Over the last millennium peatlands have accumulated significant carbon stores. Drainage for agricultural use has been widespread and has altered the functioning of these mires: shifting them towards carbon release. Recently, in recognition of the range of ecosystem services derived from these landscapes peatland restoration projects have been initiated. Carbon storage is often cited amongst the aims of these projects, especially since the inclusion of rewetting wetlands in the Kyoto Protocol. However, little is known about the effects of ditch blocking on CO2 fluxes, particularly in Molinia caerulea dominated peatlands, a species common on degraded peatlands which tolerates a range of water table depths. This thesis aims firstly to quantify CO2 fluxes from a drained Molinia caerulea dominated blanket bog and to improve understanding of the temporal and spatial controls on these fluxes and secondly, to quantify the immediate effects of ditch blocking. Closed chamber measurements of net ecosystem exchange and partitioned below-ground respiration from control-restored paired sites were collected over the growing seasons immediately pre- (2012) and post-restoration (2013/2014). These flux data were coupled with remotely sensed data quantifying vegetation phenology and structure with a fine resolution (daily/cm) over large extents (annual/catchment). Although temporal variation in water table depth was not related to CO2 fluxes, the seasonal average related to vegetation composition suggesting raising water tables may promote a change in vegetation composition within these species-poor ecosystems. The distribution of water table depths, vegetation composition and CO2 fluxes did not vary with proximity to drainage ditches despite their prominence. An empirical model suggests in a drained state these peatlands are CO2 sources, indicating carbon previously accumulated is gradually being lost. Data suggest restoration does not always significantly affect water tables and consequently CO2 fluxes in the short-term. Where shallower water tables were maintained during dry conditions photosynthesis decreased and heterotrophic respiration increased: enhancing carbon release. Research undertaken during atypical weather has been unable to determine if restoration will be able to raise water tables sufficiently to protect the existing peat store and promote the vegetation change required to reinstate CO2 sequestration in the longer-term.

In the agricultural Midwest, subsurface drainage allows excess water to drain into agricultural channels, which flows into rivers and streams transporting excess nutrients downstream. The construction of an inset floodplain within agricultural channels enhances sedimentation of particulate nutrients and sediment, provides stable conditions for vegetation to establish, increases rates of microbial activity, and promotes denitrification. Sediments were collected from floodplains of two-stage channels and naturally forming floodplain benches in conventional channels to determine the effect of floodplain creation on carbon and nitrogen cycling. Denitrification rates were seasonally measured across the floodplain width using an unamended acetylene inhibition technique (DNFAIT). Composite respiration and denitrification rates were measured through sacrificial microcosms utilizing membrane inlet mass spectrometry (DNFMIMS). While the two-stage reach showed a significant increase in soil organic matter (two-way ANOVA, p < 0.001) and respiration rates (two-way ANOVA, p = 0.039), there was no effect on DNFMIMS rates (two-way ANOVA, p > 0.05). DNFAIT rates at the two-stage reach only showed an increase at locations closest to the channel (two-way ANOVA, p = 0.008). Nutrient processing rates were most dependent on local environmental conditions, particularly organic matter and sediment grain size. This suggests that site-specific conditions may dictate the impact of floodplain creation on water quality. However, because of the increase in biologically active surface area, the net effect on water quality is likely greater for the two-stage channels.

The glaciated prairie pothole country of the Midwest forms a vital segment of the most important waterfowl breeding habitat in North America. Here are hatched three-quarters of all the ducks raised in the United States. During a recent seven-year period the three-state area of Minnesota and the Dakotas produced an average of 4 to 5 million ducks annually (Janzon, 1947). This wetland region which once comprised 115,000 square miles in five states had shrunk to about 56,000 square miles by 19.56 (Lynch, 1956). To maintain the pre,;ent rate of waterfowl production in the face of continued destruction of habitat through drainage and other land use practices detrimental to breeding ducks will require that remaining wet lands, particularly those in public ownership, be developed as much .as possible toward their maximum potential for waterfowl production. In recent years the U. S. Fish and Wildlife Service has excavated several hundred experimental artificial potholes and level ditches on its refuges in the Dakotas and Minnesota. It was believed that these water areas would increase the number of ducks breeding on the refuge marshes by providing additional territorial sites. Before more funds are invested to expand this work it is important to determine the success of the existing development in meeting this objective. This study, to evaluate the artificial pothole and level ditch development, was initiated. in 1957 by the U.S. Fish and Wildlife Service at Lower Souris National Wildlife Refuge in North Dakota. The project was carried out in collaboration with the Utah Cooperative wildlife Research Unit and the Department of Wildlife Management, Utah State University.

The discharge of point- and non-point source pollutants into surface waters resulting from industrial and/or municipal activities is a major focus of environmental regulation in the United States. As a result, the National Pollutant Discharge Elimination System (NPDES) permit program was established in 1972 in an effort to regulate discharges from industrial or municipal sources, including wastewater treatment plants (WWTP). To further protect Florida water quality, in 1978, State legislation enacted the Grizzle-Figg Act for Tampa Bay, which requires advanced wastewater treatment for any discharge into sensitive water bodies. A common use of wastewater effluent in the Tampa Bay area is for reclaimed water for irrigation. This leads to an estimated 90% reduction of total nitrogen (TN) load to the bay in comparison to direct discharge (TBEP, 2016). One type of wastewater treatment process that has been shown to have low aeration and chemical requirements is simultaneous nitrification denitrification (SND), which can be carried out in an oxidation ditch. SND is a biological process for nitrogen removal where nitrification and denitrification occur at the same time within the same reactor. An oxidation ditch is a race-track type reactor that promotes the occurrence biological conversion of reactive nitrogen to nitrogen gas (N2) and additionally can provide enhanced biological phosphorus removal (EBPR). Many theories exist as to the mechanisms that allow SND to occur, but the literature is inconclusive as to whether the presence of different zones within the floc, within the reactor itself, a combination of the two or unique microorganisms are responsible for SND. Advantages of SND include efficient (80-96%) nitrogen removal, with significant reductions in energy, chemical, equipment and spatial requirements. Specifically, oxygen requirements are reduced and dedicated aerobic/anoxic zones, internal recirculation and supplemental carbon and alkalinity are not required. Despite these advantages, widespread use of SND is limited because of a lack of understanding of SND kinetics as well as interactions between factors affecting SND performance. This research was carried out at the Falkenburg Advanced Wastewater Treatment Plant (AWWTP) in Hillsborough County Florida, which carries out SND, biological and chemical phosphorous removal in an oxidation ditch system. Although this facility continually meets and exceeds its permit requirements, improvements in process control strategies have the potential to improve energy efficiency, as well as decrease chemical use, sludge production, greenhouse gasses (GHG) emissions and costs. Therefore, the overall goal of this research was to investigate mechanisms of nitrogen and phosphorus removal at the Falkenburg AWWTP. These goals were achieved through bench scale SND studies carried out at varying temperatures. Kinetic parameters were determined using a simple kinetic model of nitrification/denitrification. Additionally, carrying out sampling campaigns completed the investigation of the fate of phosphorus in the Falkenburg AWWTP. The results were combined with information on alum dosing and sludge wasting to determine the overall fate of phosphorus in the system and make additional recommendations regarding the addition of alum. To mimic an oxidation ditch at Falkenburg AWWTP, bench scale bioreactor experiments were set up in glass beakers at 22°C and 29.5 C. Influent wastewater and return activated sludge (RAS) for these experiments were collected from the Falkenburg AWWTP. Bioreactors were constantly mixed and aeration was controlled to maintain a target dissolved oxygen (DO) concentration based on measurements of DO at the facility. Three phosphorous sampling campaigns (October, November and December) were also carried out to understand the fate of phosphorous, nitrogen and organic carbon at the facility. In these campaigns, samples were taken at six locations at Falkenburg AWWTP and samples were analyzed for filtered and unfiltered total phosphorus, orthophosphate and polyphosphates, filtered and unfiltered total nitrogen, soluble, total and readily biodegradable COD (rbCOD), volatile acids, cations, anions, alkalinity, total suspended solids (TSS) and volatile suspended solids (VSS). pH and DO were also measured on site. In the nitrification batch reactors, in four hours, 50% of ammonia was successfully removed at a rate of 6.31 mg-N/L/hr indicating that four hours is not sufficient time to achieve complete removal. In the denitrification batch reactors, in six hours, there was successful removal of nitrate and nitrite at a rate of 23.70 mg-NO3-/L/hr and 3.6 mg-NO2-/L/hr. In an SND batch reactor experiments at 22° C, ammonia oxidation successfully occurred in 12 hours but denitrification was inhibited due to insufficient rbCOD in the reactor. In an SND batch reactor at 29.5° C, no accumulation of nitrate or nitrite was observed, indicating successful SND. At a higher temperature, sludge bulking occurred in the reactor resulting in variations in TSS and VSS concentrations. Results from the sampling campaigns at the treatment plant indicate that successful phosphorus removal was achieved. Alum addition varied before each sampling and a relationship between alum addition and sulfate can be made. rbCOD was consumed throughout the treatment process as expected and noticeable results can be noted when rbCOD was low in terms of phosphorus removal. The results of the bench-scale experiments showed that the SND was successfully achieved at the Falkenburg facility and that temperature, DO and rbCOD are all important factors controlling biological nutrient removal at SND facilities. DO is much more difficult to maintain and control at a higher temperature further supporting the idea that stricter operator control is needed in warmer months. Additionally, because SND removal still occurred with poor DO control at 29.5°C, it further supports the idea that SND occurs because of zones within the floc, the reactor or that novel microorganisms exist that allow denitrification to occur above ideal DO concentration and nitrification to occur below ideal concentrations of DO. A variation in rbCOD in the influent wastewater at the treatment plant caused nitrification and denitrification to be inhibited in different trials. With too much rbCOD, nitrification was inhibited and with too little rbCOD, denitrification was inhibited. Additionally, alkalinity consumption was minimal which supports the idea that supplemental alkalinity is not needed in SND processes. The results from the phosphorous sampling campaign show how important influent COD is for successful phosphorus removal in the system. The objectives were achieved and overall, the plant is achieving SND and EBPR and the plant is performing as designed. The addition of alum should continue to be studied to determine a better dose and save the county ratepayers money while still meeting permit regulations. Jar tests should be used to determine the proper dosing that will not hinder the settling properties further in the treatment train. Additionally, alum feed pipe sizes should be investigated at the plant to ensure no clogging occurs with a decrease in alum flow and automated aeration based on ammonia concentrations should be considered to remove the manual operation of aerators.

My diploma thesis is focused on project of water management measure which should intercept torrential water endangering municipality Starovice. In diploma thesis I assess the degree of erosion washes of soil on the solving land. Intensity of soil ablation of affected land is evaluated by Wischmeier-Smith method. Based on the result of long-term soil lost and gathered materials are designed erosion control and water management measures. Graphic part of the thesis contains cartograms with an assessment rate of erosion threat to the investigated area. As part of thesis maps were created using ArcGIS. The essence of the work are drawings situations, longitudinal profiles, sample diagonal incisions of the intercepting ditch were created in Bentley PowerCivil.

The treatment of water for human consumption results in the production of residual waste flows that vary depending on source waters and water treatment technologies. Water treatment plant residual waste is defined as a pollutant that requires treatment either on site or through other means. Due to strict and evolving regulatory requirements, treatment of water treatment plant residual waste several common methods of disposing of water plant residuals exist including discharge to surface waters, discharge to sanitary sewers, and sanitary landfill disposal of dewatered wastes. Although originally discharged to the neighboring City Reservoir, the Carbondale Water Treatment Plant (CWTP) conducted an initial study to determine if plant residual waste could be treated at one of the City’s two wastewater treatment plants. No negative impacts were identified as part of this study and infrastructure was put in place to divert CWTP residual waste from the City Reservoir to the Carbondale Southeast Wastewater Treatment Plant (SEWWTP). This study focused on accessing and quantifying any impacts of Carbondale Water Treatment Plant (CWTP) residual solids sewer discharge on biological treatment processes, effluent water quality, and sludge production at the SEWWTP. The Carbondale SEWWTP treats raw water influent through a number of physical and biological processes including screening, clarification, nitrification/denitrification, and aeration. Of the tests run as part of this study daily samples were collected of SEWWTP influent, mixed liquor, return sludge, and effluent and measured for changes in pH, biochemical oxygen demand (BOD), solids, sludge volume index (SVI), dissolved oxygen (DO), and nitrogen. No significant changes were documented other than percent BOD removal did improve after the introduction of the residuals. Anions were also tested weekly. Samples were collected from the SEWWTP’s oxidation ditch to monitor biological life using biological activity reaction tests (BART) for nitrifying, denitrifying, and heterotrophically active bacteria. BART testing showed no decline in biological activity and increased populations of denitrifying bacteria. Additionally, both metals and acute toxicity of SEWWTP effluent were tested by outside testing facilities to confirm that CWTP residual solids sewer discharge did not interfere with discharge limits established as part of the plant’s permits. No significant changes were observed during testing but plant staff did indicate that more extensive cleaning of the basins was implemented post-introduction. Overall, the case study confirmed that the treatment of CWTP residual solids sewer discharge did not negatively impact treatment processes at the SEWWTP and is sustainable.

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No / Excavation at a cropmark enclosure in the Upper Severn Valley was undertaken to try and obtain material from which to provide relative and absolute dating for the site. Lying within an area rich in Neolithic and Bronze Age archaeology and in close proximity to a proven long barrow, the conventional later prehistoric date postulated for the enclosure was questioned. Excavation proved the site to have been a ditched enclosure with internal bank and a possible gate structure. Post-pits ran inside the bank. Finds were few but radiocarbon dates from the floor of the ditch proved the early Neolithic credentials of the monument which seemed to have continued in use for at least some 500 years.

The state of roadside ditch design and performance has become a topic of concern for the Virginia Department of Transportation. Erosion failures of roadside ditches have occurred frequently enough to indicate that it may be desirable to revise the current design practice. Through the Virginia Transportation Research Council, VDOT has sponsored this research to investigate the state of design practice for these structures and to explore revisions to the design process resulting in a more economical design. To investigate the erosion problems, various VDOT personnel at each of Virginia's nine Construction Districts were interviewed with the intent to gain an understanding of roadside ditch performance in each District. When possible, field visits were made to sites experiencing erosion failure and soil samples were collected for analysis. In addition, experiences and design procedures in neighboring states were reviewed, with the objective of determining if similar problems have been experienced, and if so, how they have been addressed. The survey of other states included nine states, and a site visit to the Mount Airy District of the North Carolina Department of Transportation. A study of the literature relating to the hydraulic performance of unlined and lined ditches was also performed, with the objective of researching available stability criteria used in ditch design and determining if suitable values of Manning's n are being used in Virginia design. The results of this study presented in this thesis represent the best recommended roadside ditch design practice based on current available research. Recommendations include revisions to the current relationship of soil type and maximum allowable velocity, revisions to the application of Manning's n for various lining conditions, and suggestions to improve the overall design and construction process based on surveyed VDOT experience, surrounding states and current research. Future research will be necessary to improve the scientific bases for these recommendations / Master of Science

L'influence des fossés dans les phénomènes de crue, d'érosion hydrique des sols ou de transferts de polluants agricoles est bien connue à l'échelle locale. Cependant, on ne dispose que de peu de connaissances sur la variabilité spatio-temporelle des réseaux de fossés et de l'effet de cette variabilité sur les processus hydrologiques. L'objectif de ce travail de thèse vise donc à quantifier la relation entre l'organisation spatiale et temporelle des réseaux de fossés, éléments de la structure du paysage, et le fonctionnement hydrologique des paysages viticoles méditerranéens.Dans un premier temps, on propose d'analyser comment la densité des réseaux de fossés varie dans les paysages et à quel point elle est conditionnée par le milieu physique. Ensuite, un algorithme de simulation de réseaux est chaîné à un modèle hydrologique afin de quantifier le rôle de la densité des réseaux dans la régulation des écoulements de surface. En lien avec son rôle d'interception du ruissellement, l'effet anti-érosif des réseaux de fossés est alors analysé grâce à l'utilisation d'indicateurs géomorphologiques.Dans un second temps, on s'intéresse à la dynamique spatio-temporelle de la végétation des fossés et à son impact sur les transferts de pesticides. Pour cela, on caractérise puis simule les pratiques d'entretien des fossés et leurs impacts sur la végétation. On montre alors en mobilisant différents indicateurs que les pratiques actuelles ne sont pas optimales d'un point de vue de la rétention des pesticides.Cette thèse, qui s'appuie sur des méthodes de simulation du paysage, montre l'intérêt du chaînage entre modèles de structure et de fonctionnement du paysage. Ce chaînage a permis de quantifier le rôle des réseaux de fossés dans la modulation des processus hydrologiques. / The impact of ditch networks on runoff, soil erosion and pollutant transfer is well known at local scale. However, the spatio-temporal variability of ditch networks and the impact of this variability on hydrological processes has not been quantified. The aim of this thesis is thus to quantify the relation between the spatial configuration of ditch networks and the hydrological functioning of Mediterranean vineyards.First, the variability of ditch network density and the extent to which this density depends on the landscape attributes are analyzed. Then, a network simulator is used with a hydrological model to quantify the impact of ditch network density on runoff. In relation to the role of ditch networks in the interception of runoff on hillslopes, the protection against soil erosion procured by ditch networks is studied thanks to geomorphological indicators.Secondly, the spatio-temporal evolution of vegetation covers in ditch networks and its impact on the transfer of pesticides is analyzed. The ditch management regimes and their impact on ditch vegetation are simulated. Thanks to several indicators, it is shown that current management regimes are not optimal in view of pesticide retention.This thesis shows the interest in using a landscape structure model and a landscape functioning model. This allowed to quantify the impact of ditch networks on hydrological processes.