A forest fire can be a real ecological disaster regardless of whether it is caused by natural forces or human activities, it is possible to map forest fire risk zones to minimize the frequency of fires, avert damage, ...
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A forest fire can be a real ecological disaster regardless of whether it is caused by natural forces or human activities, it is possible to map forest fire risk zones to minimize the frequency of fires, avert damage, etc. A method integrating remote sensing and GIS was developed and applied to forest fire risk zone mapping for Baihe forestry bureau in this paper. Satellite images were interpreted and classified to generate vegetation type layer and land use layers (roads, settlements and farmlands). Topographic layers (slope, aspect and altitude) were derived from DEM. The thematic and topographic information was analyzed by using ARC/INFO GIS software. Forest fire risk zones were delineated by assigning subjective weights to the classes of all the layers (vegetation type, slope, aspect, altitude and distance from r3ads, farmlands and settlements) according to their sensitivity to fire or their fire-inducing capability. Five categories of forest fire risk ranging from very high to very low were derived automatically. The mapping result of the study area was found to be in strong agreement with actual fire-affected sites.
Tidal freshwater marshes have diverse plant communities that vary spatially and temporally due to hydrology, animal activity, and other factors. Development of urban centers along rivers of the U.S. Atlantic coast has...
Tidal freshwater marshes have diverse plant communities that vary spatially and temporally due to hydrology, animal activity, and other factors. Development of urban centers along rivers of the U.S. Atlantic coast has reduced the historic extent and quality of these and other coastal wetlands. Because the vegetation of these wetlands is more complex than that of salt and brackish marshes (where restoration of vegetation typical of natural systems has sometimes been successful), restoration of tidal freshwater marsh vegetation is likely to be more difficult, particularly in urban areas. Watershed urbanization alters hydrology, sediment load, propagule availability and composition, nutrient status, and other variables that together create an environment different from that of wetlands in less developed areas, possibly precluding restoration of typical marsh vegetation. Tidal freshwater wetlands were historically extensive along the Anacostia River in Washington, DC, but most of these were lost due to filling, dredging, or hydrologic alteration. Over the last decade, the U.S. Army Corps of Engineers has implemented projects designed to restore tidal freshwater wetlands along the Anacostia, which involved increasing elevation with dredged river sediment and planting native vegetation. To illustrate some of the mechanisms affecting vegetation development in restored tidal freshwater marshes in urban areas, I present a case study on one of these wetlands, Kingman Marsh, that also includes research at another restored wetland and two natural reference sites. Studies by my research groups indicate that the restored wetlands undergo essentially a planting-modified process of primary succession. Low densities of seeds are initially present in the substrate, and prolific seed dispersal into the restored sites results in high initial plant diversity comprised of plantings and ruderal (i.e. weedy) natives and exotics. Seed banks develop rapidly at the restored sites, probably du
作者:
Nyer, EKMayfield, PHughes, JEvan K. Nyer is a vice president with ARCADIS Geraghty & Miller Inc.
where he is responsible for maintaining and expanding the company's technical expertise in geology/hydrogeology engineering modeling risk assessment and bioremediation. He has been active in the development of new treatment technologies for many years. His areas of research interest include biological treatment suspended solids separation chemical oxidation in situ treatment air treatment systems and the application of new technologies to ground water cleanup. He has been responsible for the strategies technical design and installation of more than 200 ground water and soil remediation systems at contaminated sites throughout the United States. Paulette Mayfield is the project manager for engineering services in ARCADIS Geraghty & Miller Inc. 's Austin
Texas office. As such she manages engineering projects conducted by the office and also provides engineering and regulatory support for projects conducted by ARCADIS Geraghty & Miller nationwide. She is also a member of ARCADIS Geraghty & Miller's compliance audit team and has participated in or managed numerous projects associated with RCRA program compliance solid and hazardous waste management regulatory analysis and compliance planning and facility closure/demolition/ property redevelopment. She has participated in the design operation management and evaluation of numerous bioremediation projects including hazardous waste land treatment units petroleumcontaminated soil remediation projects and ground water natural attenuation and enhanced natural attenuation projects. Mayfield also conducted two years of laboratory research involving the in situ biodegradation of petroleum products. She received her graduate degree in environmental engineering from Texas Tech University and has co-authored several publications addressing in situ bioremediation techniques. Joseph D. Hughes is a hydrogeologist in ARCADIS Geraghty & Miller's Tampa
Florida office. His areas of research int
The historical analytical data collected at Murdock demonstrate that: Constitutent concentrations in ground water in the area of highest known contaminant concentrations and along the flow path downgradient of that ar...
The historical analytical data collected at Murdock demonstrate that: Constitutent concentrations in ground water in the area of highest known contaminant concentrations and along the flow path downgradient of that area decreased over the 3.5-year period when we began monitoring at the site and when we conducted the biogeochemical study. The ground water plume has stabilized and will not move further south. Chlorinated hydrocarbon parent products (TCE and 1,1,1-TCA) are degrading to their daughter products (1,1-DCA, 1,1-DCE, and cis-1,2-DCE) and thence to VC. The estimated total mass of chlorinated hydrocarbons dissolved in ground water was reduced from 1032 to 346 pounds between 1993 and the end of 1996 (approximately 66%). However, the scoring from the AFCEE protocol showed that there was only 'limited' evidence of biological dechlorination occurring at the site.
This study compares kriging and maximum entropy estimators for spatial estimation and monitoring network design. For second-order stationary random fields (a subset of Gaussian fields) the estimators and their associa...
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This study compares kriging and maximum entropy estimators for spatial estimation and monitoring network design. For second-order stationary random fields (a subset of Gaussian fields) the estimators and their associated interpolation error variances are identical. Simple lognormal kriging differs from the lognormal maximum entropy estimator, however, in both mathematical formulation and estimation error variances. Two numerical examples are described that compare the two estimators. Simple lognormal kriging yields systematically higher estimates and smoother interpolation surfaces compared to those produced by the lognormal maximum entropy estimator. The second empirical comparison applies kriging and entropy-based models to the problem of optimizing groundwater monitoring network design, using six alternative objective functions. The maximum entropy-based sampling design approach is shown to be the more computationally efficient of the two.
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