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No description available.

No description available.

Since 1912 concentrations of the major anions and cations (except calcium) in Bear Lake water have shown a steady decrease which has been attributed to a dilution of Bear Lake by Bear River water, Bear Lake having been used as a reservoir for Bear River water since 1918. This study examined the changes which have occurred in Bear Lake water chemistry since 1912 and tested the validity of the dilution theory. Simple water and salinity budgets were determined for the Bear Lake system and used to simulate the effect of Bear River storage patterns since 1918 on the concentrations of sodium, potassium, magnesium, chloride, and sulfate in Bear Lake. Comparison of predicted concentrations with observed concentrations indicates that the dilution theory is a valid one. Field studies were conducted during the spring, summer, and fall of 1971 to describe the distribution of the major ions in Bear Lake with respect to space and time. No significant differences were found between samples collected at different depths and location on the north-south axis of the lake on any one day, but differences were found between sampling days over the course of the study period. A pattern of rapid changes in the concentrations of sodium ions in Bear Lake water was observed in the data from this investigation and noticed also in the data from an investigation conducted in 1959. Adsorption of sodium ions to aragonite crystals precipitating within the lake and/or clay minerals introduced with Bear River inflow is suggested as the cause of these fluctuations in sodium levels.

<p> This research explores the benefits of conjunctively managed surface and groundwater resources in a volcanic aquifer system to reduce stream temperatures while valuing agricultural deliveries. The example problem involves advancing the understanding of flows, stream temperature, and groundwater dynamics in the Shasta Valley of Northern California. Three levels of interaction are explored from field data, to regional simulation, to regional management optimization. Stream temperature processes are explored using Distributed Temperature Sensing (DTS) data from the Shasta River and recalibrating an existing physically-based flow and temperature model of the Shasta River. DTS technology can collect abundant high resolution river temperature data over space and time to improve development and performance of modeled river temperatures. These data also identify and quantify thermal variability of micro-habitat that temperature modeling and standard temperature sampling do not capture. This helps bracket uncertainty of daily temperature variation in reaches, pools, side channels, and from cool or warm surface or subsurface inflows. The application highlights the influence of air temperature on stream temperatures, and indicates that physically-based numerical temperature models, using a heat balance approach as opposed to statistical models, may under-represent this important stream temperature driver. The utility of DTS to improve model performance and detailed evaluation of hydrologic processes is demonstrated. </p><p> Second, development and calibration of a numerical groundwater model of the Pluto's Cave basalt aquifer and Parks Creek valley area in the eastern portion of Shasta Valley helps quantify and organize the current conceptual model of this Cascade fracture flow dominated aquifer. Model development provides insight on system dynamics, helps identify important and influential components of the system, and highlights additional data needs. The objective of this model development is to reasonably represent regional groundwater flow and to explore the connection between Mount Shasta recharge, pumping, and Big Springs flow. The model organizes and incorporates available data from a wide variety of sources and presents approaches to quantify the major flow paths and fluxes. Major water balance components are estimated for 2008-2011. Sensitivity analysis assesses the degree to which uncertainty in boundary flow affects model results, particularly spring flow. </p><p> Finally, this work uses optimization to explore coordinated hourly surface and groundwater operations to benefit Shasta River stream temperatures upstream of its confluence with Parks Creek. The management strategy coordinates reservoir releases and diversions to irrigated pasture adjacent to the river and it supplements river flows with pumped cool groundwater from a nearby well. A basic problem formulation is presented with results, sensitivity analysis, and insights. The problem is also formulated for the Shasta River application. Optimized results for a week in July suggest daily maximum and minimum stream temperatures can be reduced with strategic operation of the water supply portfolio. These temperature benefits nevertheless have significant costs from reduced irrigation diversions. Increased irrigation efficiency would reduce warm tail water discharges to the river instead of reducing diversions. With increased efficiency, diversions increase and shortage costs decrease. Tradeoffs and sensitivity of model inputs are explored and results discussed.</p>

<p> Wastewater generated in the Tucson metropolitan region is conveyed to and treated at the Roger Road Wastewater Reclamation Facility (WRF) and Ina Road WRF. From 2005 to 2012, approximately 15,000 acre-feet per year of effluent was returned to the City of Tucson for additional filtration and reuse in the reclaimed water system. The remaining 48,000+ acre-feet per year of treated effluent was discharged to the Santa Cruz River, where a variable portion of the effluent infiltrates the streambed. The effluent that infiltrates the streambed contributes to recharge credits for participants invested in the Managed Underground Storage Facilities.</p><p> In the effluent-dependent river, physical, chemical, and biological processes work in combination to develop a clogging layer near the streambed surface, which reduces infiltration. Previous studies have shown that large storm events have the ability to scour away the clogging layer and are the most significant processes contributing to establishing infiltration rates. Without the occurrence of large storm events, other variables such as effluent discharge and effluent concentrations affect infiltration to a lesser degree.</p><p> Effluent discharge, biochemical oxygen demand, and total suspended solids are monitored and recorded daily at the outfalls of the WRFs. The parameters were investigated individually and in combination using statistical analyses to determine their correlations with streambed infiltration in the Santa Cruz River. The dry spring-early summer seasons from 2005 to 2012 were analyzed. A water balance was constructed for non-stormflow days during each time period. Evapotranspiration was calculated using riparian vegetation surveys and detailed delineations of aerial photography of the surface water and streamside herbaceous vegetation. Infiltration was derived as the residual of the water balance. </p><p> At the daily time scale, correlations among variables were unobtainable due to the extremely variable characteristics of infiltration. The seasonal time scale analyses demonstrated an inverse relationship between both the effluent concentrations of biochemical oxygen demand and total suspended solids with infiltration and a direct correlation between effluent discharge and infiltration under extreme conditions. Under normal conditions, the distribution of discharge between Roger Road WRF and Ina Road WRF had a critical effect on infiltration as a result of the different deposition and erosive regimes through the Santa Cruz River.</p>

In the environment, oxidized mercury (Hg) can be converted to more toxic chemical species, such as methylmercury (MeHg), as a result of both abiotic and biotic reactions. Hg and MeHg are present in aquatic ecosystems that flow into the Lake St. Francis region of the St. Lawrence River, but their origin is still being debated. A study of mercury and methylmercury contamination in Lake St. Francis in cooperation with the Raisin Region Conservation Authority (RRCA) is ongoing, in collaboration with the Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA) and the Great Lakes Program. A recent report detailed the experimental results for one portion of the area of concern, the Raisin River. The goal of the present project is to update and expand upon the previous work in order to include other existing and new data for this river and several other watercourses feeding Lake St. Francis. Special attention was paid to the MeHg hotspots in an attempt to link methylation and subsequent mobilization to different types of land use and nutrient profiles compiled from new and existing data. It was predicted that water draining off wetlands would have higher MeHg concentrations than water from catchments with other land use profiles. Total and methylmercury were expected to be correlated to the concentrations of nitrogen compounds, sulfate, phosphorus, dissolved inorganic carbon (DIC), and especially dissolved organic carbon (DOC). However, wetlands could not be correlated to MeHg as predicted but the area of crop land was correlated positively with the percentage of THg present as MeHg. Forest and impermeable areas were associated with a decrease in mercury. There was no difference in mercury during wet years compared to dry years when compared on an annual basis, but a significant seasonal difference exists between the two categories. MeHg was positively correlated to DOC, NH3, and BOD. THg was positively correlated to BOD, TSS, Escherichia coli, and fecal coliforms. The percentage of THg present as MeHg (%MeHg) was positively correlated to phosphorus. There were also some statistically significant negative correlations. Forest and impermeable area were negatively correlated with the quantity of MeHg, and impermeable area was negatively correlated with %MeHg. Greater predictor strength and more numerous significant correlations are expected under more thorough sampling and more data.

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Predicting the frequency and aerial extent of flooding in river valleys is essential for infrastructure design, environmental management, and risk assessment. Such flooding occurs when the discharge of water within a river channel exceeds its maximum capacity and the extra water submerges the adjoining floodplain surface. The maximum capacity of a channel is controlled by its geometry, gradient, and frictional resistance. Conventional flood prediction methods rely on assumptions of unchanging flood probabilities and channel capacities. However, changes in climate, land cover, and water management have been shown to systematically shift the magnitude and variability of flood flows in many systems. Additionally, alluvial river channels continually adjust their geometries according to characteristics of flow and sediment regimes. For example, channels can expand their geometry during high-energy flows through erosion, then contract their geometry through sediment deposition during low-energy flows. This means that changes in flow magnitudes, frequencies, or durations can cause changes in a channel’s maximum capacity due to adjustments in river channel geometry. Therefore, future changes in river flow regimes and channel geometry may amplify or attenuate the frequency and magnitude of flood inundation in unexpected ways. The focus of this thesis is the development of a novel simulation model to investigate potential changes in the frequency and aerial extent of floodplain inundation due to systematic changes in peak flows and subsequent adjustments in channel geometry and capacity. The model was run using six hypothetical flow scenarios to explore how changes in the mean and variance of an annual peak flow series influences the frequency and magnitude of floodplain inundation. In order to qualitatively simulate the various mechanisms controlling channel adjustment across a continuum of different river environments, each scenario was run multiple times while gradually varying model parameters controlling the amount of permissible adjustment in channel geometry. Results suggest that systematic shifts in peak flows cannot be translated directly to changes in the frequency or magnitude of floodplain inundation due to the non-linear factors controlling the rate and trajectory of channel adjustment. Insights gained from these results demonstrate the need to account for potential changes in both peak flows and channel capacities in the prediction and mitigation of flood hazards.

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