摘要:

ABSTRACT:Over the last 30 years, average annual riverine flood damages have exceed $2 billion. Damages associated with the Mississippi River Flood of 1993 exceeded $12 billion and these costs do not include the non‐quantifiable, human impacts of this disaster. In a report submitted to the White House in June 1994, a federal interagency floodplain management review committee proposed better ways to manage the nation's floodplains. The committee indicated that the 1993 Mississippi River flood was the result of a significant hydrometeorological event, that federal flood control efforts in the Mississippi basin had prevented nearly $20 billion in potential damages, and that, in spite of federal flood damage reduction efforts, throughout the nation people and property remain at risk to inevitable future flooding. It recommended that the division of decision and cost‐sharing responsibilities among federal, state and local governments be more clearly defined, and that the nation adopt a strategy of, sequentially, avoiding inappropriate use of the flood‐plain, minimizing vulnerability to damage through both nonstruc‐tural and structural means, and mitigating damages as they occur. The report did not call for abandonment of human use of the flood‐plain but argued for full consideration of the economic, social and environmental costs and benefits of all future floodplain

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04024.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:A history of flood control in the United States shows an undying affair with levees. This love affair, however, was put severely to the test by the record flooding in the summer of 1993. About 70 percent of levees in the upper Midwest failed during this time, leading to extensive damage to both farmland and urban areas. Consequently, there were repeated calls to re‐assess the nation's floodplain management policies. The report of the Intera‐gency Floodplain Management Review Committee is one outcome of this and it forms the basis of this commentary on levees. In many respects, levees are effective flood control measures, being relatively cheap to implement and easy to build. At the same time, levees have negative impacts, affecting the hydrological regime both up and down stream, and often exacerbating flooding in other places. Furthermore, technical weaknesses in design, planning, construction, and maintenance have all contributed to levee failures. While the report recommends changes in floodplain management to address some of these issues, it is difficult to see how these will materialize given the current political, economic, and social clim

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04025.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Implementing ecosystem approaches to land use decision making and land management requires new methods for linking science and planning. Greater integration is crucial because under ecosystem management sustainable levels of resource use are determined by coupling management objectives to landscape capabilities and capacities. Recent proposals for implementing ecosystem management employ analyses organized at a hierarchy of scales for analysis and planning. Within this hierarchy, watershed analysis provides a framework for delineating the spatial distribution and linkages between physical processes and biological communities in an appropriate physical context: the watershed. Several such methods are currently in use in the western United States, and although there is no universal procedure for either implementing watershed analysis or linking the results to planning, there are a number of essential elements. A series of questions on landscape‐level ecological processes, history condition, and response potential guide watershed analysis. Individual analysis modules are structured around answering these questions through a spatially‐distributed, process‐based approach. The planning framework linked to watershed analysis uses this information to either manage environmental impacts or to identify desired conditions and develop land management prescriptions to achieve these conditions. Watershed analysis offers a number of distinct advantages over contemporary environmental analyses for designing land management scenarios compatible with balancing environmental and economic objec

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04026.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Water management in the United States has historically been characterized by a decisionmaking system that is fragmented along three dimensions: (1) physical, (2) institutional, and (3) political‐technical. The result is often ‘garbage can’ decision‐making in open decisionmaking structures with the attributes of an ‘organized anarchy’ rather than the rational, comprehensive decisionmaking prescribed for water management. A case study of water quality management decisionmaking in the New York Finger Lakes is used to illustrate how the garbage can model can illuminate the forces that operate in fragmented water management. Interorganizational decisionmaking theory and experience from water management integration initiatives are then applied to assess what strategies may be effective in reducing the organizational anarchy that results from fragmented water management i

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04027.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Nonpoint source ground water contamination by nitrate nitrogen (NO3‐N) leached from agricultural lands can be substantial and increase health risks to humans and animals. Accurate and rapid methods are needed to identify and map localities that have a high potential for contamination of shallow aquifers with NO3‐N leached from agriculture. Evaluation of Nitrate Leaching and Economic Analysis Package (NLEAP) indices and input variables across an irrigated agricultural area on an alluvial aquifer in Colorado indicated that all leaching indices tested were more strongly correlated with aquifer NO3‐N concentration than with aquifer N mass. Of the indices and variables tested, the NO3‐N Leached (NL) index was the NLEAP index most strongly associated with groundwater NO3‐N concentration (r2values from 0.37 to 0.39). NO3‐N concentration of the leachate was less well correlated with ground water NO3‐N concentration (r2values from 0.21 to 0.22). Stepwise regression analysis indicated that, although inorganic and organic/inorganic fertilizer scenarios had similar r2values, the Feedlot Indicator (proximity) variable was significant over and above the NO3‐N Leached index for the inorganic scenario. The analysis also showed that combination of either Movement Risk Index (MIRI) or NO3‐N concentration of the leachate with the NO3‐N Leached index leads to an improved regression, which provides insight into area‐wide associations between agricultural activities and ground wate

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04028.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:The biogeochemistry of a coastal old‐growth forested watershed in Olympic National Park, Washington, was examined. Objectives were to determine: (1) concentrations of major cations and anions and dissolved organic C (DOC) in precipitation, throughfall, stemflow, soil solution and the stream; (2) nutrient input/output budgets; and (3) nutrient retention mechanisms in the watershed. Stemilow was more acidic (pH 4.0–4.5) than throughfall (pH 5.1) and precipitation (pH 5.3). Organic acids were important contributors to acidity in throughfall and stemflow and tree species influenced pH. Soil solution pH averaged 6.2 at 40 cm depth. Stream pH was higher (7.6). Sodium (54.0 μeq L‐1) and Cl (57.6 μeq L−1) were the dominant ions in precipitation, reflecting the close proximity to the ocean. Throughfall and stemflow were generally enriched in cations, especially K. Cation concentrations in soil solutions were generally less than those in stemilow. Ion concentrations increased in the stream. Dominant ions were Ca (759.7 μeq L−1), Na (174.4 μeq L−1), HCO3(592.0 μeq L−1), and SO4(331.5 μeq L−1) with seasonal peaks in the fall. Bedrock weathering strongly influenced stream chemistry. Highest average NO3concentrations were in the stream (5.2 μeq L−1) with seasonal peaks in the fall and lowest concentrations in the growing season. Nitrogen losses were similar to inputs; annual inputs were 4.8 kg/ha (not including fixation) and stream losses were 7.1 kg/ha. Despite the age and successional status of the forest, plant uptake is an important N retention mec

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04029.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Delineation of a welihead protection area (WHPA) is the key element in welihead protection programs for drinking water supplies. WHPAs are often delineated under idealized conditions using simple steady‐state assumptions, which lead to an incorrect estimation of area and geometry. In this paper, we compare the results from a simple steady‐state procedure commonly employed in WHPA delineation with a more complex transient approach that allows consideration of seasonal variation in pumping rates. We also introduce a transient procedure to delineate time‐related capture zones using a numerical ground water flow and transport model. Welihead delineation is examined for two municipal wells in Tipton, Oklahoma, using a ten‐year time‐of‐travel criterion. In the steady‐state procedure, where we assumed constant pumping rates, we used GPTRAC, a semi‐analytical model, and MOC, a numerical model. The capture zone delineated by GPTRAC is comparable in shape with the capture zone delineated by MOC but not in size due to the differences in solution schemes. In the transient procedure, we used MOC and considered the seasonal variation in pumping rates. The capture zones delineated in this procedure were larger than the capture zones delineated by the steady‐state procedure using the same model. Further analysis showed that a higher drawdown was predicted in the transient procedure than in the steady‐state procedure, which is the reason for l

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04030.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Historically, dissolved‐oxygen (DO) data have been collected in the same manner as other water‐quality constituents, typically at infrequent intervals as a grab sample or an instantaneous meter reading. Recent years have seen an increase in continuous water‐quality monitoring with electronic dataloggers. This new technique requires new approaches in the statistical analysis of the continuous record. This paper presents an application of frequency‐duration analysis to the continuous DO records of a cold and a warm water stream in rural southwestern Wisconsin. This method offers a quick, concise way to summarize large time‐series data bases in an easily interpretable manner. Even though the two streams had similar mean DO concentrations, frequency‐duration analyses showed distinct differences in their DO‐concentration regime. This type of analysis also may be useful in relating DO concentrations to biological effects and in predicting low D

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04031.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Fuels contained in underground storage tanks (USTs) are a major source of soil and ground water contamination. Effective management of the problem at the urban level is difficult due to a large number of tanks and a vast array of factors (e.g., tank characteristics, geology) that determine environmental hazards. The problem is compounded by frequent abandonment and reuse of service stations, which makes it difficult to track the status of underground tanks. Geographic information systems (GIS) are ideally suited to organizing location and attribute data for variables that are pertinent to the UST management problem. A GIS‐based UST management system was developed and applied to 136 current and former gasoline service stations in Denton, Texas. The system is effective for tank inventory and can be applied in a proactive fashion to identify potentially problematic facilities. In the event of a leak or spill, the management system can support the implementation of reactive measures to mitigate subsurface contamination. Potential beneficiaries of such a system include planning departments, environmental regulatory agencies, emergency management officials, lending institutions, gasoline distributors, and oil companie

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04032.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Historically ephemeral washes in the Las Vegas Valley have become perennial streams in the urbanized area, and the primary source of these perennial flows appears to be the overirrigation of ornamental landscaping and turf. Overirrigation produces direct runoff to the washes via the streets and results in high ground water levels in some areas. Elevated ground water levels result in discharge to the washes because of changes in the natural balance of the hydrologic system and construction site and foundation dewatering. In recognition of the resource potential of these flows within the Las Vegas Valley, of the potential for dry weather flows to convey pollutants from the Valley to Lake Mead, and of the need to characterize dry weather flows under the stormwater discharge permit program, the quantity and quality of dry weather flow in Flamingo Wash was investigated during the period September 1990 through May 1993. This paper focuses on the resource potential of the flow (quantity and quality) as it relates to the interception and use of this water within the Valley. Economic and legal issues associated with the interception and use of this resource are not considered here.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb04033.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY