High‐resolution velocity measurements were taken over a series of redds on a gravel‐bed stream using a Pulse Coherent Acoustic Doppler Profiler (PCADP) to quantify the hydrodynamics of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) redds. On redds studied, over 4500 velocity measurements per redd were acquired per day to quantify the flow velocity, flow depth and related fluid mechanics metrics of Reynolds numbers, Froude numbers and turbulent kinetic energy per unit area. Results showed that velocity and Froude numbers varied widely at the redd scale, but consistently showed higher velocities and Froude numbers over the tailspill regions relative to the surrounding study limits. Results of Reynolds numbers calculations showed no apparent correlations to spawning location preference and redd structure. Turbulent kinetic energy per unit area consistently demonstrated a strong correlation with redd locations. The metric maintained low values (i.e. unidirectional flow with little turbulence) where all redds and attempted redds were observed. The study also demonstrates that a number of hydraulic metrics and several spatial scales will likely be necessary to understand any inherent relationship between river hydraulics and redd placement. Copyright © 2010 John Wiley & Sons, Ltd.

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High‐resolution velocity profile measurements were taken over a series of riffles on a gravel‐bed stream using a Pulse Coherent Acoustic Doppler Profiler (PCADP) to quantify the fluid structure of riffles and nests (redds) where brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) spawned. Velocity profiles were obtained on a highly discretized planometric scale ranging between 20 and 40 cm grid spacings, with vertical observations occurring every 1.6 cm. From the velocity profiles, between 15 000 and 38 000 velocity measurements were obtained over each riffle on any given day of measurement. Velocity profiles were converted to streamwise velocity magnitude, flow depth, Reynolds number, Froude number, shear stress, vertical velocity components and turbulent kinetic energy per unit area to evaluate the spatial structure of the riffles and the spatial structure of redds (pits and tailspills) relative to the surrounding riffle structure. Semi‐variograms were employed to evaluate the persistence of the fluid structure based upon the metrics evaluated. Results showed that discrete velocity observations poorly described the spatial structure of the flow system and poorly correlated with redd locations. Reynolds number analysis identified a relatively consistent fluid property for distances typically 2–3 times the longitudinal length of redds. Turbulent kinetic energy per unit area consistently identified common regions on all riffles studied that corresponded with the location selections for redds where flow was identified as essentially uni‐directional. Froude number was found to be insensitive in predicting the fluid spatial structure in wadeable flow depths and relating it to the fluid structure of redds. Results indicated that a series of metrics at varying spatial scales of turbulence may be necessary to understand the spatial complexity of redd selection. Copyright © 2011 John Wiley & Sons, Ltd.

Water management activities are currently predicated on the assumption of a stationary climate, despite the reality of climate change. Hydrologic impacts of climate change for three sub-watersheds north of Toronto for 2041-70 were investigated using the Precipitation-Runoff Modeling System to model six GCM projections from each of RCP 2.6, RCP 4.5, and RCP 8.5. Annual groundwater recharge, evapotranspiration, and the 7Q20 low streamflow statistic were projected to change from 1976-2005 conditions by -2.2% to +20.5%, +0.9% to +14.4%, and -25.5% to +9.8%, respectively. Seasonal shifts included an earlier date of peak streamflow for the majority of simulations and a +14.0% to +103.9% increase in winter recharge. A steady-state MODFLOW model was employed as a preliminary assessment into the effects of climate change on Source Water Protection outputs. The results of this research further the understanding of climate change impacts on human and ecological systems in southern Ontario.

Low impact development (LID) strategies have received attention in recent years as offering a potential way to mitigate the adverse effects of urbanization on hydrologic flow and water quality. The obvious benefits of reduced peak flows and the sizing of storm water ponds can be simulated in models such as USEPA's SWMM; however, the analysis of LID system interaction with the groundwater system is challenging. Addressing questions related to local infiltration capacity, feedback from the groundwater system (i.e. rejected recharge and saturation-excess runoff), and ecological benefits, including the preservation of baseflow and wetland hydroperiod, requires a spatially distributed and integrated analysis of the hydrologic system. The purpose of this chapter is to illustrate the challenges and insights that the authors have encountered while simulating and comparing the effectiveness and ecological benefits of different LID scenarios using an integrated groundwater and surface water model. Additional discussion addresses how this approach can be used to complement storm water modeling and provide for a complete analysis of LID functionality.