the world is one in which the combined resource requirements of cities are unprecedented. This thesis communicates the thoughts, ideas and research observations on contemporary urbanisation dynamics through a synthesis of various perspectives. This conceptual fusion, as an attempt to provide a holistic overview of contemporary urban dynamics, forms the basis for developing a framework from which the multiple dimensions of cities can be addressed. This theoretical framework, which includes empirical analyses on the state of cities, is then applied to Johannesburg as a case study for deepening the understanding of urban dynamics and to assess implementation of the theoretical framework in reality. Despite being guided by the general aims of investigating current urban growth trends and the conceptual frameworks with which urban systems could be better understood, the complexity of the task at hand defied a static and linear research process. The ideas that emerged through the research journey, as opposed to a process, were synthesised using a literature review from which the framework of managing complex social-ecological systems was developed. Central to this framework is the metaphor of resilience, which through the idea of systemic adaptability, prioritises the need for both social and ecological opportunity to be enhanced. This is critical in the face of cross-cutting global challenges and in terms of cities as archetypical complex social-ecological systems. In reviewing literature on contemporary urbanisation dynamics, it was found that the socio-economic, spatial and ecological tensions characterising developing country cities, require strategies to enhance urban resilience rooted in local social and ecological capabilities that differ from developed nations’ contexts. These practical concerns were the catalyst for suggesting green infrastructure as a framework in which the joint social and ecological values of green assets are valued equally. This in line with the logic of enhancing a system’s overall systemic adaptability. The theoretical frameworks included in the literature review, therefore, emerged through the weaving back and forth of thoughts, debates and practical concerns about creating resilience between people and nature in the urban landscapes of developing countries The methodological implications of a green infrastructure framework resulted in the need to determine the total economic value of ecosystem services, as the benefits that society accrues through ecosystem functioning. Valuing both the social and ecological benefits of such ecosystem derivatives, not only relates to the concept of mutual resilience building, but makes the economic case for investment in natural assets. Through experience with this methodology, it emerged that valuation exercises of ecosystem services require primary research that connects physical data on ecosystem functioning to tangible economic values. In the chosen case study, however, this original research is yet to take place and methodologies for valuing Johannesburg’s green assets had to unfold based on data availability. The development of a methodology within a methodology is a major feature of this paper, which is guided by the logic that for overall systemic resilience to be sustained, investment in natural assets needs to explicitly account for the total economic values of ecosystem services. The conclusions suggest that Johannesburg is nevertheless in a unique position to capitalise on the concept of green infrastructure, from which social and ecological opportunity can be mutually enhanced. In a paradoxical way, the city’s tree-planting boom that resulted in the construction of the world’s largest urban forest in natural savannah grassland, has created inventories of ecological and social resilience that represent the multifunctional value of green assets, if valued explicitly. Recognition of these values shows that ecological assets extend beyond publicly delineated open space and that Johannesburg’s culture of greening is potentially playing a significant role in sustaining the resilience between its people and nature. However, until the detailed base research is conducted on the connections between Johannesburg’s green assets and their associated social and ecological dividends, these assets remain potential inventories of resilience whose values are yet to be fully determined. The recommendations of this thesis are therefore largely to strengthen the research and data bases on Johannesburg’s green assets. Original research is needed so that precise valuation exercises of Johannesburg’s ecosystem services can take place. This research is also the foundation from which a more robust and empirically sound case can be made for motivating investment in Johannesburg’s strategically unique green infrastructure, in the context of social-ecological challenges and the global movement towards green economies, jobs and cities. / AFRIKAANSE OPSOMMING: Die spesifieke globale konteks wat die wêreld ten diepste verander, is ’n konteks waarin die gekombineerde behoeftes van stede ongekend is. Deur ’n samevatting van verskeie perspektiewe bied hierdie tesis gedagtes, idees en navorsingswaarnemings oor die hedendaagse stadsdinamika. Hierdie samevoeging van konsepte, as ’n poging om ’n holistiese oorsig van hedendaagse stadsdinamika te bied, vorm die grondslag vir die ontwikkeling van ’n raamwerk van waaruit die veelvuldige dimensies van stede benader kan word. Hierdie teoretiese raamwerk, wat empiriese analises van die stand van stede insluit, word dan toegepas op Johannesburg as ’n gevallestudie om die stadsdinamika beter te verstaan en die gebruik van die teoretiese raamwerk in die praktyk te evalueer. Die gedagtes wat uit die navorsing voortgespruit het, word saamgevat deur ’n oorsig te gee van literatuur waaruit die raamwerk vir die bestuur van komplekse sosio-ekologiese sisteme ontwikkel is. Die kern van hierdie raamwerk is die metafoor van weerstandsvermoë (“resilience”) wat, deur die gebruik van die konsep sistemiese aanpasbaarheid, die behoefte aan sowel meer sosiale as ekologiese geleenthede as die belangrikste prioriteite identifiseer. Dit is deurslaggewend in die lig van deursnee- globale uitdagings en in terme van stede as argetipiese komplekse sosio-ekologiese sisteme. In die oorsig van literatuur oor die hedendaagse stadsdinamika is daar gevind dat die sosio-ekonomiese, ruimtelike en ekologiese spanning wat stede in ontwikkelende lande kenmerk, strategieë vereis wat stadsweerstand, wat uit plaaslike sosiale en ekologiese vermoëns spruit, sal verhoog. Hierdie praktiese kwessies was die katalisator om ’n groen infrastruktuur voor te stel as die raamwerk waarbinne die gesamentlike sosiale en ekologiese waardes van groen bates ewe veel waarde dra, wat in pas is met die logiese gedagte om ’n sisteem se algehele sistemiese aanpasbaarheid te verhoog. Die teoretiese raamwerk wat ingesluit is in die literatuur wat bestudeer is, het dus na vore gekom deur die uitruil van gedagtes, debatte en praktiese benaderings tot hoe weerstandigheid geskep kan word tussen mens en natuur in die stedelike landskappe van ontwikkelende lande. Die metodologiese implikasies van ’n groen infrastruktuur-raamwerk het dit noodsaaklik gemaak om die totale ekonomiese waarde van ekosisteemdienste, as die voordele wat die samelewing deur ekosisteme ontvang, te bepaal. Die belangrikste navorsing om letterlike inligting oor Johannesburg se ekosisteemdienste aan tasbare ekonomiese waardes te verbind, moet egter nog gedoen word, en metodologieë om die stad se groen bates te evalueer moet ontwikkel word afhangende van die beskikbaarheid van inligting. Die ontwikkeling van ’n metodologie binne ’n metodologie is ’n belangrike kenmerk van hierdie tesis, wat gelei word deur die logiese gedagte dat belegging in natuurlike bates baie duidelik die totale ekonomiese waarde van ekosisteemdienste moet bepaal as algehele sistemiese weerstandsvermoë gehandhaaf wil word. Die gevolgtrekkings dui daarop dat Johannesburg nietemin in ’n unieke posisie is om finansiële voordeel uit die konsep van ’n groen infrastruktuur te trek. Op ’n teenstrydige manier het die stad se grootskaalse poging om bome aan te plant, wat gelei het tot die wêreld se grootste stedelike woud in ’n natuurlike grasvlakte, inligting gebied oor ekologiese en sosiale weerstandigheid, en dit verteenwoordig die multifunksionele waarde van groen bates as daar uitdruklik waarde daaraan geheg word. ’n Erkenning van hierdie waarde wys dat ekologiese bates verder strek as ’n openbare afgebakende oop ruimte en dat Johannesburg se groen kultuur moontlik ’n deurslaggewende rol speel om die weerstandsvermoë tussen sy mense en die natuur volhoubaar te maak. Voordat noukeurige grondnavorsing oor die verband tussen Johannesburg se groen bates en hulle gepaardgaande sosiale en ekologiese voordele egter nie uitgevoer is nie, bly hierdie bates potensiële beskrywings van weerstandsvermoë waarvan die waarde nog nie ten volle bepaal is nie. Die aanbevelings van hierdie tesis is daarom hoofsaaklik dat navorsing voortgesit word, en dat die kennisgrondslag van Johannesburg se groen bates verbreed word sodat ’n presiese evaluering van ekosisteemdienste gedoen kan word as die grondslag van sterker en empiries gestaafde redes om in die stad se groen infrastruktuur te belê.

Urbanization is known to have a negative impact on biodiversity. However, it is possible to increase bird species richness in cities through local actions such as increasing vegetation density and diversity. My first objective was to compare bird density and diversity on the island of Montreal among four urban habitat types: low-density and medium-density residential sectors, and residential and natural parks. A second objective was to determine the presence of bird species assemblages within these four urban habitats and a third was to explore associative relationships among six mainly shrub-nesting bird species and the vegetation they use. Point counts were conducted in each of 103 locations. Environmental variables measured consisted of the type (coniferous versus deciduous), density and height of vegetation within each 1 ha sector. Results revealed a decrease in bird abundance from medium-density residential habitats, residential park, low density residential habitats to natural parks and an increase in diversity from medium density residential habitats, low density residential habitats, residential parks to natural parks. Bird assemblages were determined through correspondence analysis. Most bird species were associated with at least one type of urban habitat. Associations between bird species and vegetation were measured through canonical correspondence analysis. The six focal species associated with shrubs demonstrated different levels of association with different habitat variables.

In this study, two different field experiments were designed to assess the relative influence of urbanization on benthic communities. During spring and summer, four urban and one reference sites from Denton County, Texas were selected for benthic macroinvertebrate evaluation. Statistically significant differences in colonized benthic macroinvertebrate taxa on artificial substrates were observed among the four urban sites and the reference site. Oligochaetes and chironomids were the dominant taxa at all sites. Identification of chironomid larvae at the subfamily and genus level to detect differences between sites had higher statistical power than the evaluation based on total chironomids. At the reference site, Caenis, Cladotanytarsus, Orthocladius, and Ceratopogonidae were the dominant taxa, while the urban sites were dominated by Dero, Physella, Ancylidae, Chironomus, Dicrotendipes, Glyptotendipes, Polypedilum, Pseudochironomus, Stenochironomus, and Tanytarsus. These differences may have been dependent upon differences in hydrologic regime and water quality between sites. Significant differences (ANOVA, p < 0.01) in water quality parameters (alkalinity, hardness, nitrates, phosphates, chlorides, sulfates, calcium, magnesium, potassium, and triazine) were found among water samples collected from the reference and urban sites. During the transfer period, most of the Ephemeroptera and Trichoptera taxa and a few other taxa disappeared from artificial substrates that were colonized at the reference site and then moved to the urban sites. Also, local abundant taxa from the urban site significantly (t test, p < 0.05) increased in number on the transferred artificial substrates. Seasonal differences in colonization patterns were also observed between the spring and summer experimental periods, which indicate that temporal variation is equally important, as is the anthropogenic effect in benthic community evaluation. Field survival and growth experiments using Erpetogomphus designatus larvae were designed to detect differences between evaluated sites. Larvae were collected from the reference site, measured in the laboratory, and exposed at the urban sites for six weeks in using specially designed cages. The exposed larvae demonstrated a higher mortality rate at the urban sites compared to the reference site.

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Natural vegetation has been converted to land uses, such as agriculture, commercial forestry and urban use, to meet increasing human demands for food, fuel and shelter. These land use changes modify the surface conditions of an area, resulting in changes in hydrological responses. Urban land use, in particular, has a significant impact on catchment hydrology as a result of the increased impervious areas such as concrete, tar and roofs. To assess the future hydrological impacts of urban land use, the scale and location of future urban areas must be considered. The objective of this study was to assess the hydrological responses to future urban growth in the Mgeni catchment, South Africa. An urban growth model was used to generate scenarios of plausible future urban growth and these scenarios were modelled using a hydrological model to determine the hydrological responses to urban growth. The plausible future urban growth in the Mgeni catchment was modelled using the SLEUTH Urban Growth model (SLEUTH). The SLEUTH acronym stands for the input layers required for the model viz. Slope, Land use, Excluded areas, Urban Extent, Transport routes and Hillshade. SLEUTH is able to provide the scale and location of future urban growth required to assess the hydrological impacts of future urban growth. The data requirements and modelling procedure for SLEUTH is relatively simply and therefore it is well suited to a South African context. SLEUTH was calibrated and applied to the Mgeni catchment to project future urban land use. When assessing the 95-100% probability class, the results revealed that the Henley, Pietermaritzburg and Durban areas would experience the highest urban growth in the Mgeni catchment by the year 2050. The outputs of the SLEUTH Model for the Mgeni catchment showed a number of similarities to another application of SLEUTH in Cape Town. These similarities indicate the SLEUTH performs in a similar way for the two South African cities. Therefore, it was concluded that the SLEUTH Model is suitable to account for urban growth in the Mgeni catchment, as required for use in hydrological impact studies. The hydrological responses to urban growth in the Mgeni catchment were assessed using the ACRU model. The scenarios of plausible future urban growth generated by SLEUTH were overlaid with current land cover layers to generate maps of plausible future urban land use. The results showed extensive urban growth of >95% probability occurring in the Midmar, Albert Falls, Henley, Pietermaritzburg, Table Mountain, Inanda and Durban Water Management Areas (WMAs) by 2050. Increases in mean annual streamflows were observed in many of these areas; however the Henley, Pietermaritzburg and Table Mountain WMAs were shown to have greater increases in mean annual streamflow than the other areas that showed similar increases in urban growth, thus indicating that these WMAs could be particularly responsive to urban growth in the future. Furthermore, the results showed that the type of urban land use is important in determining the hydrological responses of urban land use, as the imperviousness differs between the different urban land uses. Streamflow responses were shown to be influenced by the scale and location of urban growth in the Mgeni catchment and specific areas, such as the WMAs along the Msunduzi River, were identified as potentially responsive to urban growth. Summer streamflows were indicated as being more responsive to urban land use changes than winter streamflows and increases in streamflows due to urban growth start to over-ride the impacts of other land uses which have substantial impacts on hydrological responses such as commercial forestry, and commercial sugarcane by 2050, whereas in other areas increases were mitigated by the presence of major dams. Lastly, it was shown that the type of urban land use, such as built up urban areas when compared to informal urban areas for example, have a significant impact on streamflow responses. These results are useful as they can be used to inform both water resources planning as well as urban planning to ensure that South Africa’s valuable water resources are protected. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

This research project concerns changes in hydrology resulting from urbanization of the upper sub-basin of the White Rock Creek Watershed in Collin and Dallas Counties, Texas. The objectives of this study are: to calculate the percent watershed urbanized for the period of 1961 through 1968 and the period of 2000 through 2005; to derive a 1960s average unit hydrograph and a 2000s average unit hydrograph; and, to use the two averaged hydrographs to develop a range of hypothetical storm scenarios to evaluate how the storm response of the watershed has changed between these two periods. Results of this study show that stormflow occurs under lower intensity precipitation in the post-urbanized period and that stormflow peaks and volumes are substantially larger compared to the pre-urbanized period. It is concluded that changes in watershed surface conditions resulting from urbanization have lowered the precipitation-intensity threshold that must be surpassed before storm run-off is generated.

Bumble bees (Bombus spp.) are adept pollinators of countless cultivated and wild flowering plants, but many species have experienced declines in recent decades. Though urban sprawl has been implicated as a driving force of such losses, urban green spaces hold the potential to serve as habitat islands for bumble bees. As human populations continue to grow and metropolitan areas become larger, the survival of many bumble bee species will hinge on the identification and implementation of appropriate conservation measures at regional and finer scales. North Texas is home to some the fastest-growing urban areas in the country, including Denton County, as well as at least two declining bumble bee species (B. pensylvanicus and B. fraternus). Using a combination of field , molevular DNA and GIS methods I evaluated the persistence of historic bumble bee species in Denton County, and investigated the genetic structure and connectivity of the populations in these spaces. Field sampling resulted in the discovery of both B. pensylvanicus and B. fraternus in Denton County's urban green spaces. While the relative abundance of B. fraternus in these spaces was significantly lower than historic levels gleaned from museum recors, that of B. pensylvanicus was significantly higher. Statistical analyses found that both bare ground and tree cover surrounding sample sites were negatively associated with numbers of bumble bee individuals and hives detected in these green spaces. Additionally, limited genetic structuring of bumble bee populations was detected, leading to the conclusion that extensive gene flow is occurring across populations in Denton County.