Laboratory experiments were conducted to investigate the velocity and turbulence characteristics in flows through rigid vegetation. The vegetation was simulated by an array of acrylic dowels mounted to the bed of a recirculating hydraulic flume. Velocity measurements were taken in both the longitudinal and vertical directions using a one-dimensional laser doppler velocimeter (LDV). Experiments were conducted under partially submerged, fully submerged and double layer flow conditions. The term double layer flow is used to describe flows that contain two different heights of vegetation. In each experiment, velocity and turbulence intensity profiles were taken at several different locations within the array. Additional experiments were conducted to examine how bed and vegetative skin roughness influence the velocity and turbulence characteristics. Belt sander strips were glued to the bed of the flume to simulate bed roughness and adhesive sandpaper was attached to the dowels to simulate vegetative skin roughness. Finally, experiments were conducted to study sediment transport and deposition in flows containing vegetation. / Master of Science

Yes / Peatlands have often been represented in cultural material as being dangerous and inhospitable places, partly based on post-medieval influences, but also partly based on elements of folklore which emphasise the ‘other-worldly’ and liminal nature of these environments. Using Ilkley Moor, West Yorkshire, as a case study, the role of heritage, folklore and cultural media in guiding perceptions of the landscape is explored. Contemporary society is more diversified than historic situations, and our review indicates that perceptions of heritage landscapes reflect this complexity. The use of the peatland by different groups is explored, before addressing the interconnected roles of folklore and archaeology in past, present and future engagement with this landscape. / JP-ICH under Grant number AH/S006427/1.

This comparative study explores the mechanisms of pollutant removal efficiency in cold-climate constructed wetlands (CWs) and investigates the benefits, standing and practicability of using these systems to treat wastewater in Canada and Northern China. Treatment efficiencies defined by the Canadian and Northern China experience vary considerably. Experience in both countries shows that the majority of effluent values are generally better than that required by discharge standards in Canada and China. A review of the available case studies on cold weather treatment in both countries indicates that this technology is feasible in Canada and Northern China, although further monitoring data are needed to optimize CW design and ensure that the effluent quality standards are consistently met. In both of these countries and around the globe, increasingly strict water quality standards and the growing application of treatment wetlands for wastewater treatment is an important motive for the development of better numerical models as predictive process design tools. An investigation of the SubWet 2.0 model, a horizontal subsurface flow modeling program used to predict the level of treatment that can be expected was conducted. It has been shown that SubWet can consider the influence of several factors at one time, where empirical equations are generally not able to consider more than two factors at one time and usually in isolation of the other influential parameters. Three different data sets, two from natural wetlands from the Canadian Arctic and one from a CW in Africa were used to illustrate how SubWet can be calibrated to specific wetlands. Compared to other models, it is suggested that SubWet provides one of the best modeling options available for natural tundra wetlands. Further calibration of SubWet with twelve municipal treatment wetlands in the Canadian Arctic clearly demonstrated its ability to model treatment performance within natural tundra wetlands and thus provide an additional predictive tool to aid northern stakeholders in the treatment of municipal effluents. It is anticipated that increased monitoring and the generation of additional measured data will help to better identify the level of year to year variability and improve the overall predictive capability of the model. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-10-22 17:14:23.322

As wetlands construídas estão entre as tecnologias eficientes recentemente comprovadas para tratamento e polimento de águas residuárias. Comparando com os sistemas convencionais de tratamento, são de baixo custo, fácil operação e manutenção. Esta pesquisa objetivou avaliar estudos de caso nacionais de utilização de wetlands para tratamento de efluentes em nível terciário com a finalidade de efetuar a remoção de nutrientes, buscando estabelecer parâmetros técnicos, operacionais e de manutenção. Foram avaliados sistemas que utilizaram como macrófita: Typha, Vetiver zizanioides L.Nash, Colocasia esculenta, Hedychium coronarium, Heliconia psittacorum, and Cyperus alternifolius; através de fluxos superficial e subsuperficial; o material filtrante foi brita e areia e o tempo de detenção hidráulica variou de 1,1 a 5 dias. Os resultados encontrados variaram de 5,6 por cento a 93,9 por cento para remoção de nitrogênio amoniacal e de 5 a 90,5 por cento para remoção de fósforo total. Constatou-se que a discrepância entre os resultados está associada ao tempo de detenção hidráulico utilizado, tipo de fluxo escolhido, material filtrante e manejo das macrófitas. Concluiu-se que a wetland construída pode ser usada como tratamento de efluentes em nível terciário para remoção de nutrientes, podendo-se afirmar que: a escolha da combinação de macrófita, material filtrante e fluxo deve ser feita de acordo com o efluente a ser tratado; não há um definição quanto ao tempo de detenção hidráulica ideal para cada sistema o que indica a necessidade de instalar pilotos para avaliação antes de implementar as estações em escala real; a poda deve ser feita respeitando o ciclo de desenvolvimento de cada espécie; é necessário realizar pesquisas que monitorem o sistema a longo prazo para avaliar o seu comportamento. / The constructed wetlands are among of the recently proven efficient technologies for treating and polishing of wastewater. Compared to conventional treatment systems, they are low cost, easily operated and maintained. This study aimed to evaluate national case studies of use of wetlands as a tertiary stage of wastewater treatment in order to make the removing of nutrients and establish technical, operational and maintenance parameters. The evaluated systems used as macrophyte: Typha, Vetiver zizanioides L.Nash, Colocasia esculenta, Hedychium coronarium, Heliconia psittacorum, and Cyperus alternifolius; through surface and subsurface flows; the filter material was gravel and sand and the hydraulic retention time ranged from 1.1 to 5 days. The results ranged from 5.6 per cent to 93.9 per cent for ammonia removal and from 5 to 90.5 per cent for total phosphorus removal. It was found that the discrepancy between the results is associated to the use of hydraulic detention time, to the type of flow, filter material and management of macrophytes. It was concluded that the constructed wetland can be used as tertiary stage of wastewater treatment for nutrients removal, it´s possible to say that: the combination between macrophyte, flow and filter material should be made in accordance with the effluent to be treated ; there is no definition as to the optimal hydraulic retention time for each system indicating the need to install a pilot treatment for evaluation before implementing the seasons full-scale; pruning should be done respecting the development cycle of each species; studies should be conducted to monitor the long-term system to evaluate their behavior.

Global trends of transformation and loss of wetlands to other land uses has deleterious effects on surrounding ecosystems, and there is a resultant increasing need for improved mapping of wetlands. This is because wetland conservation and management depends on accurate spatial representation of these systems. Current approaches to mapping wetlands through the classification of satellite imagery typically under-represent actual wetland area, and the importance of ancillary data in improving the accuracy in mapping wetlands is recognized. This study uses likelihood estimates of wetland occurrence in KwaZulu-Natal (KZN), South Africa, using a number of environmental surrogate predictors (such as slope, rainfall, soil properties etc.). Using statistical information from a set of mutually independent environmental variables in known wetland areas, conditional probabilities were derived through a Bayesian network (BN) from which a raster layer of wetland probability was created. The layer represents the likelihood of wetlands occurring in a specific area according to the statistical conditional probability of the wetland determinants. Probability values of 80% and greater also accounted for approximately 6% of the KZN area (5 520 km²), which is substantially more than the previously documented wetland area in KZN (4% of the KZN area or 4 200 km²). Using an independent test dataset, Receiver Operating Characteristic (ROC) curves with the Area Under Curve (AUC) analysis verified that the final model output predicted wetland area well (AUC 0.853). Based on visual comparisons between the probability layer and ground verified wetland systems, it was shown that high wetland probability areas in the final output correlated well with previously highlighted major wetland and wetland-rich areas in KZN. Assessment of the final probability values indicated that the higher the probability values, the higher the accuracy in predicting wetland occurrence in a landscape setting, irrespective of the wetland area. It was concluded that the layer derived from predictor layers in a BN has the potential to improve the accuracy of the KZN wetland layer by serving as valuable ancillary data. Application of the final probability layer could extend into the development of updated spatial freshwater conservation plans, potentially predicting the historical wetland extents, and as input into the land cover classification process. Keywords: ancillary data, Bayesian network, GIS, modelling, probability, wetland mapping. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

As wetlands construídas estão entre as tecnologias eficientes recentemente comprovadas para tratamento e polimento de águas residuárias. Comparando com os sistemas convencionais de tratamento, são de baixo custo, fácil operação e manutenção. Esta pesquisa objetivou avaliar estudos de caso nacionais de utilização de wetlands para tratamento de efluentes em nível terciário com a finalidade de efetuar a remoção de nutrientes, buscando estabelecer parâmetros técnicos, operacionais e de manutenção. Foram avaliados sistemas que utilizaram como macrófita: Typha, Vetiver zizanioides L.Nash, Colocasia esculenta, Hedychium coronarium, Heliconia psittacorum, and Cyperus alternifolius; através de fluxos superficial e subsuperficial; o material filtrante foi brita e areia e o tempo de detenção hidráulica variou de 1,1 a 5 dias. Os resultados encontrados variaram de 5,6 por cento a 93,9 por cento para remoção de nitrogênio amoniacal e de 5 a 90,5 por cento para remoção de fósforo total. Constatou-se que a discrepância entre os resultados está associada ao tempo de detenção hidráulico utilizado, tipo de fluxo escolhido, material filtrante e manejo das macrófitas. Concluiu-se que a wetland construída pode ser usada como tratamento de efluentes em nível terciário para remoção de nutrientes, podendo-se afirmar que: a escolha da combinação de macrófita, material filtrante e fluxo deve ser feita de acordo com o efluente a ser tratado; não há um definição quanto ao tempo de detenção hidráulica ideal para cada sistema o que indica a necessidade de instalar pilotos para avaliação antes de implementar as estações em escala real; a poda deve ser feita respeitando o ciclo de desenvolvimento de cada espécie; é necessário realizar pesquisas que monitorem o sistema a longo prazo para avaliar o seu comportamento. / The constructed wetlands are among of the recently proven efficient technologies for treating and polishing of wastewater. Compared to conventional treatment systems, they are low cost, easily operated and maintained. This study aimed to evaluate national case studies of use of wetlands as a tertiary stage of wastewater treatment in order to make the removing of nutrients and establish technical, operational and maintenance parameters. The evaluated systems used as macrophyte: Typha, Vetiver zizanioides L.Nash, Colocasia esculenta, Hedychium coronarium, Heliconia psittacorum, and Cyperus alternifolius; through surface and subsurface flows; the filter material was gravel and sand and the hydraulic retention time ranged from 1.1 to 5 days. The results ranged from 5.6 per cent to 93.9 per cent for ammonia removal and from 5 to 90.5 per cent for total phosphorus removal. It was found that the discrepancy between the results is associated to the use of hydraulic detention time, to the type of flow, filter material and management of macrophytes. It was concluded that the constructed wetland can be used as tertiary stage of wastewater treatment for nutrients removal, it´s possible to say that: the combination between macrophyte, flow and filter material should be made in accordance with the effluent to be treated ; there is no definition as to the optimal hydraulic retention time for each system indicating the need to install a pilot treatment for evaluation before implementing the seasons full-scale; pruning should be done respecting the development cycle of each species; studies should be conducted to monitor the long-term system to evaluate their behavior.

In many of the rural areas of South Africa local communities rely on wetland resources for daily living. For a symbiotic relationship to exist between these communities and the wetlands, the wetlands must be utilised in a manner sustainable to both parties. To prevent exploitation thereof, a comprehensive understanding of the processes and functions of wetlands, of the values and needs of rural community members, and of the interactions between these entities is essential. This study focuses on research at three scales; the plot scale (10m\ the microcatchment scale (lkm2 ), represented by the Craigiebum wetland and microcatchment, and the catchment area upstream of the gauging weir X3H008, all of which exist in the Sand River catchment in the Mpumalanga and Limpopo Provinces of South Africa. Relationships between the geomorphological properties of the Craigiebum microcatchment, the wetland management practices of the local communities, and the hydrological properties of the microcatchment have been investigated. Various hydrological models, but in the main the ACRU model, have been adopted as tools to facilitate this research. Possible scenarios of changes in land use, rainfall and soil texture were performed at the plot scale and at the scale of the microcatchment, and changes in wetland extent were simulated and analysed at the scale of the catchment. Results of the modelling exercises simulating the effects of differences in soil texture higWight the positive effects of retention of fine particles within a wetland in a sandy environment. These results also depict greater rates of hydraulic conductivity, erosion and desiccation within coarse-textured soils than fmer textured soils. Low levels of fertility can also be attributed to the lack of fine particles present in the soils of the Craigiebum microcatchment wetland. Results of the modelling exercises that investigate the likely hydrological effects of a variety of land uses within the Craigiebum microcatchment verify accepted hydrological theory, as they highlight that more impervious areas produce more stormflow and lose more water to evaporation, and that the natural vegetation of the area contributes to streamflow regulation more than other land uses do. The exercises performed at the scale of the Sand River catchment do not provide conclusive evidence of the effects of changes in wetland extent, as the hydrological effects that other land uses in the area have appear to override the effects of the simulated wetland areas. Analysis of the sociological data captured highlights the great extent to which the local community depends on the Craigieburn wetland resources for a variety of livelihood strategies. Furthermore it illustrates the degree to which a reduction in wetland health negatively impacts upon the community. Viewed in conjunction, the hydrological, biophysical and sociological results highlight the degree to which changes in one aspect of the environment affect other aspects thereof, thereby highlighting the degree to which these aspects of the Craigieburn microcatchment are inextricably linked. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

The study sheds light on the occurrence and development of earth mounds in the Mkhuze Wetlands, KwaZulu-Natal. It compares this system with the Okavango Delta. The conceptual model developed by Ellery and co-workers for mima mound development in the Okavango Delta is said to have worldwide applicability (Ellery at al. 1998). This study investigates the applicability of this model in the formation and development of earth mounds in Mkhuze Floodplain. The activities of termite species are regarded as responsible for the formation of earth mounds in the Okavango Delta. The Mkhuze Wetlands represent one of South Africa’s most pristine wetland systems (Cowan 1995). They have also been declared as part of the Isimangaliso Park, a World Heritage Site (Cowan 1995). Many studies have been conducted in Mkhuze Wetlands in order to gain more knowledge and understanding of how the system functions, so that it can be managed wisely. Although termites are thought to be associated with these features (Adams 2004), very little has been done to assess or even verify if the changes in soil chemistry and mineralogy across these mounds can be linked to termite activities. This study investigates the soil mineralogy and physico-chemical properties across mounds found in the Mkhuze Wetlands and determines through its findings any possible link to termite activities. Most mounds in Mkhuze were identified in the intermittently flooded region of the floodplain. Results from particle size analysis were indicative of a bimodal distribution in mound soils. Two major components in mounds were a combination of clay size particles, silts and very fine sand, and fine to medium sand, with traces of coarse sand. There was a significant difference in the distribution of soil particle size fractions found on mounds compared to soils adjacent to the mounds. The chemical composition of the clay size particles found on the mounds was different when compared to that found in adjacent soils. There were also higher concentrations of minerals derived from solute chemicals found in the centre of the mounds at depth. Precipitation of solutes in mid regions of the mounds is thought to attest to spatial evapotranspiration rates across mounds. Although no direct evidence of termites was found in the mounds, there are indications that termites have been responsible for the development of the mounds and that in certain mounds plants have led to mound growth due to precipitation of solutes driven by evapotranspiration. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

A utilização de métodos naturais, do tipo leitos cultivados, para a redução de poluentes tem mostrado resultados satisfatórios que o tornam viáveis para diversos segmentos da sociedade. Instituições de ensino possuem calendários acadêmicos que incluem longos períodos de recesso que leva o fluxo de esgoto nos sistemas praticamente a zero causando graves danos tanto para as colônias de micro-organismos as macrófitas associadas. O presente estudo teve por objetivo avaliar a eficiência de um sistema de leito cultivado, em uma instituição de ensino, logo após período de recesso, verificando se o mesmo apresentava sinais de recuperação sem qualquer intervenção e em seguida com uma manutenção. Para avaliar a eficiência do tanque de leito cultivado a metodologia adotada baseou-se nos parâmetros físico-químicos e microbiológicos de análise da água em um sistema de fluxo subsuperficial. A eficiência de remoção para os parâmetros de turbidez, NH3, NO3- e Fósforo foram respectivamente de 63%, 21,69%, 31,05% e 20,27%, para DBO, DQO e coliformes termotolerante os respectivos valores da eficiência média foram de 45,99%, 29,72% e 44,01%. Se for considerado apenas o período pós-intervenção os resultados melhoram, sendo os seguintes: turbidez=78,17%, NH3=37,95%, NO3 -=53,18%, Fósforo=25,56%, DBO=66,15%, DQO=36,50% e coliformes termotolerantes=60,72%. Os resultados demonstram a importância da vegetação na qualidade da eficiência desse tipo de sistema. / The utilization of natural methods to reduce pollutants, like wetland, has shown satisfactory results which make it viable for different segments of society. Educational institutions have academic calendars that include long periods of recess which takes the flow of sewage systems practically zero causing serious damage both for microorganisms as for the associated macrophytes. The present study had as it goal to evaluate the wetland system efficiency, after the recess period of an educational institution, checking if it showed signs of recovery without any intervention, and then with a maintenance. In order to evaluate the efficiency of the wetland pool the adopted methodology was based on physico-chemical and microbiological parameters of water analysis in a subsurface flow system. The removal efficiency for the parameters of turbidity, NH3, NO3- and phosphorus were respectively 63%, 21.69%, 31.05% and 20.27%, for DBO, DQO and thermotolerant coliforms the several values of average efficiency were 45.99%, 29.72% and 44.01%. If it was considered only the period after intervention, the results get better, being the following: turbidity=78,17%, NH3=37,95%, NO3 -=53,18%, phosphorus=25.56%, DBO=66.15%, DQO=36.50% and thermotolerant coliforms=60.72%. The results show the importance of vegetation on the quality of efficiency of this kind of system.

No description available.