Groundwater aquifers make up the primary source of drinking water in Florida. It is imperative to protect and maintain water quality to ensure optimal drinking water conditions. Florida is known for being prone to sinkholes due to karst features. One sinkhole event occurred beneath a phosphogypsum stack, and leaked a large amount of radioactive waste in the Floridan aquifer, raising water quality concerns. To study the behavior of contaminant transport, the radioactive waste plume was modeled by coupling hydraulic and chemistry concepts. Adsorption was studied to see if it can serve as a potential remediation solution to the contaminant waste, using available adsorption knowledge and data from previous studies. Results suggest that simulating mineral adsorption helped limit how far the waste stack would travel in the aquifer, however it would still pose risk in water quality, as drinking water wells are situated along the path of the contaminant plume. Implementation of treatment wells and monitoring would ensure drinking water criteria are met. Acknowledging that the Floridan aquifer contains karst features that consist of limestone fractures and the rock matrix, groundwater flow patterns may be influenced over time. For instance, fractures (or conduits) can conduct larger amounts of groundwater at higher conductivities, which could have implications on groundwater/contaminant transport. To model this process, a karst evolution model utilizing hydraulic and chemistry concepts are applied in a basin in Florida. Results indicate the karst model reproduces head profiles and estimates the age of several conduits. A sensitivity analysis was conducted to investigate how karst evolution is influenced by hydraulic and chemistry parameters. Results show that fracture length has more influence on karst evolution, however other physical parameters show some influence as well. A karst conduit network was simulated for the Silver Springs springshed, based on obtained potentiometric head data. Implementing information on aquifer chemistry and fracture geometry resulted in a unique realization of a karst network. During this process, flow rates change direction, inducing backflow, which can have implications on groundwater resources. Overall, an improved understanding of karst processes can aid in better characterizing conduit flow patterns and improve water resources management.

One of the major concerns in the behavior of an earth dam is the change in the exit gradient and the impact on the slope stability under drawdown conditions. Drawdown can cause increased seepage forces on the upstream slope which may result in the movement of soil particles in the flow direction and cause erosion problems. In this research, a numerical approach, based on the finite element method (FEM) is used to analyze the seepage through the dam and its foundation to study exit gradients and slope stability under both steady-state and transient conditions. The results show that a central core is important in reducing the flux through the dam. Constructing a cutoff under the core further increases the efficiency of the core and lowers the phreatic line. However, it is seen that the submerged weight increases when the earth dam with a core or with a complete cutoff which causes higher water flux to flow out of the dam under the drawdown condition. The exit gradient at the upstream slope may reach critical levels and cause failure of the dam due to erosion. Adding an upstream filter is studied as a possible solution to this problem. Two configurations of the filters are modeled and the slope filter configuration performed best in reducing the exit gradient at the upstream face. A low permeability core with a cutoff increases deformation of the soil because of increased saturated areas in the upstream region. The factor of safety of the slope is also reduced because of the increased buoyancy of the soil at the upstream side of the dam. The soil properties of the upstream filter have a significant influence on the slope stability against sliding. An upstream slope filter increases the stability of the slope while a central filter decreases it.

Salt marshes are valued for providing protective and non-protective ecosystem services. Accurate digital elevation models (DEMs) in salt marshes are crucial for modeling storm surges and determining the initial DEM elevations for modelling marsh evolution. Due to high biomass density, lidar DEMs in coastal wetlands are seldom reliable. In an aim to reduce lidar-derived DEM error, several multilinear regression and random forest models were developed and tested to estimate biomass density in the salt marshes near Saint Marks Lighthouse in Crawfordville, Florida. Between summer of 2017 and spring of 2018, two field trips were conducted to acquire true elevation and biomass density measures. Lidar point cloud data were combined with vegetation monitoring imagery acquired from Sentinel-2 and Landsat Thematic Mapper (LTM) satellites, and 64 field biomass density samples were used as target variables for developing the models. Biomass density classes were assigned to each biomass sample using a quartile approach. Moreover, 346 in-situ elevation measures were used to calculate the lidar DEM errors. The best model was then used to estimate biomass densities at all 346 locations. Finally, an adjusted DEM was produced by deducting the quartile-based adjustment values from the original lidar DEM. A random forest regression model achieved the highest pseudo R2 value of 0.94 for predicting biomass density in g/m2. The adjusted DEM based on the estimated biomass densities reduced the root mean squared error of the original DEM from 0.38 m to 0.18 m while decreasing the raw mean error from 0.33 m to 0.14 m, improving both measures by 54% and 58%, respectively.

Hydraulic losses in sewer pipes are caused by wall roughness, blockages and in-pipe sedimentation. Hydraulic resistance is a key parameter that is used to account for the hydraulic energy losses and predict the sewer system propensity to flood. Unfortunately, there are no objective methods to measure the hydraulic resistance in live sewers. A common method to estimate the hydraulic resistance of a sewer is to analyse collected CCTV images and then to compare them against a number of suggested hydraulic roughness values published in the Sewer Rehabilitation Manual. This thesis reports on the development of a novel, non-invasive acoustic method and instrumentation to measure the hydraulic roughness in partially filled pipes under various structural and operational conditions objectively. This research presents systematic laboratory and field studies of the hydraulic and surface water wave characteristics, of shallow water flows in a sewer pipes with the presence of local and distributed roughness, in order to relate them to some fundamental properties of the acoustic field measured in the vicinity of the flow surface. The results of this thesis indicate that for the local roughness the energy content of the reflected acoustic signal is an indicator of the pipe head loss and hydraulic roughness. In the case of the distributed roughness, the variation in the temporal and frequency characteristics of the propagated sound wave can be related empirically to the mean flow depth, mean velocity, wave standard deviation and hydraulic roughness.

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In the last few decades, miniaturization has been in increasing demand in many applications. The miniature actuators should comprise high power-weight ratio while having a fast dynamic response, and high efficiency. In this thesis several approaches have been studied to develop a low pressure water hydraulic system driving a miniature rotary joint as the end-effecter. While the system was expected to have a cross sectional diameter of 15 mm, two prototypes were manufactured having cross sections of 12.5 mm X 13 mm (18 mm dia.) and 16 mm X 18 mm (24 mm dia.). The system involves a novel closed-circuit water hydraulic system in which a controlled volume of water supplied by a motor-cylinder pump drives the rotary joint cylinders (4 mm bore). The linear motion of these cylinders is converted to a rotational motion through a sliders-pulley mechanism. The rotation of an arm attached to this pulley is measured by a magnetic rotary encoder. The dynamic behaviour of the system was studied and the most important parameters have been modelled. This model has been utilized in the design of a model based feedforward (FFWD) controller which was added to a PID controller to enhance the position control of the rotary arm. Numerous experiments were conducted with the horizontal rotation of the rotary arm. The maximum error ( emax) recorded for a mixed input (a combination of rising and falling cycloidals of 120° and 60° with pause periods of 1 and 0.5 s) with a PID controller was 8.3° while with the addition of the FFWD term this dropped to 6.2°. The maximum root mean square error (RMSE) for the same trajectory has been 1.7° and 0.9° for PID and FFWD+PID controllers respectively. The steady state error (SSE) which was measured during a eycloidal input of 120° was recorded to be in the range of ±0.2° for both of the controllers. The robustness of the controllers was evaluated by adding a mass of 8.5 g to the end of the rotary arm which produced an un-modelled extra large inertia to the system dynamic when the arm rotating horizontally. Robustness of both controllers was demonstrated as the change in the main numerical performance indicators (RMSE, ernax, and SSE) were not remarkable. Another set of experiments performed with the rotary joint positioned vertically introduced with an un-modelled changing force. The numerical performance indicators were almost unchanged again. A comparison between the results of this thesis with the ones from the previous work in our laboratory by R. Sindrey indicates a significant improvement. / Thesis / Master of Applied Science (MASc)

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Servovalves are a key factor in determining the performance characteristics of an electrohydraulic position servo. This paper examines the interrelationships between servovalve parameters and system requirements. A brief description of the configuration and operation of a typical servovalve is presented. Key servovalve parameters are identified, defined, and discussed. System performance considerations are identified, and the interrelationships between system requirements and servovalve parameters are examined. Examples of servovalve parameters for missile, aircraft and industrial systems are given to illustrate the effect of system requirements on a servovalve. Finally, general guide-lines for selecting and specifying servovalve parameters are given.