岸坡侵蚀及其防治

岸坡侵蚀是土地侵蚀的一个类型．它进一步又可划分为岸坡崩塌、滑坡侵蚀，岸坡塌陷侵蚀，岸坡沟谷侵蚀和岸坡洪水侵蚀。本文在详细分析各类岸坡侵蚀的基础上，提出了岸坡侵蚀的特点和防治对策。     

Changes in flood-plain vegetation and land use along the Missouri River from 1826 to 1972

Changes in vegetation and land use since 1826 were evaluated along the 800 kilometer portion of the Missouri River flood-plain that extends across the State of Missouri using County Land Office Survey records for 1826 and aerial photos for 1937, 1958, and 1972. The combined results show a decline in flood-plain forest coverage from 76% in 1826 to 13% in 1972; cultivated land increased from 18% to 83% during the same time. Uncultivated-unforested areas increased from 6% in 1826 to 27% in 1937, then declined to 1% in 1972; these changes occurred coincident with extensive bank-stabilization and channelization activities initiated in 1912 by the U.S. Army Corps of Engineers. Riverbank stabilization activity since that time may account for the increased rate of decline in flood-plain forests from 0.25% per year between 1826 and 1937 to 1.6% per year between 1937 and 1972.The overall species composition of the 1826 flood-plain forests was found to be most similar to mature forest stands evaluated in 1972; similar frequencies in 1826 and 1972 occurred for hackberry (Celtis occidentalis; 80% in 1826, 83% in 1972), elm (Ulmus spp.; 80% and 83%), and sycamore (Platanus occidentalis; 57% and 50%). Pawpaw (Asimina triloba), found only in mature flood-plain forests in 1972, was recorded along 54% of the 1826 section lines.These combined data indicate (1) that pre-settlement flood-plain forests were extensive and included frequent, mature stands, (2) that in certain areas substantial portions of the flood-plain were in cultivation prior to extensive riverbank stabilization and channelization, and (3) that increased flood-plain forest clearing occurred coincident with increased bank-stabilization activities.     

Geographic information systems and environmental impact assessment

The analytical structure of environmental impact assessment is continually changing as the applicability of established techniques from other fields and the development of novel methods become known. This paper illustrates the applicability of using existing data bases, through a geographic information system, for theex ante evaluation of land use disruption. More specifically, the Canada Geographic Information System was employed to retrieve, to analyze, and to produce land capability statistics and land use maps for the proposed Glengowan dam and reservoir.     

Air quality assessment for land disposal of industrial wastes

Air pollution from hazardous waste landfills and lagoons is largely unknown. Routine monitoring of toxic air contaminants associated with hazardous waste facilities is difficult and very costly. The method presented in this paper would be useful for air quality assessment in the absence of monitoring data. It may be used as a screening process to examine the question of whether or not volatilization is considered to be significant for a given contaminant and also to evaluate permit applications for new hazardous waste facilities concerning waste volatilization problems.     

Natural resource planning: An urban prospective

The use and development of natural resources is becoming a critical concern, especially considering the economic development and stability of the world money market. The question here is one of resources as a political weapon. As resources become more scarce, it becomes necessary to make greater intensive use of resources that are presently available. One dimension that has been missing is the development of urban areas. Resources in this domain have been abused and the question now is how to incorporate these types of decisions into land-use planning to refurbish urban areas. Planning is the key to use of a resource. The world can no longer afford crisis planning. The key dimension to future success in resource problems is preventive planning.     

A framework for profiling a lake's riparian area development potential

Some of the greatest challenges for managing residential development occur at the interface between the terrestrial and aquatic ecosystems--in a lake's riparian area. Land use planners need a framework they can use to identify development hotspots, areas were the next push for development will most likely occur. Lake riparian development profiles provide a framework for linking ecological and social factors important to development. In a test of this framework in northern Minnesota, researchers identified seven constructs influencing riparian area development: current general development, current housing development, and availability, accessibility, suitability, aesthetics, and proximity to services. Profiles display a lake's value for each construct relative to the range of values for all lakes in the county. Maps, developed using indicators for several constructs, allow us to identify how the factors interact and are dispersed across the landscape. These profiles help policy makers, planners, and managers identify lakes that are potential development hotspots so they can take timely steps to manage development or control the impacts of development.     

Land-Cover Assessment of Conservation and Buffer Zones in the BOSAWAS Natural Resource Reserve of Nicaragua

The BOSAWAS Natural Resource Reserve of Nicaragua was established in 1991, to protect a portion of the remaining tropical rain forest and to promote the sustainable use of the region's resources. Information required to effectively manage the reserve includes the extents and locations of present land-cover types and recent land-cover changes in the management use zones that were delineated by local indigenous communities. These zones include areas designated for conservation, limited resource extraction, agriculture, and watershed protection. Land-cover for 1986 and 1995 was identified for three of the communities from remotely sensed images and then input into a geographic information system database to identify land-cover types within these management use zones. For both dates of the analysis, advanced forest was the dominant land cover, with the conservation zones entirely forested. The amount of both agricultural land and scrub/early secondary forest increased between the two dates, with much of these land-cover classes occurring in the agriculture zones. Conflicts between the land-cover present and designated use were identified in some of the limited-use buffer and watershed protection zones. Changes between 1986 and 1995 were identified by overlaying the two land-cover data sets. Three change processes were identified as occurring: deforestation, reforestation, and reconversion. Changes were concentrated in the agriculture zones but were found to occur in every type of zone, except for conservation. The results of this study will establish baseline information for the future management of the BOSAWAS Reserve, an important component in uniting conservation areas along the Central American isthmus.     

Landscape Changes in the Mullica River Basin of the Pinelands National Reserve,New Jersey,USA

In 1979, the Pinelands Commission was established as a regional land-use planning and regulatory agency charged with the implementation of a Comprehensive Management Plan (CMP) for the Pinelands National Reserve (New Jersey, USA). The CMP was created to balance land preservation and development interests in the Reserve. Because water-quality degradation from developed and agricultural landscapes is associated with changes in the composition of biological communities, monitoring landscape changes provides one of the most direct measures of the impact of land-use policies on the Pinelands ecosystem. In this study, we prepared detailed, land-cover maps within randomly selected aerial-photograph plots for a major watershed in the Reserve. We used these land-cover maps to quantify changes in landscape composition and structure (i.e., patch size, patch area, and number of patches) and characterize land-cover transitions in the basin between 1979 and 1991. Because the study period represented the first 12 years of the regional-planning effort in the Reserve, we evaluated the relationship between land-cover transitions and Commission management-area designations which permit different land-use intensities. Although the landscape composition was similar in 1979 and 1991, we found an increase in the total area and number of developed-land, managed-grassland, and barren-land patches. An increase in the number of patches and a decrease in the total area and median and third-quartile patch sizes for forest land and for all patches regardless of cover type indicated that fragmentation of forest land and the landscape as a whole occurred during the study period. The major land-cover transitions that occurred during the period were the loss of forest land to development and associated cover types and the conversion of one agricultural type to another. Overall, land-cover transitions during the period were found to be consistent with the Commission management-area designations, which indicated that the regional-planning effort has been successful in directing human activities to appropriate areas of the basin.     

Evaluating Ecosystem Management Capabilities at the Local Level in Florida: Identifying Policy Gaps Using Geographic Information Systems

Because ecosystem approaches to management adhere to ecological systems rather than human-defined boundaries, collaboration across jurisdiction, agencies, and land ownership is often necessary to achieve effective management of transboundary resources. Local natural resource and land use planners increasingly recognize that while ecosystem management requires looking beyond specific jurisdictions and focusing on broad spatial scales, the approach will partly be implemented at the local level with the coordination of local policies across larger landscapes. This article evaluates the collective capabilities of local jurisdictions to manage large transboundary ecological systems in Florida. Specifically, it combines plan evaluation with geographic information systems (GIS) techniques to map, measure, and analyze the existing mosaic of management across selected ecosystems in the southern portion of the State. Visual and statistical results indicate significant gaps in the management framework of southern Florida that, if filled, could achieve a greater level of consistency and more complete coverage of ecosystem management policies. Based on the spatial distribution of 58 ecosystem management indicators, notable gaps persist in the southwest coast, southeast coast, and central Everglades ecosystems, particularly for wildlife corridors and collaboration with neighboring jurisdictions. We also test for spatial autocorrelation of ecosystem planning scores and find that local jurisdictions with strong ecosystem management capabilities tend to cluster within specific ecosystems. Based on the findings, we make recommendations on how and where local plans can be strengthened to more effectively attain the objectives of ecosystem approaches to management.     

Fuzzy assessment of land suitability for scientific research reserves

Evaluating the characteristics of a set of sites as potential scientific research reserves is an example of land suitability assessment. Suitability in this case is based upon multiple criteria, many of which can be linguistically imprecise and often incompatible. Fuzzy logic is a useful method for characterizing imprecise suitability criteria and for combining criteria into an overall suitability rating. The Ecosystem Management Decision Support software combined a fuzzy logic knowledge base we developed to represent the assessment problem with a GIS database providing site-specific data for the assessment. Assessment of sites as a potential natural reserve for the new University of California campus at Merced demonstrates the benefits of fuzzy suitability assessment. The study was conducted in three stages of successively smaller assessment regions with increasingly fine spatial resolution and specificity of criteria. Several sites were identified that best satisfy the suitability criteria for a reserve to represent vernal pool habitat.