A hydraulic model was developed to determine differences in the hydraulic characteristics of three different reaches of an urban- and agriculturally-impacted stream in southwest Virginia. The three reaches all had cattle excluded from the channel in 2010. The farthest upstream, Treatment 1, was left to progress without intervention beyond cattle removal while the other two, Treatments 2 and 3, were regraded and stabilized using common stream restoration techniques and a forested riparian was established. The banks of Treatment 2 were regraded to a slope of 3:1 while Treatment 3 was designed with a flat inset floodplain cut into the banks. The model results showed that the self-adjustment in Treatment 1 exhibited inset floodplains with diverse topographical structure including floodplain channels. These adjustments provided higher floodplain volume and mass exchange between the channel and the floodplain when compared with the stable, straight Treatment 2. Comparisons between Treatment 1 and Treatment 3 did not clearly show which treatment was more well connected, with some metrics showing Treatment 1 was more connected while others indicated the opposite. Overall, the findings indicate that stabilization of channelized streams without consideration of the natural planform prolongs adjustment to a channel-floodplain form with more exchange of water, sediment, nutrients and providing refuge for biota. / Master of Science / A water flow model was developed to determine differences in between sections with different management practices an urban- and agriculturally-impacted stream in southwest Virginia. The three reaches all had cattle excluded from the channel in 2010. The farthest upstream, Treatment 1, was left to progress without intervention beyond cattle removal while the other two, Treatments 2 and 3, were stabilized by changing the bank slope and planting trees. The banks of Treatment 2 were regraded to a slope of 3:1 while Treatment 3 was designed with a flat section cut into the banks. The model results showed that the self-adjustment in Treatment 1 created an bench similar to Treatment 3. This section flooded more readily and allowed for higher flow of water between the channel and the floodplain when compared with the stable, straight Treatment 2. Comparisons between Treatment 1 and Treatment 3 did not clearly show which treatment was more well connected, with some metrics showing Treatment 1 was more connected while others indicated the opposite. Overall, the findings indicate that stabilization of channelized streams in their man altered state prolongs adjustment to a more natural form which provides services including flood mitigation, sediment cycling, nutrient cycling and habitat for plants and animals in and along the stream.

Anticipating how stream water quality will respond to change, such as increased pollution or water diversions, requires knowledge of the main mechanisms controlling water and chemical constituent movement and a reasonable representation of those mechanisms. By deriving mathematical models to represent a stream system and collecting supporting field-based measurements, water quality response can be predicted. However, because each stream is unique and the movement of water and constituents is spatially and temporally complex, assessing whether the stream is appropriately represented and whether predictions are trustworthy is still a challenge within the scientific and management communities. Building on decades of stream research, this dissertation provides a step towards better representing some of the complexities found within streams and rivers to better predict water quality responses over long stream distances. First, a method is presented to assess which mechanisms are considered most important in chemical constituent predictions. Next, the number of measurements necessary to represent the general complexities of water, mass, and heat movement in streams was determined. The advancements developed in this dissertation provide a foundation to more efficiently and accurately inform water resource management.