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101.
Ensuring that new buildings do not interfere with the recreational and protective functions of the natural system and that the buildings will be useful long enough to protect the investment are among long-term solutions to coastal erosion. We propose that coastal cliff management districts be established for management of eroding high relief shorelines. Such districts would include an imminent failure zone, in which bluff retreat is possible at any time; a migration zone, which allows for long-term shoreline retreat; and a stability control zone in which activities affecting bluff erosion are restricted. Procedures are described for delineating these zones based on geomorphic criteria. If these land use controls are implemented, some shorefront development can be accommodated while retaining valuable characteristics of the natural system. 相似文献
102.
A land suitability model was developed to provide the planner with a quantitative tool for assessing the environmental limitations on proposed land-use changes in the area surrounding Lake Monroe in southern Indiana. The model incorporates a weighting procedure that allows the environmental evaluation of a decision to convert the present land use to another category. The data base for the model was assembled by a multidisciplinary team. A case study is included, which illustrates the advantages and limitations of the land suitability model as it is applied to the evaluation of a site for the Alumni Family Camp. 相似文献
103.
104.
Edwin T. Engmun 《Journal of the American Water Resources Association》1974,10(3):512-521
ABSTRACT: According to a concept known as partial area hydrology, watershed areas are separated into hydrologically active and passive subareas. The literature relating to the development of the partial area concept is reviewed briefly and the relationship of partial area hydrology to geology, soils, and micrometeorology is illustrated. The potential application of partial area hydrology is discussed with respect to present hydrologic techniques, future hydrologic models, urban hydrology, water quality, and water management. Suggestions for identifying and delineating the contributing areas are discussed. 相似文献
105.
This paper sheds light on changing farmers' land management practices in two mountain watersheds, with and without external
assistance, in the western hills of Nepal. Information used in the analysis were obtained through a survey of 300 households,
group discussion, key informant interviews, and field observation conducted during April–September 1999. Confronted with ever-decreasing
landholding size due to a steadily growing population and scarcity of nonfarming employment opportunities, farmers in both
watersheds have increasingly adopted assorted types of structural and biological measures to control soil erosion, landslides,
gully expansion, and soil nutrient loss to maintain or even enhance land productivity. Adoption of gully control measures,
construction of the retention walls, alley cropping, use of vegetative measures for landslide control, mulching, and use of
green manure and chemical fertilizers are found significantly high in the project area due to the provision of technical and
financial support, whereas composting is found significantly high in the nonproject area. Different from the traditionally
held beliefs, population pressure on a finite land resource has brought positive change in land management. However, the experience
from both watersheds indicates that there is limit to the extent that resource poor farmers can respond to land degradation
without any external assistance. Required is the arrangement for appropriate polices and support services and facilities enabling
farmers to adopt locationally suitable and economically attractive land management technologies. 相似文献
106.
Recent wetland area trends were estimated from the National Resources Inventory (NRI) for nonfederal rural lands for the period
1982–1987. NRI-based estimates of wetland area for states comprising the conterminous United States were highly correlated
with estimates made by the US Fish and Wildlife Service and with estimates of coastal salt marsh wetlands made by the National
Oceanic and Atmospheric Administration. Net wetland area declined by 1.1% (≈363,200 ha) during the five-year study period.
Conversion to open water, primarily caused by natural flooding in western inland basins, was responsible for altering extensive
wetland areas (≈171,400 ha). Of the human-induced wetland conversions, urban and built-up land was responsible for 48% of
the wetland loss, while agricultural development was indicated in 37% of the converted wetland area. A decrease in rural land,
and increases in both population, and urban and built-up land were associated with wetland loss among states. Potential reasons
for wetland loss were different in 20 coastal states than in 28 inland states. Proportionately, wetland loss due to development
was three times greater in coastal states than inland states, while agriculturally induced wetland losses were similar in
both groups. The proportionate declines of forested vs nonforested wetlands were not significantly different among states. 相似文献
107.
Owen P. Graham 《Environmental management》1992,16(2):205-223
A survey of land degradation was undertaken in New South Wales, Australia during 1987–1988. The aims of the survey were to
assess the location, extent, and severity of ten forms of degradation and to present the data in map and statistical form.
Sample points were located on a regular grid. The method was designed so that data could be acquired from aerial photographs,
expert local knowledge, and limited field checking. Individual statewide maps were prepared for each form of degradation.
Map data were shown in pixel form. Sheet and rill erosion and soil structure decline were confined mostly to lands used for
cropping. Gully erosion was commonly found across the state, while mass movement was confined to steeper lands. There were
three severe areas of dryland salinity; irrigation salinity was mapped in parts of the southern irrigation lands. Induced
soil acidity was severe in some cropping and pasture lands. Absence of tree regrowth was a noticeable feature of lands used
for cropping. The survey enabled community awareness of the problems of land degradation to be increased, in addition to assisting
regional land managers in resource allocation. The survey also provided the basis for the future location of sites that could
be used to monitor the trends in the status of land degradation. 相似文献
108.
The land evaluation and site assessment (LESA) method has been used extensively in the United States to assess agricultural
land suitability for different localities. Despite widespread use, LESA models rarely have been evaluated in a systematic,
comprehensive manner. This article discusses development of a LESA system for Hawaii, the first statewide application of the
LESA methodology. The empirical model was implemented with a computerized geographic information system (GIS). The system's
efficiency, ability to discriminate among land parcels, and robustness to subjective model parameter values are evaluated
with statistical analyses and map overlays of GIS data. Results show great potential to simplify the original model specification,
primarily through deletion of marginal site assessment factors. System output was generally insensitive to the numeric values
selected for model parameters, with exception of the ratio used to combine the land evaluation (LE) and site assessment (SA)
component scores. Relative supplies of the differing land attributes measured by the two components must be considered in
determining an appropriate LE:SA ratio for a given area. 相似文献
109.
Agricultural land evaluation and site assessment in the United States: An introduction 总被引:2,自引:0,他引:2
Frederick Steiner 《Environmental management》1987,11(3):375-377
The US Soil Conservation Service has developed an agricultural land evaluation and site assessment (LESA) system. The LESA system is being used by the US Department of Agriculture and other federal agencies to implement the Farmland Protection Policy Act of 1981. The LESA system and three case studies from the Pacific North-west are introduced in this article.Scientific Paper no. 7166, College of Agriculture and Home Economics Research Paper. Washington State University, Pullman, Washington. Project no. 0010. 相似文献
110.
Pierre Walther 《Environmental management》1987,11(4):439-446
Integrated resource management (IRM) is currently implemented in many parts of the world. This article promotes a pragmatic interpretation and suggests that idealistic beliefs in the problem-solving capacities of IRM are not justified. Successful implementation and performance of IRM are primarily a function of the historical context into which a project is placed. A comparative analysis of several case studies in Western Canada provides evidence for this argument, and the results can be summarized in a conceptual model about integration in resource management. IRM is interpreted as a process of constructing an objective reality of integration for sectorial management decisions, and this construction involves the transformations of power structures. This article suggests several pragmatic conclusions for IRM practice. 相似文献