Browsing by Subject "Aquifers -- Texas"
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Item Ground-water geochemistry of the Ogallala Aquifer in the Southern High Plains of Texas and New Mexico(Texas Tech University, 1980-12) Potratz, Victoria YekoConcentrations of calcium, magnesium, potassium, sulfate, and chloride ions in the ground water generally increase from the north to the south in the Ogallala Aquifer of the Southern High Plains of West Texas and eastern New Mexico. In the south, higher concentrations of solutes generally occur in areas which are underlain by Cretaceous rocks and are located beneath large saline lakes. The distribution of bicarbonate and flouride ions and also silica molecules are variable throughout the aquifer. High concentrations of nitrate ions usually occur south of the northern edge of the Cretaceous boundary and along the northeastern edge of the aquifer. The primary sources of solutes in the ground water north of the Cretaceous subcrop are the weathering and dissolution of potassium feldspar, biotite, plagioclase feldspar, calcite, and dolomite. Minor amounts of sodium, sulfate, and chloride may have been added to the ground water by seepage of oil and gas field brines into the aquifer. It is proposed that ground water south of the Cretaceous subcrop obtains additional sodium, sulfate, and chloride ions from the mixing of saline Cretaceous water with the Ogallala water. The mixing between the two aquifers may result from a difference in head between the two aquifers or by diffusion. In these areas of mixing, the sodium ions from the Cretaceous water may be exchanging for calcium and magnesium ions on clay minerals in the Ogallala Formation. Some of the calcium ions produced from the exchange are probably combining with bicarbonate ions and precipitating calcium carbonate. Amorphous silica and flourite may be precipitating in several areas of the aquifer along with calcite and is probably limiting the concentrations of silica, flourine, calcium, and to a minor degree bicarbonate.Item Origin of solutes in groundwaters of clastic silicate aquifers(Texas Tech University, 1981-08) Mauser, John KemmerNot availableItem Preliminary investigation of the sedimentary zonation of the Ogallala aquifer, southern High Plains(Texas Tech University, 1979-08) Buika, Paul HThe Ogallala aquifer of the Southern High Plains provides water from approximately 60,000 irrigation walls (Don Smith, personal communication, 1979), which support 68 percent of the total irrigated acreage in Texas. However, because the Southern High Plains is a topographically isolated plateau, the Ogallala aquifer receives no recharge except from infiltration of surface precipitation. The region is a semi-arid area, receiving only approximately 19 inches precipitation par year; thus a declining water table will soon reduce irrigated acreage to about 60 percent of today's figure by the year 1990. Source areas for Ogallala sediments ware the Southern Rocky Mountains of New Mexico, although the exact areas have yet to be determined. Deposition of coarse Ogallala sediments first occurred by valley alluviation in pre-Ogallala drainage channels, followed by meandering stream deposition of fine-grained sands and clays, and deposition of considerable aeolian debris. Sands, clays, and gravels are interspersed throughout the Ogallala section making correlation difficult. However, maps representing the distribution of sand, clay, and gravel units of the Ogallala Group do show soma regional continuity. Clay distribution in the Ogallala section thins to the east-northeast, although several thick local clay sections occur; these may represent ancient lacustrine deposits. Clay thicknesses, which range up to 320 feet, may account for up to 70 percent of the Ogallala section. Sand lenses in the Ogallala of the Southern High Plains range up to 450 feet in thickness, and often account for 100 percent of the section. Ogallala sands are generally thicker than either clay or gravel accumulations, regionally thinning to the southeast. Gravels in the Ogallala aquifer, with the exception of the widespread basal zone, thin eastward. Elongation of two gravel trends from northwest to southwest is a product of the two major stream channels which ware active during much of the Ogallala time. A third major Ogallala-age stream channel may have existed in the area now occupied by the Canadian River Valley, as indicated by the gravels that occur in Carson County.Item Sedimentary zonation of the Ogallala Aquifer(Texas Tech University, 1980-12) Smelley, Randal KeithThe Ogallala aquifer of the Southern High Plains, composed mainly of sands and gravels underlain by older rocks of lower permeability, is the most extensive and usable aquifer of the Great Plains province (Frye, 1970). Natural recharge of the Ogallala section in West Texas and eastern New Mexico is restricted to percolation of precipitation and playa lake seepage within a semi-arid environment (approximately 19 inches of precipitation per year). Excessive withdrawal from the Ogallala aquifer, particularly for agricultural purposes, is lowering the water table at a rate that will reduce irrigated acreage to about 60 percent of today's figure by the year 1990 (Buika, 1979). Initial deposition of Ogallala sediments, derived from the Southern Rocky Mountains of New Mexico, occurred as valley alluviation in pre-Ogallala drainage channels. Clays and fine-grained sands were later deposited by streams meandering across the alluvial plain which formed as a result of the filled channel valleys. Fine-grained eolian sands were deposited in addition to flood plain sediments. Correlation of individual units within the Ogallala section is difficult, although some stratigraphic continuity is evident from regional maps of sand, clay, and gravel distribution. Sand accounts for 100 percent of the Ogallala section in various localities through Quay and Curry County, but thins to the southeast. Thickness ranges from 20 to over 300 feet. Clay in the Ogallala section thickens to the north and northeast, ranging from zero in eastern New Mexico (Lea and Roosevelt counties) to over 300 feet in the northeastern section of the study area (Carson County). Thick localized clay lenses, apparently representing lacustrine environments, occur throughout the Southern High Plains. The basal gravel of the Ogallala section reveals several thick elongated accumulations indicative of pre- Ogallala drainage channel fill. Gravels throughout the remainder of the Ogallala section are thin and discontinuous, the overall amount of gravel in the section thinning to the east. Localized abnormally thick accumulations of gravel may have resulted from sink fillings. Standard deviation values calculated for each lithologic unit are interpreted relative to geological explanations of data variance. The ratio of sand and gravel to clay was determined to assess the relation of highly porous and permeable sediments to sediments of low porosity and permeability. Sand and gravel to clay ratio values range from 1 to 4 for most of the central Southern High Plains, increasing sharply (up to 100) through eastern New Mexico.Item The Effects of Aquifer Characteristics and Other Factors on Land Values in the Southern High Plains of Texas, 1974-1979(Texas Tech University, 1982-08) Mathews, Kenneth HarryThis thesis examlned the characteristics associated with individual land parcels that were actually sold during 197^ through 1979 for the 15-county area of the Ogallala Aquifer in the Southern High Plains of Texas. The sample examined represented over 90 percent of the total number of parcels sold for the study period. Characteristics associated with the aquifer, that is the gallons per minute potential, the size in acres of a parcel, and the distance in miles from the closer of Lubbock or Amarillo,were found to have the greatest impact of those studied on the price per acre of rural land in the study area. The parameter estimates, which were also the price elasticities with respect to the characteristics, were 0.3103, -0.28U3 and -O.2961, respectively. All of the variables studied yielded parameter estimates that were statistically significant except the natural log of the pumping lift in Model 3. However, on a county by county basis there were several parameter estimates found to be not statistically significant.Item The effects of aquifer characteristics and other factors on land values in the Southern High Plains of Texas, 1974-1979(Texas Tech University, 1982-08) Mathews, Kenneth HarryThis thesis examined the characteristics associated with individual land parcels that were actually sold during I97U through 1979 for the 15-county area of the Ogallala Aquifer in the Southern High Plains of Texas. The sample examined represented over 90 percent of the total number of parcels sold for the study period. Characteristics associated with the aquifer, that is the gallons per minute potential, the size in acres of a parcel, and the distance in miles from the closer of Lubbock or Amarillo, were found to have the greatest impact of those studied on the price per acre of rural land in the study area. The parameter estimates, which were also the price elasticities with respect to the characteristics, were 0.3103, -O.28U3 and -O.296I, respectively. All of the variables studied yielded parameter estimates that were statistically significant except the natural log of the pumping lift in Model 3. However, on a county by county basis there were several parameter estimates found to be not statistically significant.