Nutrients in the sediments of Lake Manitoba’s south basin are resuspended regularly due to its shallow, polymictic nature. In 2009 short sediment core samples were used to determine an internal available nutrient load from sediment of 17,533 tonnes total nitrogen (TN) and 167 tonnes total phosphorous (TP). Water samples were collected at the Whitemud River and Assiniboine River Diversion (ARD) to determine the N and P input to the lake, resulting in an estimate of a total point source input of 3,547 tonnes of TN and 1,130 tonnes of TP. Open water samples were collected to determine a suspended content of 9.2 tonnes of TN /km2 or and 1.7 tonnes of TP/km2. The ARD is the largest contributor of TP to the south basin. The internal sediment pool is a significant source of TN, and when the ARD does not operate, the largest input of TP to the south basin.

Nutrients in the sediments of Lake Manitoba’s south basin are resuspended regularly due to its shallow, polymictic nature. In 2009 short sediment core samples were used to determine an internal available nutrient load from sediment of 17,533 tonnes total nitrogen (TN) and 167 tonnes total phosphorous (TP). Water samples were collected at the Whitemud River and Assiniboine River Diversion (ARD) to determine the N and P input to the lake, resulting in an estimate of a total point source input of 3,547 tonnes of TN and 1,130 tonnes of TP. Open water samples were collected to determine a suspended content of 9.2 tonnes of TN /km2 or and 1.7 tonnes of TP/km2. The ARD is the largest contributor of TP to the south basin. The internal sediment pool is a significant source of TN, and when the ARD does not operate, the largest input of TP to the south basin.

This thesis details the hydrodynamic research conducted at Delta Marsh as part of the Restoring the Tradition marsh rehabilitation project. Research has indicated that the hydraulic and hydrologic controls on the marsh can have considerable impacts on its ecological function, but the impacts of these controls had not previously been studied. Field hydrography and two-dimensional numerical modelling (using MIKE 21) provided insight into many aspects of the physical behaviour of Delta Marsh. Eighty five percent of the inflow to Delta Marsh from Lake Manitoba passes through Clandeboye Channel, and these discharge signals propagate as far west as Cadham Bay. Inflow to the marsh disperses quickly, and accounts for a small fraction of the water that exits the marsh during subsequent outflow. Thus, Portage Diversion water that enters the marsh through the lake can remain there even if there is a net loss in marsh volume over the season. Wind friction across Lake Manitoba has the greatest impact on short-term fluctuations in marsh volume and on the composition of marsh water, followed by the Portage Diversion and the natural inflows to Lake Manitoba. Expansions to flood diversion infrastructure will considerably impact the composition of Delta Marsh waters. Three methods of wetland discharge estimation were developed and tested. The most promising method was the regressed slope Manning method (RSMM), which estimates two-directional channel discharge as a function of the water surface elevations at both ends of a channel. When used in conjunction with the velocity index method, the RSMM can multiply the amount of reliable discharge data collected per research dollar. Thanks to its simple formulation, the RSMM is likely applicable outside of wetland settings, as well. / February 2016