This thesis examines both surface water and shallow groundwater connections in boreal watersheds at two study sites in the Athabasca Oil Sands Region using conventional hydrological techniques as well as stable water isotope techniques. Increased emissions due to oil sands development are expected to contribute significantly to acidifying airborne emissions. Specifically, nitrogen is forecasted to be deposited on the surrounding area within approximately 100 km of operations. The purpose of the research is to provide background information for predicting how individual terrain units such as fens, bogs, and uplands will respond to increased nitrogen loads, and to assess whether or not these units will act as sources or sinks of nitrogen under higher nitrogen deposition. Two study sites situated within 100 km of Fort McMurray, Alberta were instrumented with a total of 30 nested piezometers, 26 water table wells, 4 micro-meteorological stations, and two gauging stations (weirs) at outflow points. Monitoring occurred during the open water season of 2011 and 2012. This study estimates evaporation through a simplified energy balance, documents hydraulic conductivity of shallow aquifers, utilizes stable isotopes of water to assist in mapping seasonal flow patterns, and calculates a vertical water balance for the sites. Bogs and fens were hydrologically connected, as bogs fed fens laterally at shallow depths within the acrotelm during wet years. Upland terrain units were found to have more variable connections. In spring, upland runoff recharged the wetlands at both sites. At JPH groundwater flowed towards the fen, whereas in ML limited connections were observed between the uplands and the fen. Also, no connections were seen to indicate that the wetlands recharged the uplands. A conceptual model is developed that emphasizes the role of connectivity in the boreal landscape. The main implication for nitrogen cycling is that it is difficult to quantify one landscape as a source or sink for additional nitrogen as its role may vary depending on seasonality and temporal scales. Further work is needed to identify if nitrogen loadings will have adverse affects on geochemistry of water at the sites. / Graduate / 0366 / amyvallarino@gmail.com

Wetlands are an essential part of the water management system in South Florida, providing many ecosystem services. However, the hydrologic connections of many wetlands, including Loxahatchee Slough in Florida, are poorly understood. Loxahatchee Slough is Palm Beach County’s most diverse natural area and a site of ongoing restoration. The primary objective of this research was to characterize the spatial and temporal variability of surface-groundwater exchange at Loxahatchee Slough. The Magnitude of groundwater seepage to the canal varied spatially. Little seasonal variability in exchange was identified in this study. Canal stage had a strong relationship with groundwater levels and slough stage indicating its important influence. This study provides more insight into the heterogeneous nature of wetland-canal exchange and the need for site-specific evaluation at wetlands for successful management. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Nov. 30, 2009). Includes bibliographical references (p. [42]-45).

Wetland ecological function greatly depends on the wetland hydrology. As a result, correctly estimating the wetland water budget, is essential to the success of created wetlands. A wetland water budget model, Wetbud, was developed by collaborators from Virginia Tech, Old Dominion University, and the Technical University of Crete for estimating wetland water budgets to assist wetland design in the Virginia Piedmont. The Wetbud model has basic and advanced modules. The basic module uses level pool routing to compute average monthly water levels. Based on the groundwater model MODFLOW, the advanced module estimates groundwater interactions and vegetative resistance to surface flows on a daily timestep. The overall goal of this research was to assess Wetbud as an uncalibrated design model for mitigation wetland water budget estimation in the Virginia Piedmont. Specific objectives were to compare predictions using the basic and advanced modules and to compare the Thornthwaite and the FAO-56 Penman-Monteith potential evapotranspiration estimation methods for the design of created wetlands. The Wetbud model was tested using data from two existing mitigation wetlands. Both modules produced reasonable results; however, the basic module did not accurately predict drawdown occurring during dry periods. Results showed that the Wetbud advanced module produced more accurate and detailed results when compared to the basic module: Nash-Sutcliffe model efficiency ratings for the advanced module ranged from to 0.44 to 0.63. Potential evapotranspiration estimates by the FAO-56 Penman Monteith method were more accurate than those from the Thornthwaite method in nearly every model scenario / Master of Science

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 40-48). Also available on the World Wide Web.

>Magister Scientiae - MSc / The Kars has a well-defined channel along the 62 km stretch from its sources in the Bredasdorp Mountains. After entering the Agulhas plain which has a very low gradient, this river changes into a triangular shaped wetland. This wetland is 7 km in length with no defined channel running through it. The wetland then discharges into another 7 km long channel that joins the Heuningnes River with its mouth at the Indian Ocean. The presence of the wetland causes frequent flooding which affects cultivated lands and a major highway linking towns on the coastal Cape Agulhas area with the rest of the country. Before this study, there was no monitoring of flows along the Kars River including water levels within the wetland. Consequently, the conditions leading to flooding of the wetlands were unknown. This study is aimed at understanding how the combination of local rainfall, Kars River inflow into the wetland, soil characteristics, and the morphology of the wetland influence flooding/inundation. The study monitored river inflows into and outflows from the wetland. A soil survey was conducted within the wetland using the augering method and an infiltrometer to determine soil type and infiltration rates. This was done to assess the hydrological characteristics of the wetland. Using the collected climate data and river flow data, a conceptual model was developed for predicting downstream outflows and possible flood events on a daily timescale. The results indicated that the Kars wetland comprises soil with high silt and clay content, and low infiltration capacity. The wetland causes flood attenuation and diffuse surface flows. Low infiltration rates result in ponding of local rainfall which can contribute to flooding.

A hydrological modelling effort using MODFLOW was undertaken in order to determine the relative importance of some of the factors influencing hydraulic gradient reversals in peatlands. Model domains were of two types, large raised bog type (LRBT) and kettle bog type (KBT), and were made to undergo various levels of meteorological forcing (water deficit). Substrate, too, was varied in order to determine its importance on reversals. Domain-wide reversals were successfully simulated in LRBT systems, but not in KBT systems. Although simulated flow patterns matched field-observed patterns, both pre- and post-drought, simulated reversals occurred more quickly than in the field. This may be due to insufficiently distributed parameters, such as hydraulic conductivity. Reversals were easily terminated by simulating non-drought conditions. In the LRBT system, reversal duration decreased, and time-to-reversal increased, with a decrease in drought severity. Increasing drought severity in KBT systems had the opposite effect on the duration of semi-reversed flow patterns, suggesting a possibly different/additional mechanism for flow reversals in KBT systems. Hydraulic conductivity had an appreciable effect on flow reversal evolution, though neither changing porosity, nor differences in catotelm layering had a great effect.

The Mkuze Wetland System, situated in northern KwaZulu-Natal, is South Africa’s largest freshwater wetland area. The system plays a vital role in the functioning of the local landscape and has been identified as an important site for the retention of a number of solutes. The mechanisms through which this retention occurs were investigated through analysis of sediment, groundwater and porewater samples collected from the lower floodplain. Sample analysis was achieved through the use of several techniques, including Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), X-ray Diffraction (XRD), X-ray Fluorescence (XRF), electron microscopy and sequential extraction. / Thesis (Ph.D)-University of KwaZulu-Natal, Westville, 2008.

Thesis (Ph.D.)--University of Waikato, 2006. / Includes bibliographical references (p. [75]-85) Also available via the World Wide Web.

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