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31.
Mingteh Chang Jack D. McCullough Alfredo B. Granillo 《Journal of the American Water Resources Association》1983,19(2):191-196
ABSTRACT: Spatial variation of five water quality variables were analyzed using composite water samples collected periodically from eight small watersheds (11.4–71.6 km2) in forested East Texas during 1977 through 1980. Based on 31 observations during the four-year period the average yield of nitrate-nitrite nitrogen (NNN), total kjeldahl nitrogen (TKN), total phosphorus (PO4), chloride (CHL), and total suspended sediment (TSS) were 1.43, 21.96, 3.09, 50.11, and 90.39 ka/ha/yr, respectively. Compared to the water quality standards of the U.S. Environmental Protection Agency (1976) and the Texas Department of Water Resources (1976) for CHL, TSS, and NNN, none of the observations exceeded the limits for public water supplies. The study showed that forested watersheds normally yielded stream flow with better quality than that from agricultural watersheds. Watersheds of greater percent of pasture area, mean slope, stream segment frequency, and drainage density produced greater concentrations for these five chemical parameters in water samples. Meaningful equations were developed for estimating mean average yields for each chemical parameter for each watershed with R2 ranging from 0.77 to 0.96 and standard error of estimates from 17 to 33 percent of the observed means. 相似文献
32.
Fred M. Shelley F. Andrew Schoolmaster Rebecca S. Roberts 《Journal of the American Water Resources Association》1986,22(3):485-493
ABSTRACT: Since 1957, Texans have had the opportunity to vote on eight referenda concerning the allocation of state funds for water resources development and the maintenance of water quality. In 1976, a water development amendment and a water quality amendment were presented simultaneously to the voters of Texas, affording a unique opportunity for electoral-geographic comparison of county-level returns on the two issues. In this paper, cartographic and statistical analyses of the county-level voting outcomes for each referendum are presented. In both cases, the referenda were supported by voters in water-deficient West Texas, especially those counties dependent on irrigated crop production. In contrast, urban voters and East Texans tended to oppose both amendments. However, support for the water quality amendment in the urbanized areas of Dallas-Fort Worth, Austin, and San Antonio enabled this amendment to pass statewide while its counterpart failed. The results highlight the importance of local differences in perceived water policy needs, and in doing so they illustrate that geographical anlaysis of returns from initiatives and referenda is a useful tool for understanding the locational conflicts underlying water resources and other policy efforts. 相似文献
33.
Identifying Potential Conflict Associated with Oil and Gas Exploration in Texas State Coastal Waters: A Multicriteria Spatial Analysis 总被引:1,自引:0,他引:1
Brody SD Grover H Bernhardt S Tang Z Whitaker B Spence C 《Environmental management》2006,38(4):597-617
Recent interest in expanding offshore oil production within waters of the United States has been met with opposition by groups
concerned with recreational, environmental, and aesthetic values associated with the coastal zone. Although the proposition
of new oil platforms off the coast has generated conflict over how coastal resources should be utilized, little research has
been conducted on where these user conflicts might be most intense and which sites might be most suitable for locating oil
production facilities in light of the multiple, and often times, competing interests. In this article, we develop a multiple-criteria
spatial decision support tool that identifies the potential degree of conflict associated with oil and gas production activities
for existing lease tracts in the coastal margin of Texas. We use geographic information systems to measure and map a range
of potentially competing representative values impacted by establishing energy extraction infrastructure and then spatially
identify which leased tracts are the least contentious sites for oil and gas production in Texas state waters. Visual and
statistical results indicate that oil and gas lease blocks within the study area vary in their potential to generate conflict
among multiple stakeholders. 相似文献
34.
Floods continue to pose the greatest threat to the property and safety of human communities among all natural hazards in the United States. This study examines the relationship between the built environment and flood impacts in Texas, which consistently sustains the most damage from flooding of any other state in the country. Specifically, we calculate property damage resulting from 423 flood events between 1997 and 2001 at the county level. We identify the effect of several built environment measures, including wetland alteration, impervious surface, and dams on reported property damage while controlling for biophysical and socio-economic characteristics. Statistical results suggest that naturally occurring wetlands play a particularly important role in mitigating flood damage. These findings provide guidance to planners and flood managers on how to alleviate most effectively the costly impacts of foods at the community level. 相似文献
35.
Associations between groundwater quality and land usewere evaluated in the southeastern Gulf Coast Aquifer,Texas. Data from 19 234 oil/gas wells and 256 water wellswere mapped with a geographic information system (GIS) andstatistically analyzed. Water wells near oil/gas wells hadsignificantly higher levels of chloride, bromide, and totaldissolved solids (TDS). Bromide-chloride ratios were alsohigher at water wells near oil/gas wells. Shallower waterwells had significantly higher chloride, bromide, TDS, andnitrate concentrations. Nitrate concentrations were higherbeneath cropland compared to other land uses. Results ofthis study suggest that oil/gas production and agriculturehave impacted water quality in the Gulf Coast Aquifer. 相似文献
36.
Alan E. Fryar Stephen A. Macko William F. Mullican III Katherine D. Romanak Philip C. Bennett 《Journal of contaminant hydrology》2000,40(4)
In arid and semi-arid environments, artificial recharge or reuse of wastewater may be desirable for water conservation, but NO3− contamination of underlying aquifers can result. On the semi-arid Southern High Plains (USA), industrial wastewater, sewage, and feedlot runoff have been retained in dozens of playas, depressions that focus recharge to the regionally important High Plains (Ogallala) aquifer. Analyses of ground water, playa-basin core extracts, and soil gas in an 860-km2 area of Texas suggest that reduction during recharge limits NO3− loading to ground water. Tritium and Cl− concentrations in ground water corroborate prior findings of focused recharge through playas and ditches. Typical δ15N values in ground water (>12.5‰) and correlations between δ15N and ln CNO−3–N suggest denitrification, but O2 concentrations ≥3.24 mg l−1 indicate that NO3− reduction in ground water is unlikely. The presence of denitrifying and NO3−-respiring bacteria in cores, typical soil–gas δ15N values <0‰, and decreases in NO3−–N/Cl− and SO42−/Cl− ratios with depth in cores suggest that reduction occurs in the upper vadose zone beneath playas. Reduction may occur beneath flooded playas or within anaerobic microsites beneath dry playas. However, NO3−–N concentrations in ground water can still exceed drinking-water standards, as observed in the vicinity of one playa that received wastewater. Therefore, continued ground-water monitoring in the vicinity of other such basins is warranted. 相似文献
37.
J. H. Krishna G. F. Arkin J. R. Martin 《Journal of the American Water Resources Association》1987,23(6):1057-1061
ABSTRACT: The current increase in the demand for water by municipal, industrial, and other users is likely to result in approximately one-third less water being available for agricultural use in Texas by the year 2000. As water supplies diminish, the rainfall excess needs to be used more efficiently. Large amounts of runoff occur in the eastern part of Texas that could be collected in small impoundments and utilized for crop production. Farmers in water-surplus basins or subbasins can apply for a permit to divert surface water into small on-farm impoundments to be used for supplemental irrigation. The costs for runoff collection and two supplemental irrigations, which amount to a total of 4 in./yr., are estimated to be approximately $60/acre/year. Depending upon the crop produced, the estimated increase in gross income from supplemental irrigation ranges from about $80 to more than $100 per acre annually. 相似文献
38.
A geographic information system was used to map and analyze nitrate, chloride, sulfate, and fluoride concentrations in 110 wells tapping the Woodbine Aquifer. The study area, covering ninecounties in north-central Texas, includes large percentages of both urban and agricultural land uses. Land use maps were compared with solute concentration data, and statistics were applied to detect associations between solutes, well depth, andland use. Anthropogenic sources such as fertilizer applications and natural sources such as gypsum, lignite, and clay deposits controlled nitrate, chloride, and sulfate concentrations, each inversely correlated with well depth. However, only one nitrate observation – from a shallow well in the aquifer's outcrop zone – surpassed the maximum contaminant level (MCL) of 44.3 mg L-1. By comparison, nearly half of the sulfate and several of the chloride observations surpassed the MCL of 250 mg L-1for each of those ions. Volcanic ash deposits influenced fluorideconcentrations, which directly correlated with well depth. There were no statistically significant associations between solute concentrations and land use. Low recharge rates and confining layers have mitigated anthropogenic impacts on solute levels in the aquifer. 相似文献
39.
Otis W. Templer 《Journal of the American Water Resources Association》1980,16(2):305-311
ABSTRACT: This paper examines the critical interaction between existing Texas water law and the state's water resources. Conjunctive use and management of interrelated water resources, though seldom practiced, is generally considered desirable. However, a significant barrier to the coordinated, efficient use and management of water resources is the legal division of water in the various phases of the hydrologic cycle into different classes and recognition of well-defined water rights in the separate phases. Several examples of the problems which relate to, or result from, present Texas water law and which prevent correlated water resource management are discussed. Any substantive revision of Texas law, particularly ground water law, will apparently be difficult to achieve in the immediate future, primarily because of the large number of recognized private water rights and the political power inherent in them. Data necessary for operation of conjunctive management systems are gradually being acquired, and perhaps someday other hydrologic phases can be integrated with surface and ground water. Nevertheless, Texas courts and the legislature have sufficient information on the interrelated hydrologic cycle so that prospective water conflicts should be anticipated and avoided. Great care must be exercised in the recognition of new types of private water rights or extension of existing rights, because this institutional structure, once established, presents a formidable obstacle to desirable revisions of the law. 相似文献
40.
A method is presented which combines environmental indices and estimates of inputs from various land uses to aid in environmental impact assessments. Unweighted pair/group cluster analyses are used to obtain relationships between easily observable environmental indices, such as vegetation types, soils, and geology, based on their mutual recurrence. These relationships are shown by using an ordination technique which shows the nature of complex impacts on a natural system. Results are used to develop anenvironmental effects sequence diagram based on known scientific and engineering principles and observed natural relationships. The diagram may be used in conjunction with land use data to estimate the possible magnitude of impacts on the pre-existing system which may result from such land use. Several examples are developed which quantify inputs from various land uses and which compare them with environmental inputs including point source and non-point source liquid and atmospheric emmissions, land modifications, and resource consumption. Known average values are used and a separate comparison is made in describing the vast differences between the project phases of construction versus longterm operation. A hypothetical environmental impact assessment is given for a small residential development in Chambers County, Texas, U.S. of A. 相似文献