Water-Related Theses and Dissertations

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http://hdl.handle.net/1969.1/88066

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Distance weighted method of characteristics solution for solute transport in groundwater
(1986) Prathapar, Sanmugam Ahembaranathan; Reddell, Donald L.; Dornenico, Patrick A.; McFarland, Marshall J.; Newton, H. Joseph; Richardson, Clarence W.
Method of characteristics (MOC) solutions are widely employed in solute transport models of groundwater to estimate tracer concentration. The conventional approach to obtain average tracer concentration for the cell is to arithmetically average the tracer concentration of the moving points within the cell during a particular time step. This requires a large number of moving points and or small cell dimensions to yield satisfactory results. A weighted average using an 'area of influence' for each moving point to estimate the average cell tracer concentration has been proposed and proven effective for steady, uniform flow fields. However, the calculation of an 'area of influence' is difficult for unsteady, non uniform flow fields. Utilization of a 'distance based' weighting function to estimate the average tracer concentration of a cell is proposed in this study. Two inverse and two exponential distance based weighting functions were evaluated. All four weighting functions performed similarly. Hence a quasi error analysis was performed and the inverse weighting function which resulted in a minimal absolute error was chosen for further study. This weighting function performed better than, or as well as the traditional arithmetically averaged routine, depending on the nature of the problem studied. The effect of two forms of moving point introduction, a geometrically uniform pattern and a random pattern on estimation of average tracer concentration of a cell was studied. For uniform, steady flow fields, the geometrically uniform pattern of introducing moving points was found suitable.
Landsat assessment of estuarine water quality with specific reference to coastal land-use
(1978) Hill, John McKinley; Berner, L. D., Jr.; Sweet, M. H.
The highly productive and economically valuable estuaries of the United States are under environmental stress. The effects of human beings in most cases will inevitably increase turbidity, siltation and related pollution in waters in the coastal zone. It is not only aesthetically unpleasing to view waters of low clarity, but an increase in sediment load and resulting turbidity can reduce aquatic productivity, fill dams which cause flooding, and increase the transport mechanism of various pollutants. The detection and monitoring of water color spectra and, where possible, turbidity can be used to find the sources of runoff. The runoff can be used to trace current patterns, distribution of effluents, and related physicobiological relationships. Poor water quality is ultimately the result of land-use problems. Land-use changes must also be closely monitored over time in order to develop management practices that best take water quality into consideration. If Apalachicola Bay, Florida, a relatively pristine and economically valuable estuary, is to be preserved, studied, and managed successfully the relationship of land-use to water quality must be monitored. Florida State University (FSU) has been collecting water quality data, on an almost biweekly basis, since 1972. Landsat was launched in 1972, thereby creating an invaluable and almost irreplaceable data base for correlative water quality/land-useinvestigations. The University of Florida (UF) is attempting to create a hydrologic model of Apalachicola Bay and the East Bay drainage basin. UF is using FSU's water quality data to drive a hydraulic model of Apalachicola Bay. They, however, needed synoptic temporal distributions of water classes and land-use activities in and around the Bay which were provided through the use of Landsat in this research effort.
Quantifying the Effects of the Timing of Water Deficit Stress and Water Deficit Stress Alleviation on Cotton (Gossypium hirsutum L.) Growth and Yield under Rain-Sheltered Controlled Conditions
(2015-08-03) Da Ros Carvalho, Henrique; Fernandez, Carlos J.; Rajan, Nithya; Morgan, Gaylon D.
Water deficit is a major limitation for cotton yield in drought-prone Texas croplands. Where underground or surface water is available and cost affordable, water is applied to crops using a variety of irrigation techniques to mitigate the yield-limiting effects of water deficits. However, dwindling water resources and increased costs can restrict the use of this practice considerably. Most of the work on the effects of timing of water deficits on cotton has focused on yield under variable field growing conditions. A better understanding of the responses of growth and yield would be achieved by quantifying these effects under controlled environmental conditions, where soil variability can be eliminated and water supply accurately controlled. Two studies were conducted in 2014 in the Drought Tolerance Laboratory (Texas AgriLife Research and Extension Center in Corpus Christi, TX) to i) quantify the effects of the timing of water deficits on growth and yield of cotton, and ii) quantify the effects of water deficit stress alleviation at different phenological stages on growth and yield of moderately water-stressed cotton. This facility consists of two joined modified greenhouses where computerized systems control the irrigation regime and collect and process plant water use data automatically. Both studies used cultivar PHY375WRF, which is an early-medium maturity variety with an indeterminate growth habit. Plants were grown in 13.5-L (3.6-gallon) pots filled with fritted clay soil. The experiments were laid out as complete randomized designs with 4 treatments and 4 replications. Data collected shows that water deficits from 1st bloom to mid bloom and from mid bloom to 1st cracked boll had severe effects cotton’s dry biomass production and partitioning, primarily through its decreasing effects on fruit retention, which led to lower economic yield and lower water use efficiency. Supplemental irrigation increased whole-plant transpiration irrespective of phenological timing, but increased total dry biomass of moderately water-stressed cotton only when applied from match head to 1st bloom and from 1st bloom to mid bloom. But these effects did not impact significantly yield or water use efficiency.
Effectiveness of Residential Irrigation System Evaluations in Reducing Water Use in College Station, Texas
(2016-04-29) Nations, Jennifer Douglass; Kaiser, Ronald A; Bame, Sherry; Brumbelow, Kelly; White, Richard
Municipal water use is the fastest growing sector of water use in Texas, representing over three million acre-feet of water demand in 2060 according to the 2012 State Water Plan. Landscapes often receive more water than needed for optimum plant health, due to overwatering from inefficiencies in irrigation system design, poor maintenance and operation practices, excessive run times, and lack of understanding of the irrigation controller. Landscape irrigation evaluations are a water conservation practice intended to point out sources of water waste and provide specific recommendations for improving water use efficiency. This paper presents results of landscape irrigation evaluations conducted in College Station, Texas, between 2010 and 2013. Objectives of this study were to determine change in seasonal irrigation use as a result of receiving an irrigation checkup; determine conformity to a suggested seasonal irrigation budget; and measure changes in amount of excess irrigation over time. Water use was studied for 173 properties in College Station that received an irrigation checkup and exceeded their irrigation budget or had inefficiencies noted during the irrigation checkup, to determine changes in seasonal water use over time and reductions in amount of excess irrigation. Total reduction in seasonal irrigation use was 11.7 million gallons over the four year period of 2011 – 2014, and excess irrigation was reduced by 2 million gallons.
Measuring The Effectiveness of Groundwater Management Policies for the Carrizo-Wilcox Aquifer of Texas
(2014-11-03) Gamache, Kevin Robert; Giardino, John R.; Kaiser, Ronald A; Vitek, John D; Wall, James A
In the United States, more than 80% of the population now lives in urban areas. By 2050, a significant portion of that population will live in megaregions consisting of two or more metropolitan areas linked with interdependent environmental systems, a multimodal transportation infrastructure, and complementary economies. The Texas Triangle Megaregion, one of 8 to 10 such regions in the United States, is spatially delineated by the metropolitan areas of Dallas/Fort Worth, Austin, San Antonio, and Houston, with a total land size of nearly 35,435 square kilometers. Supporting the modern industrial infrastructure of a major metropolitan megaregion has required extensive water-related modifications to the critical zone. These modifications come in the form of an extensive network of dams and reservoirs; a high-density matrix of wells for extracting water, oil, and gas from the critical zone; significant alterations of land cover; and interbasin transfer of ground and surface water. Progressive depletion of critical zone reserves threatens sustainable development in the heavily groundwater-dependent Texas Triangle and requires robust and effective water resource policy for the megaregion to remain economically viable. Facing growth that is expected to double the population of the state to more than 46 million by 2060, Texas has increased its efforts to implement comprehensive water resources planning during the past decade. State policy in Texas dictates that groundwater management is best accomplished through locally elected, locally controlled groundwater conservation districts (GCD). This study examined the effectiveness of GCDs as a water resource management tool in Texas. This research demonstrated no measurable difference in the annual rate of decline in groundwater levels in the Carrizo-Wilcox Aquifer in Texas after establishment of a GCD. The data did not show a correlation between the water allocation method used and the impact on average annual drawdown of the aquifer. The study was not able to demonstrate a relationship between the length of time a GCD has been in existence and the average annual drawdown rates in the aquifer.
Synthesis and analysis of streamflow and salt loads
(Texas A&M University, 1993) Saleh, Ishtiaque
Not available
Analysis of surface-subsurface interaction of streamflow and salt loads
(Texas A&M University, 1992) Sayger, Susan Lee
Not available
A new technique to monitor ground-water quality at municipal solid waste landfills
(Texas A&M University, 1989) Hart, Steven Charles
Not available
Application of a water rights analysis program to reservoir system yield calculations
(Texas A&M University, 1988) Walls, William Brian
Not available
Influence of a river valley constriction on upstream sedimentation
(Texas A&M University, 1988) Kinnebrew, Quin
Not available
Impact of water resource development on the hydrology and sedimentology of the Brazos River system
(Texas A&M University, 1976) Minter, Larry Lane
Not available
Environmentally related water trading, transfers and environmental flows: welfare, water demand and flows
(Texas A&M University, 2008-10-10) Han, Man Seung; McCarl, Bruce A.; Woodward, Richard T.; Boadu, Frederick; Kaiser, Ronald
This dissertation reports on economic studies of Texas Interbasin Water Transfers (IBT) as a way to lessen expected water shortages, Texas minimum freshwater inflows requirements (FWIB) to protect environmental flows and the general policy setup when generators of environmental commodities might be able to sell credits in multiple markets. The Texas-based studies address economic, hydrological and environmental impacts, focusing on welfare gain, water demand, environmental flows and complementary relationship of environmental commodities. Conduct of the two Texas studies required development of a Texas surface water model. The developed model incorporates: (a) uncertain weather patterns and supply of water; (b) river flows in most of the Texas river basins - twenty-one basins excluding only the Rio Grande; (c) demand for water by agricultural, municipal and industrial/ mining water; (d) IBT possibilities; (e) evaporation losses; and (e) return flows across the modeled basins. In studying the interbasin water transfers, three IBT projects where chosen as economically justified relocating water largely for municipal and industrial/mining uses. These IBT projects had the effect of increasing water use and instream flows in the IBT destination basins, but decreasing those in the source basins. In studying the freshwater inflows the study revealed that the suggested inflow constraints were met on average and that the inflow levels for two basins had to be lowered for the constraints to be feasible. This suggests that the contemplated limits are too high and that either multiple basin or flow dependent limits need to be developed. The results also showed that under the average FWIB constraints and IBT implementation, welfare loss from the FWIB constraints was greatly reduced due to the IBT projects which were simultaneously implemented. In the study of multiple environmental commodity markets, the results indicate that generated credits should be sold in multiple markets only when market caps are set up close to socially efficient (so called first-best) caps: this implies that marginal benefit curves are very steep. However, restricting selling into just single market achieved the same net benefits as multiple markets did when market caps were set up at levels less than the first-best caps.
Incorporating salinity considerations in water availability modeling
(Texas A&M University, 2006-08-16) Krishnamurthy, Ganesh; Wurbs, Ralph; Cahill, Anthony; Raghavan, Srinivasan
This research focused on expanding the capabilities of the Water Rights Analysis Package (WRAP) for incorporating salinity considerations in assessments of water availability. A simulation modeling approach was used to address this issue and a generalized simulation model called WRAP-SALT was developed. The Brazos River Basin served as a case study to test the simulation approach adopted by the model. The simulation model adopts a generalized modeling approach applicable to any river basin system. The model tracks salinity throughout a river basin system over different periods of time for alternative scenarios of water use, reservoir system operating policies, and salt control mechanisms. The model was applied to the Brazos River Basin considering different management scenarios and the results obtained were analyzed. Reservoir reliabilities were assessed under user imposed salinity constraints. It was observed that the water supply reliabilities decreased significantly if salinity constraints were considered. Salt control dams proposed by the U.S. Army Corps of Engineers were also incorporated in the simulation of the river basin. It was observed that salinity in the main stem of the Brazos River was significantly reduced. However, no significant improvement was observed in water supply reliabilities.
A statistical model for estimating mean annual and mean monthly flows at ungaged locations
(Texas A&M University, 2004-09-30) Sukheswalla, Zubin Rohinton; Olivera, Francisco; Cahill, Anthony; Srinivasan, Raghavan
Prediction of flow is necessary for planning and management of water resources. The objective of this study is to estimate mean annual flows for the USA and mean monthly flows for the rivers of central Texas based on the precipitation and their watershed characteristics. Flow varies largely with topographic and climatic parameters and hence generalization of runoff models is difficult. This model aims at providing a prediction at ungaged locations with very few parameters that are easily available and measurable. Scatter in predicted data will be seen at the annual and monthly time scale in the range selected for each data. This model will work on annual and monthly means to reduce the scatter and produce better estimates.
Development of an ArcGIS interface and design of a geodatabase for the soil and water assessment tool
(Texas A&M University, 2004-09-30) Valenzuela Zapata, Milver Alfredo; Olivera, Francisco; Srinivasan, Raghavan; Wurbs, Ralph
This project presents the development and design of a comprehensive interface coupled with a geodatabase (ArcGISwat 2003), for the Soil and Water Assessment Tool (SWAT). SWAT is a hydrologically distributed, lumped parameter model that runs on a continuous time step. The quantity and extensive detail of the spatial and hydrologic data, involved in the input and output, both make SWAT highly complex. A new interface, that will manage the input/output (I/O) process, is being developed using the Geodatabase object model and concepts from hydrological data models such as ArcHydro. It also incorporates uncertainty analysis on the process of modeling. This interface aims to further direct communication and integration with other hydrologic models, consequently increasing efficiency and diminishing modeling time. A case study is presented in order to demonstrate a common watershed-modeling task, which utilizes SWAT and ArcGIS-SWAT2003.

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