Browsing by Subject "Ogallala Aquifer"
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Item Agroecology of three integrated crop-livestock systems in the Texas High Plains(2012-05) Zilverberg, Cody; Allen, Vivien G.; Johnson, Phillip N.; Galyean, Michael L.; Moore-Kucera, Jennifer; Villalobos, Carlos; Kellison, RickTechnological advances have enabled agriculture to feed and clothe a growing global population with great success. It is now imperative that we remain productive while halting the natural resource degradation that often accompanies high productivity. In the semi-arid Texas High Plains, sustainability of current agricultural practices is threatened by depletion of the Ogallala aquifer and soil erosion. Perennial grasses, the region’s historic vegetation, can build soil rather than lose it and require little or no supplemental irrigation. We designed and tested three agroecosystems that integrated crop and livestock production using a base of perennial forages. All systems were designed to decrease water withdrawals from the Ogallala aquifer relative to conventional irrigated agriculture. The experiment covered a total of 42 ha in a randomized block design with three blocks. The non-irrigated system, DRY (evaluated from 2004 to 2008), included a paddock of native perennial grasses and a rotation of cotton (Cynodon dactylon [L.] Pers.) and foxtail millet (Setaria italica [L.] P. Beauv.). The buffer-irrigated system, LOW (evaluated from 2009 to 2011), was the same as DRY except that LOW added an irrigated paddock of ‘WW-B. Dahl’ old world bluestem (Bothriochloa bladhii [Retz] S.T. Blake; hereafter bluestem), which was harvested for grass seed as well as grazed. The limit-irrigated system, MED (evaluated from 2007 to 2011), included two irrigated paddocks of bermudagrass that were grazed and harvested for hay, and one paddock of bluestem that was grazed and harvested for grass seed. Angus beef stocker steers (Bos taurus L.; initial BW: 245 kg) sequence-grazed each system. We evaluated these systems with a variety of criteria, including forage and animal production, water use, crop yields and quality, forage quality, soil C fractions, soil penetration resistance, forage species stability, economic performance, fossil fuel energy use, and C emissions associated with fossil fuel use. We found that each system had strengths and weaknesses. Annual irrigation water use by each system was: DRY, 0 mm; LOW, 44 mm; and MED, 229 mm. The MED system was the most productive, yielding 446 kg steer live weight gain ha-1, compared with 107 for LOW and 57 for DRY. Bermudagrass yielded the most animal unit grazing days ha-1 (644; bluestem: 246; native grasses: 90; annuals: 41) of any forage and was the highest quality forage with the exception of the annual, foxtail millet. Bermudagrass also had the highest soil concentration of particulate organic matter C (3.1 g kg-1 soil in top 5 cm; native grass: 2.5; bluestem: 2.1), an indicator of higher potential nutrient mineralization and soil C accumulation. The annual fields had the lowest levels (1.3 g kg-1 soil in top 5 cm); however, the MED system was the worst economic performer and emitted the most C (774 kg C ha-1; LOW: 226; DRY: 205) as a consequence of fossil fuel use. In contrast, DRY produced the least amount of grazing (72 animal unit grazing days ha-1; LOW: 76; MED: 434), but was the most profitable and used no irrigation water. Although productivity of DRY and LOW were less than MED, LOW and MED beef carcasses were of equivalent quality (68% USDA Choice; DRY was not evaluated) and cotton lint from DRY and LOW received price premiums in all years (mean $0.024 and 0.106 kg-1, respectively). The lessons learned from this experiment should be used to design future agroecosystems that conserve soil and water while producing agricultural goods. Relative to annual and perennial non-irrigated paddocks, applying irrigation and N to introduced forages increased productivity and accelerated soil C sequestration, but the additional inputs were not justified economically. It may be more profitable to integrate, at the farm or landscape scale, large areas of non-irrigated native grasses in combination with smaller areas of intensively farmed, high-value crops that receive irrigation and fertilizer. Ley farming, which includes long rotations of perennial grass with annual crops, is one option that may hold promise for the future.Item Analysis of percipitation and saturated thickness of the Texas Ogallala Aquifer(2010-08) Warren, Ada R.; Mulligan, Kevin; Lee, Jeffrey A.; Johnson, JeffThe Ogallala Aquifer is an important source of groundwater for agricultural and municipal supplies on the Texas High Plains. It is widely recognized that water levels in the aquifer are declining at an average rate of about one foot per year. Declining aquifer water levels are a result of water extraction occurring faster than aquifer recharge. Although the water levels of the aquifer are declining, the rate of decline fluctuates year-to-year and it seems reasonable to assume that variations in annual or seasonal precipitation contribute to the variability in the rate of decline. The precipitation rates affect the amount of water extracted by producers for irrigating crops. To address this problem, the objective of this thesis was to determine if precipitation has an effect on the rate of water extraction from the Ogallala Aquifer. This study compares the annual change in saturated thickness with precipitation data for the study area to determine the relationship between aquifer drawdown and precipitation. Well data for the Ogallala Aquifer were acquired for 1990 to 2008 for 10 counties on the Southern High Plains. The well data were used to calculate saturated thickness and rate of decline for each year. The saturated thickness was compared with annual and seasonal precipitation totals for each year. The results from this study found that annual precipitation amount has a statistically significant effect on the rate of decline of saturated thickness of the Ogallala Aquifer in Texas. Furthermore, seasonal precipitation will have a greater effect on the rate of decline of saturated thickness than annual precipitation.Item Design and control of an integrated wind-water desalination system for an inland municipality(Texas Tech University, 2008-08) Noll, Dennis D.; Ewing, Bradley T.; Song, Lianfa; Swift, Andrew H. P.; Chapman, Jamie C.Current water pricing standards do not take economic responsibility for dwindling potable water aquifer resources. By only incorporating financial, but not true economic costs of these scarce resources, serious depletion of these often slow-recharging groundwater resources has occurred in many areas in the United States. Aquifer depletion for some areas looms on a 50-year or closer horizon, and many municipalities in the Southwest and elsewhere face potential distress due to lack of sustainable fresh water availability. In order for these cities to remain economically and physically viable, alternative water resources must be found. An affected West Texas inland municipality will become the subject of research to evaluate the technology and economics of a full-scale, integrated, wind-powered reverse osmosis water purification system. The integrated system will be applied to produce potable water from a brackish aquifer using renewable energy to reduce the energy costs of the system. An adaptive and intelligent control algorithm will control the integrated wind-water system. The algorithm will process streaming real-time water use and electrical demand data in combination with wind speed measurements in order to determine the best use of the energy produced by a turbine array: either for water purification or for displacing conventional power on other municipal loads. The end product of this system is a water purification process that will utilize a brackish water aquifer for all of the city‘s potable water needs, and wind energy for all associated pumping, reverse osmosis, distribution and other electrical loads.Item Economic impacts of the depletion of the Ogallala Aquifer: an application to the Texas High Plains(Texas Tech University, 1998-08) Terrell, BonnieNot availableItem Economic potential for development of increasing groundwater storage beneath a high plains municipality(Texas Tech University, 1987-12) Chen, Yu-ChiNot availableItem Field verification of a dual-porosity flow model to estimate aquifer recharge rates through playa lakes(Texas Tech University, 1996-05) Huda, Akm NazmulThe Southern High Plains of Texas overiies an extensive aquifer known as the Ogallala formation. This aquifer is the prime source of groundwater resources for this region. This aquifer has been experiencing severe depletion of its groundwater reserve due to the intensive use of water for irrigation. The natural recharge of this aquifer primarily depends on the surface mnoff water that is collected by a large number of playa lakes present in this region. The surface mnoff water retained by the playa lakes infiltrates through the playa beds and contributes to the groundwater recharge. However, the actual amount of recharge that takes place through playa beds is difficuh to quantify. Traditionally, recharge through playa lakes was estimated based only on micropore conductivity ofthe soil. However after long dry periods, playa beds tend to develop shrinkage cracks that increases the overall conductivity of soil significantly. Unfortunately, modeling the flow through a macropore system mathematicaUy is very difficult because ofthe complexities in the geometry and the spatial distribution of macropores. In a recent study, a numerical model, FTSCracks, was developed to incorporate the influence of shrinkage cracks on the overall flow rates through unsaturated soils. In FTSCracks, the systems of macropores were defined with some empirical parameters that were difficult to determine through lab tests. In this study, a series of lab and field experiments were performed to verify the FTSCracks model with field and lab data. This study was conducted also to demonstrate the ability of this model in estimation of aquifer recharge.Item Groundwater modeling for the Southern High Plains(Texas Tech University, 2001-05) Stovall, Jeff N.Not availableItem Importance and inclusion of Ogallala aquifer water issues in secondary agricultural education programs(Texas Tech University, 2003-12) Cox, Danielle MarieNot availableItem Infiltration through playa lake basin soils(Texas Tech University, 1990-12) Koenig, Gregory PaulNot availableItem Long-term capital budgeting analysis of alternative irrigation system investments in the Southern High Plains of Texas(Texas Tech University, 1987-08) Robison, Curtis DaleNot availableItem Mineralogy of the playa clays at the Pantex plant, Amarillo, Texas(Texas Tech University, 1996-08) Mars, Kenneth R.The Southem High Plains of Texas contains approximately 20,000 small ephemeral lake basins called playas. Recentiy, these playas have received considerable attention due to the realization that focused recharge to the Ogallala Aquifer can occur through these basins (Wood and Osterkamp, 1984, 1987; Scanlon et al., 1994; Wood et al., 1996). The Pantex Plant, located 16 miles northeast of Amarillo, Texas, in Carson County, has five playa lakes on property owned or leased by the Department of Energy. Potential contamination of the Ogallala Aquifer from Pantex has created much concern. Measurable contamination has been detected in the soils underlying the Plant (Laun, 1995). A sufficient knowledge of soil properties in playa basins is necessary to properly characterize the potential of contamination. Playa basins are a major focus of surface mnoff on the Southem High Plains. Playa basins have a distinctive surface soil, termed the Randall soil series (USDA-SCS unpublished material, 1978). Randall soils are defined as fine, montmorillonitic, thermic typic Halplustert. Playa basins collect mn-off from agricultural fields, roads, pavement and other man-made stmctures that can be sources of contamination. Mineralogy influences factors such as recharge and contaminant attenuation through these basins.Item Production and soil effects of sorghum biofuel cropping systems in semiarid marginal regions(2012-05) Cotton, Jon; Moore-Kucera, Jennifer; Acosta-Martinez, Veronica; Burow, Gloria B.; Wester, David B.In order to meet the growing demands for food, fiber, and biofuels, land management decisions will require identification of lands most suitable for each crop. Biofuel production that occurs on lands otherwise constrained for other intensive agricultural production by soil or water limitations (i.e., marginal lands) may not only meet some of these demands but, if managed properly, may also help improve soil function. For large-scale application to be sustainable, identification of crop type most efficient for feedstock production as well as impacts on soil and water resources are necessary. In this study, forage sorghum (Sorghum bicolor L. Moench) cropping systems were initiated in the semiarid Southern High Plains (SHP) of the U.S. to evaluate potential biofuel production and potential benefits on soils that are depleted of organic matter (< 0.7%) due to previous cropping history. Systems consisted of two sorghum cultivars (Sorghum Partners 1990 = SP 1990 and PaceSetter bmr = PS bmr) differing in lignin content due to brown midrib trait (bmr-12) that were tested under two different water levels (non-irrigated or deficit irrigation of 2.88 mm day-1), and biomass removal rate treatments of 50% and 100%. Forage sorghum SP1990 (non bmr) produced significantly higher weight and volumes of biomass than PS bmr under both deficit irrigation and no irrigation in the two years of study. However, PS bmr biomass was converted into ethanol (EtOH) 54% more efficiently during both years. When below average precipitation occurred during the first year of the study, both cultivars produced similar amounts of EtOH at each irrigation level (1,600 to 3,380 L ha-1). When higher than average precipitation occurred during the second year, higher biomass production of SP 1990 resulted in more EtOH production than PS bmr (3,380 vs. 2,640 L ha-1). Irrigation resulted in 26-49% more biomass and 28-72% more EtOH production during both growing seasons, indicating that non-irrigated production resulted in deficit water conditions regardless of precipitation. Overall EtOH production ranged from 1,600 to 3,380 L ha-1 during both years of the study. Changes in soil microbial properties (0-10 cm), known to be sensitive econsensors, were measured during the two year transition from previous long-term cotton cropping systems to the sorghum biofuel cropping systems. Increases in microbial biomass C (MBC) and N (MBN) (16-17%) and differences in fatty acid methyl ester (FAME) profiles were observed after one growing season. Additionally, soil enzyme activities (EAs) targeting C, N, P, and S increased 15-75% after two growing seasons. Increases in EAs 16-19%) and differences in FAME profiles were seen due to the irrigation treatment, which may be due to the increase in belowground biomass production even under deficit irrigation. When biomass was not fully removed (50% removal treatment), increases in MBC and MBN (11-15%), b-glucosidase (C cycling) and alkaline phosphatase (P cycling) (12-22%) occurred, which is likely attributed to the protection of the soil surface from aeolian erosion provided by the surface residue. The cultivars tested, which produced biomass with different chemical composition, had little effect on the soil microbial properties measured during the time frame of this study. This study indicates that chemical modifications and biomass yield potential are critical factors when selecting sorghum characteristics for use as biofuel feedstocks under marginal water-deficit conditions. These cropping systems also have the potential to improve sandy, low organic matter soils in this semiarid region, as was shown by increases in microbial biomass and soil functionality indicated by EAs after only two growing seasons. Early results from this study suggest sorghum biofuel cropping systems can be a sustainable practice for marginal lands in the SHP; however, tracking of long-term changes are necessary to fully evaluate effects. It is hypothesized that soil properties will continue to improve, especially in the lower biomass removal level as more above-ground biomass will be incorporated and decomposed. It is unclear how the chemical composition of biomass from different sorghum cultivars will impact soil properties but differences in organic matter accumulation and enhanced biochemical cycling are possible. Finally, additional research on incorporating biofuel production into traditional cotton production, along with the evaluation of novel sorghum cultivars specifically bred for use as feedstock, are important focuses for the application of biofuel production in the semiarid SHP.Item Simulation of unsaturated flow and heat transport within playa soils(2012-12) Pavur, Robert; Rainwater, Ken; Zartman, Richard E.; Stovall, Jeff N.; Gitz, DennisThe primary objective in this research was to use the observed data and an appropriate unsaturated flow model to estimate the amount of water that can pass the root zone and eventually recharge the Ogallala aquifer for particular playas following specific inundation periods. The first step in approaching this challenge was to screen the field data collected by the playa instrument stations. This step was necessary to determine which parts of the data set provided complete description of the necessary field conditions. The second step was to select a software package that employed input parameters available in this research project either through collected field data or previous study results. Third, the available input parameters were provided to the model, and calibration of the model was performed. Most input parameters were determined with relative ease while others presented difficult challenges, which indicated future research topics. Finally, the modeled results were produced to provide estimates of potential recharge.Item Soil-geomorphic relationships in the ancient Lake Lomax Basin, Southern High Plains(Texas Tech University, 1999-08) Cano-Garcia, Miguel A.The Lake Lomax Basin is on the southern margin of the High Plains in West Texas. Evidence suggests that it has been formed by subsidence/erosion processes in very eariy Pleistocene time and subsequent wind deflation. This study was conducted to determine the relationships between geomorphic surfaces and soil parent materials inside and outside of the basin and to generate information useful for a planned soil survey update. A preliminary study was conducted inside, as well as outside, of the basin. Clay mineralogy and particle-size distribution (PSD) analyses were used to differentiate between Blackwater Draw Formation and Ogallala Formation sediments. In the basin area, soil profile morphology was described along a 25-km east-west transect across the basin and along a 23-km north-south transect in the basin. Clay mineralogy, particle-size distribution, and selected chemical analyses were carried out. Particle-size distribution statistical parameters such as mean grain size, standard deviation, and skewness were used as criteria to discriminate among the different parent materials in transect samples.Item The Texas High Plains Aquifer system: modeling and projections for the southern region(Texas Tech University, 1996-05) Dorman, Troy M.The Texas High Plains is a region buih on irrigated agriculture. In 1989, over 65 percent of the total irrigated acreage in Texas, or 3.95 million acres, was located on the High Plains (Ashworth & Peckham 1993). Water for irrigation and many domestic supplies is pumped from the High Plains Aquifer System, with most coming from the Ogallala Aquifer. During the past five decades, water levels in the Ogallala have dropped dramatically because pumpage is much greater than recharge. Although the aquifer is large, it will eventually be depleted unless current withdrawal rates are decreased. The reductions could be accomplished either through voluntary conservation or government regulations. However, groundwater in Texas is presently the property of the landowner and cannot be controlled by state regulations. The solution to this problem lies in finding amenable methods to reduce pumpage and developing alternative sources of water for the region.Item Three Essays on Climate Change Impacts, Adaptation and Mitigation in Agriculture(2012-10-19) Wang, Wei WeiThis dissertation investigates three economic aspects of the climate change issue: optimal allocation of investment between adaptation and mitigation, impacts on a ground water dependent regional agricultural economy and effects on global food insecurity. This is done in three essays by applying mathematical programming. In the first essay, a modeling study is done on optimal temporal investment between climate change adaptation and mitigation considering their relative contributions to damage reduction and diversion of funds from consumption and other investments. To conduct this research, we extend the widely used Integrated Assessment Model?DICE (Dynamic Integrated Climate Economy) adding improved adaptation modeling. The model results suggest that the joint implementation of adaptation and mitigation is welfare improving with a greater immediate role for adaptation. In the second essay, the research focuses on the ground water dependent agricultural economy in the Texas High Plains Region. A regionally detailed dynamic land allocation model is developed and applied for studying interrelationships between limited natural resources (e.g. land and groundwater), climate change, bioenergy demands and agricultural production. We find out that the effect varies regionally across hydrologically heterogeneous regions. Also, water availability has a substantial impact on feedstock mix. In terms of biofuel feedstock production, the model results show that limited water resource cannot sustain expanded corn-based ethanol production in the future. In the third essay, a Computable General Equilibrium (CGE) model is applied in an attempt to study potential impacts of climate change on global food insecurity. Our results show that climate change alters the number of food insecure people in a regionally different fashion over time. In general, the largest increase of additional food insecure population relative to the reference case (no climate change) is found in Africa and South Asia, while most of developed countries will benefit from climate change with a reduced proportion of food insecure population. In general, climate change affects world agricultural production and food security. Integrated adaptation and mitigation strategy is more effective in reducing climate change damages. However, there are synergies/trade-offs between these two options, particularly in regions with limited natural resources.Item Towards a comprehensive regional water policy model for the Texas High Plains(Texas Tech University, 2004-12) Das, BiswaranjanIn Texas, irrigation groundwater withdrawals account for 90% of all Southern Ogallaia aquifer withdrawals. The reliance on groundwater to satisfy water demand in the Texas High Plains (THP) is attributable to limited surface supplies and the relatively high cost of developing surface water storage facilities. Beginning in the 1940's and extending into the early 1980's, improved irrigation technology facilitated the conversion of dryland acreage to irrigated acreage in the THP that resulted in the rapid depletion of Southern Ogallala aquifer's groundwater reserves, the only major groundwater source for the region. By the early 1990's, declining groundwater reserves in the Southern Ogallala aquifer had become a statewide concern for Texas policy makers and contributed to recent conservation legislation. Recent Texas legislation (Senate Bills 1 and 2) explicitly recognize the growing scarcity of Texas's groundwater supplies and requires the state to develop a comprehensive statewide water plan that incorporates locally developed regional water plans. In this dissertation, an integrated regional water policy model was developed by linking a spatially disaggregated hydrology model with a dynamic optimization model for 19 THP counties. The baseline scenario was first developed that simulated, over a 50 year planning horizon, the distribution of aquifer declines, crop pattern changes, and the net present value agricultural producers receive under current management practices. The effectiveness of two conservation policies, a groundwater extraction tax and quota restriction were then examined in terms of economic cost and volume of groundwater conserved relative to the baseline. The effectiveness of groundwater conservation tax under two alternate crop market price scenarios was then examined. Finally, the economic and hydrologic impacts of non-homogeneous land use within a county were assessed. Results indicated that current water conservation policies being considered for the THP did not significantly inhibit producer agricultural groundwater use over a 50 year planning horizon. In 13 of the 19 study region counties, water use was not binding. Both the Optimal Tax policy and the Quota policy conserved approximately the same amount of groundwater, but the total regional cost of the Optimal Tax policy to production agriculture was 8.56 times larger than for the Quota policy. Under both the price scenarios, the optimal tax was ineffective in curbing groundwater use. At the regional level, for each acre foot of groundwater conserved, the Optimal Tax policy cost $333 compared to the Quota policy cost of $40. Further, in addition to water use variability, due to the significant variation in land use within a county, the current groundwater conservation policies were not effective within all parts of a county and policy costs varied greatly over a county.Item Water conservation reserve program alternatives for the southern Ogallala aquifer(Texas Tech University, 2008-05) Wheeler, Erin Alexis; Johnson, Jeff; Segarra, Eduardo; Johnson, Phillip N.; Patterson, Dennis; Wang, ChenggangThe Ogallala Aquifer is a vast resource underlying parts of eight states. The southern portion of the Ogallala Aquifer is considered to be an exhaustible resource due to the relatively low level of recharge compared to the quantities of water pumped annually for the production of agricultural commodities. As the resource continues to be depleted, policy makers in several states including Texas are considering water conservation legislation. Society is likely to benefit more from water conservation policies in certain high water use counties which are rapidly depleting the saturated thickness of the aquifer, rather than a policy for the region as a whole. This study evaluates two water conservation policies for nine high water use counties in the Southern High Plains. The water conservation policies considered in this study include a ten year water rights buyout policy and a twenty year water rights buyout policy. The two policy scenarios require that 25% of a county’s irrigated acreage be transitioned into dryland production for the respective term of the buyout. After the term of the buyout has expired, enrolled acres are allowed to return to irrigated production. The basis for the two policy scenarios is the Conservation Reserve Program (CRP) policy enacted for soil conservation, but with a goal of water conservation. The models developed for this study were county level non-linear dynamic optimization models. Baseline scenario models where no change is made to current water policy were estimated along with the ten year and twenty year water rights buyout policy scenarios for three discount rates (3%, 6%, and 9%) in order to evaluate the role the chosen discount rate has on the net present value of net returns (NPV) and aquifer drawdown. The models differ from previous studies conducted on the Ogallala Aquifer due to the technological advancement parameters included. Results of the study indicate that the twenty year water rights buyout saves more water at a lower cost per foot of saturated thickness than the ten year buyout, but neither policy is restrictive enough to achieve significant conservation in the most depleting central counties of the study area.