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Full-Text Articles in Earth Sciences
Groundwater Flow And Salt Marsh Migration: The Forest/Marsh Boundary, Camille Rossiello
Groundwater Flow And Salt Marsh Migration: The Forest/Marsh Boundary, Camille Rossiello
Theses and Dissertations
Salt marshes migrate landward in response to sea level rise, but the rate of this migration is not constant and can be influenced by pulse disturbances. Long term observations at Sapelo Island, Georgia, show that salt marsh migration has occurred during droughts, but the mechanism for this migration is unclear. Drought is thought to influence salt marsh migration by reducing fresh groundwater discharge from the upland. Rising sea level also encroaches on the upland, which could cause movement of the freshwater lens inland. A two-dimensional numerical model was built to simulate groundwater flow and solute transport based on the Marsh …
Water Chemistry And Lake Dynamics Of Laguna Bacalar, Quintana Roo, Mexico, Ryan Matzuk
Water Chemistry And Lake Dynamics Of Laguna Bacalar, Quintana Roo, Mexico, Ryan Matzuk
Theses and Dissertations
Laguna Bacalar in the Quintana Roo region is the second largest lake in Mexico and contains freshwater derived solely from groundwater. Local geology on the Yucatan Peninsula is karstic and the southern shoreline of Laguna Bacalar is spotted with a handful of cenotes that contribute substantial amounts of inflowing groundwater to the lake. This is shown by sonde profile data taken in one of the largest cenotes in the area. Outflow is dominated by a surface water outlet in the southern portion of the lake and an unknown amount of outflowing groundwater. During January of 2017 through 2019, UWM researchers …
Integrating Gis And Hydrology For Flood Risk Analysis, Anas B. Rabie
Integrating Gis And Hydrology For Flood Risk Analysis, Anas B. Rabie
Theses and Dissertations
Spatial analysis using GIS was evaluated for its ability to predict the potential hazard of a flood event in the Illinois River region in the State of Illinois. The data employed in the analysis are available to the public from trusted organizations such as Illinois State Geological Survey (ISGS), and the US Geological Survey (USGS). The purposes of this study are to 1) examine the applicability of GIS spatial analysis to determine flood inundation risk, and 2) to determine how to do so with the least amount of data possible, while still producing an accurate flood inundation risk map. This …
Analysis Of Electromagnetic And Seismic Geophysical Methods For Investigating Shallow Sub-Surface Hydrogeology, Eric M. Parks
Analysis Of Electromagnetic And Seismic Geophysical Methods For Investigating Shallow Sub-Surface Hydrogeology, Eric M. Parks
Theses and Dissertations
An integrated electromagnetic (EM) and seismic geophysical study was performed to evaluate non-invasive approaches to estimate depth to shallow groundwater in arid environments with elevated soil salinity where the installation of piezometers would be impractical or prohibited. Both methods were tested in two study areas (semi-arid and arid respectively), one in Palmyra, Utah, USA near the shore of Utah Lake where groundwater is shallow and unconfined in relatively homogeneous lacustrine sediments. The other area is Carson Slough, Nevada, USA near Ash Meadows National Wildlife Refuge in Amargosa Valley. The area is underlain by valley fill, with generally variable shallow depths …
The Rate And Timing Of Direct Mountain Front Recharge In An Arid Environment, Silver Island Mountains, Utah, Gregory T. Carling
The Rate And Timing Of Direct Mountain Front Recharge In An Arid Environment, Silver Island Mountains, Utah, Gregory T. Carling
Theses and Dissertations
Direct mountain front recharge (MFR), water table recharge at the base of the mountain front, was evaluated on the arid (<250 mm/yr precipitation) Silver Island Mountains by comparing mountain precipitation to groundwater response. Direct MFR contributions were assessed on two catchments, one bedrock (i.e., mountain block) dominated and the other alluvial fan (i.e., mountain front) dominated. Catchment precipitation and shallow groundwater levels at each catchment outlet were measured for a 24 month period beginning October 2005. This time period captured one complete hydrologic cycle (December 2005-February 2007) for which annual and seasonal direct MFR rates were calculated. Annual direct MFR was calculated using a modified version of the water table fluctuation (WTF) method as 0.015-0.016% of precipitation on both catchments, with seasonal variations of 0% in summer up to 0.023% in winter, spring and fall. Seasonal direct MFR contributions are similar on the bedrock and the alluvial fan dominated catchments, with a notable exception during fall 2006 when direct MFR was twice as effective on the bedrock dominated system than on the alluvial fan dominated system (0.022% and 0.011% of precipitation, respectively). Darcy's law calculations show similarly low annual direct MFR contributions (0.013-0.032% of precipitation) as those calculated by the WTF method. Calculated direct MFR is 10% or less than typical calculated combined MFR (near surface recharge and deep underflow from the mountain block) for similar terrains and climates, and is only 3.5% of the combined MFR for the Silver Island Mountains as calculated by the Maxey-Eakin model. However, based on total recharge to the adjacent playa, it is apparent that the Maxey-Eakin model overestimates combined MFR, and the small calculated direct MFR is at least 50% of combined MFR. Despite some uncertainty in the numerical results, several patterns are evident in the data. The data show that direct MFR occurs in response to small rainfall events throughout much of the year, and that snowmelt is not necessary to produce direct MFR. The data also show that direct MFR responds more quickly and flushes through the system faster on the alluvial fan catchment than on the bedrock catchment.