This thesis formulates a conceptual framework developed from field observations that describes the influence of surface depressions or potholes on runoff generation in the prairie pothole region of the North American prairies. The fill-and-spill of potholes results in intermittent surface water connectivity between potholes within the basin. The extent of connectivity between potholes is dependent on antecedent water levels. Dynamic connectivity between potholes results in dynamic contributing areas for runoff. The concept of connectivity is manifested in the conceptual curves presented in this thesis. These conceptual curves model the response of runoff events for landscape types found in the prairie pothole region, and capture the influence of the spatial distribution and extent of surface storage on contributing area. The conceptual curves differ due to variations in the spatial distribution and extent of surface storage volume.<p> An algorithm based on the conceptual framework proposed is presented. The algorithm, which uses the the D-8 drainage direction method, automates a methodology for identifying and quantifying runoff contributing area. The algorithm is applied in prairie pothole basins both to demonstrate its efficacy and to test the potential for using conceptual curves to describe the relationship between decreasing potential surface storage in the landscape and contributing area. The algorithm was applied to two digital elevation models (DEM) representative of the prairie pothole region. The first DEM was created using LiDAR elevation points at a 1 m resolution for the St. Denis watershed, and the second was created from orthophotos for the Smith Creek watershed at a 25 m resolution.<p> Fieldwork in the St. Denis watershed was carried out to both provide a basis for the conceptual framework proposed and to validate the results of the algorithm. The fieldwork involved gathering snow survey data, identifying and describing surface water conditions during a snow melt runoff event in 2006, and measuring pond levels from 2004 2007.<p> Results indicate that the proposed conceptual curves represent the non-linear relationship between potential surface storage and contributing area generated by the algorithm in the test basins. To test whether the underlying concepts of the algorithm were valid, the algorithm was used to model pond level depths measured in the St. Denis drainage basin after spring runoff in 2006 and 2007. An r2 value over 0.9 was calculated for the relationship between measured and modeled pond levels in both years. Based on this work, it is clear that any hydrologic study or model applied in the prairie pothole region should consider the effect of dynamic contributing areas on runoff generation.

This thesis formulates a conceptual framework developed from field observations that describes the influence of surface depressions or potholes on runoff generation in the prairie pothole region of the North American prairies. The fill-and-spill of potholes results in intermittent surface water connectivity between potholes within the basin. The extent of connectivity between potholes is dependent on antecedent water levels. Dynamic connectivity between potholes results in dynamic contributing areas for runoff. The concept of connectivity is manifested in the conceptual curves presented in this thesis. These conceptual curves model the response of runoff events for landscape types found in the prairie pothole region, and capture the influence of the spatial distribution and extent of surface storage on contributing area. The conceptual curves differ due to variations in the spatial distribution and extent of surface storage volume.<p> An algorithm based on the conceptual framework proposed is presented. The algorithm, which uses the the D-8 drainage direction method, automates a methodology for identifying and quantifying runoff contributing area. The algorithm is applied in prairie pothole basins both to demonstrate its efficacy and to test the potential for using conceptual curves to describe the relationship between decreasing potential surface storage in the landscape and contributing area. The algorithm was applied to two digital elevation models (DEM) representative of the prairie pothole region. The first DEM was created using LiDAR elevation points at a 1 m resolution for the St. Denis watershed, and the second was created from orthophotos for the Smith Creek watershed at a 25 m resolution.<p> Fieldwork in the St. Denis watershed was carried out to both provide a basis for the conceptual framework proposed and to validate the results of the algorithm. The fieldwork involved gathering snow survey data, identifying and describing surface water conditions during a snow melt runoff event in 2006, and measuring pond levels from 2004 2007.<p> Results indicate that the proposed conceptual curves represent the non-linear relationship between potential surface storage and contributing area generated by the algorithm in the test basins. To test whether the underlying concepts of the algorithm were valid, the algorithm was used to model pond level depths measured in the St. Denis drainage basin after spring runoff in 2006 and 2007. An r2 value over 0.9 was calculated for the relationship between measured and modeled pond levels in both years. Based on this work, it is clear that any hydrologic study or model applied in the prairie pothole region should consider the effect of dynamic contributing areas on runoff generation.

Ontario’s rock barrens landscape consists of exposed bedrock ridges which host a mosaic of thin lichen- and moss- covered soil patches, forested valleys, beaver ponds, and depressional wetlands. Peat-filled ephemeral wetlands within bedrock depressions act as gatekeepers to hydrological connectivity between their small headwater catchments and the rest of the landscape downstream through strong fill-and-spill dynamics. We developed a water balance model, RHO, with inputs of precipitation and potential evapotranspiration (PET) to better understand the factors impacting water table (WT) and storage dynamics and in turn the hydrological connectivity of ephemeral wetlands. Field surveys were conducted at six wetlands to obtain and determine the variability in measurable site characteristics, in particular the wetland depression morphometry, to parameterize RHO. Three sites were used in a calibration and validation procedure where modelled WTs were compared to measured WT data from the snow-free seasons for each site to determine the best parameter values. We show that RHO is capable of predicting WT dynamics with inputs of precipitation and PET, when parameterized for specific sites. Wildfire disturbance is known to increase the run-off from hillslopes and remove surface organic soils through combustion. To predict the impacts of wildfire disturbance on ephemeral wetland hydrological connectivity, a generic model wetland depression was parameterized in RHO and used to predict the changes in hydrological connectivity under various wildfire scenarios and test the sensitivity of modelled connectedness to impacted parameters. Modelled results show that connectivity increases under all scenarios tested, and that changes to connectivity are primarily due to increases in run-in. Water balance models, like RHO, can be used to better understand the hydrological connectivity of wetlands in a rock barrens landscape. These models are useful in predicting impacts on the hydrological connectivity, and hydrological ecosystem services, from disturbances such as wildfire and can inform future field research experimental designs. / Thesis / Master of Science (MSc) / Rock barrens landscapes provide several important ecosystem services, which are influenced by hydrological flow paths and water storage on the landscape. Central to these hydrological dynamics is the storage and discharge of water in small wetlands which form in bedrock depressions. Here we develop a simple hydrological model to simulate the water storage and discharge of rock barrens wetlands. We then use this model to explore how wildfire disturbance is likely to change the supply of water to the rest of the landscape by simulating several different scenarios and testing which changes in the model have the largest impact on the water supply. We show that wetlands discharge more water after wildfire disturbance, mainly because of increases in run-off from areas upstream of the impacted wetlands. This modelling approach helps us better understand how wildfire is likely to impact the ecosystem services of a rock barrens landscapes.

The depositional styles of sediment gravity currents depend, in part, on the relationship of flow magnitude to the scale of topographically controlled containment and range from unconfined lobes to fully contained deposits. Determining the degree of containment is important for understanding depositional processes, land to ocean sediment transfer and subsurface reservoir characterization/prediction. Depositional models of the fully contained (commonly referred to as 'ponded') end member have been developed (e.g. fill-and-spill model). However, fully contained deposits represent only a portion of deepwater deposits and little work has been done identifying and examining the degree of containment of the more complex, partially contained deposits in outcrop. Here, I document the sedimentological facies and stratigraphic architecture of the Zorrillo Unit, a partially contained system exposed at Cerro Solitario within the Upper Cretaceous Tres Pasos Formation of the Magallanes Basin. The evolution of partial containment at this outcrop is expressed as: 1) bypass in the proximal zone and flow stripping in the distal zone, 2) backstepping and blanketing of the outcrop, followed by 3) renewed bypass. The partially contained system at Cerro Solitario deviates from the widely used fill-and-spill model due to subtle relief. This record of infilling provides insight into the overall evolution of the depositional system. Within the Magallanes Basin, the partially contained and linked depocenters along the Chingue Clinoform represent the dying breaths of the Cerro Toro axial conglomerate channel system as the canyon-fed point source collapsed and choked off the sediment routing system out to the distal basin. / Master of Science