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1.
Land use change in California,USA: Nonpoint source water quality impacts   总被引:2,自引:0,他引:2  
California’s population increased 25% between 1980 and 1990, resulting in rapid and extensive urbanization. Of a total 123,000 ha urbanized in 42 of the state’s 58 counties between 1984 and 1990, an estimated 13% occurred on irrigated prime farmland, and 48% on wildlands or fallow marginal farmlands. Sixty-six percent of all new irrigated farmland put into production between 1984 and 1990 was of lesser quality than the prime farmland taken out of production by urbanization. Factors dictating the agricultural development of marginal farmlands include the availability and price of water and land, agricultural commodity prices, and technical innovations such as drip irrigation systems that impact the feasibility and costs of production. The increasing amount of marginal farmland being put into production could have significant water quality consequences because marginal lands are generally steeper, have more erodible soils, poorer drainage, and require more fertilizer than prime farmlands. Although no data exist to test our hypothesis, and numerous variables preclude definitive predictions, the evidence suggests that new irrigated marginal lands can increase nonpoint source (NPS) pollution for a given size area by an order of magnitude in some cases.  相似文献   

2.
Abstract

In this study, the wind energy potential of Elazig is statistically analyzed based on hourly measured wind speed data over the five-year period from 1998 to 2002. The probability density distributions are derived from cumulative distribution functions. Two probability density functions are fitted to the measured probability distribution on a yearly basis. The wind energy potential of the location is studied based on the Weibull and Rayleigh distributions. It was found that the numerical values of both Weibull parameters (k and c) for Elazig vary over a wide range. The yearly values of k range from 1.653 to 1.878 with an average value of 1.819, while those of c are in the range of 2.757–2.994 m/s with an average value of 2.824 m/s. In addition, yearly mean wind speed and mean power density of Elazig is found as 2.79 m/s and 38.76 W/m2, respectively. The wind speed distributions are represented by Weibull distribution and also by Rayleigh distribution, with a special case of the Weibull distribution for k = 2. As a result, the Rayleigh distribution is found to be suitable to represent the actual probability of wind speed data for Elazig.  相似文献   

3.
4.
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.  相似文献   

5.
The ability of Section 404 of the Clean Water Act to act as an effective, efficient, and equitable land-use planning tool was assessed through a survey of Section 404 permits in Wisconsin. In a six-month period of permitting, the 404 program reduced wetland losses in the state by 15%. Several factors were examined that may affect permit decisions; these factors are water dependency, alternatives, project type, wetland type, and public or agency comments. Only the water dependency of the project had a statistically significant effect on permit decisions, although development projects that were perceived to provide public good were more likely to be permitted. Environmental impacts of a proposed fill project were not adequately assessed in any of the permit decisions. Because of the way Section 404 is interpreted and administered by the US Army Corps of Engineers, increasing net benefits and achieving an equitable distribution of those benefits is difficult. The corps does not perform any functional evaluations of wetlands nor do they attempt to measure economic value and environmental impacts. In addition, the 404 review process is, in effect, inaccessible to the public. The de facto interpretations of the Section 404 regulations and a lack of program funding and trained personnel all contribute to the program's ineffectiveness.  相似文献   

6.
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.  相似文献   

7.
/ Management of ecosystems has advanced by an improvement in our understanding not only of how ecosystems function, but of how people perceive their functioning and what they consider to be environmental problems within those systems. Central to such management is understanding how people view estuaries. In this article I explore the perceptions and attitudes of people about coastal recreation, environmental problems, and future land use along the New Jersey shore (USA) by interviewing people who attended a duck decoy and craft show on Barnegat Bay. The people who were interviewed engaged in more days of fishing than any other recreational activity and engaged in camping the least. There were significant differences in recreational rates as a function of gender and location of residence, with men hunting and fishing more than women and photographing less than women. Jet skis were perceived as the most severe environmental problem, with chemical pollution, junk, oil runoff and overfishing as second level problems. Birds were perceived as not an environmental problem at all. Fishing, hiking, preservation, and camping ranked as the highest preferred future land uses for the two sites examined (Oyster Creek Nuclear Generating Station, Naval Weapons Station Earle). The preferred future land uses for these two sites, which are not under consideration for land-use changes, were very similar to those of people living near the Department of Energy's Savannah River Site in South Carolina, despite the media attention and considerations of nuclear storage.KEY WORDS: Recreation; Perceptions; Environmental problem; Gender; Land use; Coastal  相似文献   

8.
The Ala Wai Canal Watershed Model (ALAWAT) is a planning-level watershed model for approximating direct runoff, streamflow, sediment loads, and loads for up to five pollutants. ALAWAT uses raster GIS data layers including land use, SCS soil hydrologic groups, annual rainfall, and subwatershed delineations as direct model parameter inputs and can use daily total rainfall from up to ten rain gauges and streamflow from up to ten stream gauges. ALAWAT uses a daily time step and can simulate flows for up to ten-year periods and for up to 50 subwatersheds. Pollutant loads are approximated using a user-defined combination of rating curve relationships, mean event concentrations, and loading/washoff parameters for specific subwatersheds, land uses, and times of year. Using ALAWAT, annual average streamflow and baseflow relationships and urban suspended sediment loads were approximated for the Ala Wai Canal watershed (about 10,400 acres) on the island of Oahu, Hawaii. Annual average urban suspended sediments were approximated using two methods: mean event concentrations and pollutant loading and washoff. Parameters for the pollutant loading and washoff method were then modified to simulate the effect of various street sweeping intervals on sediment loads.  相似文献   

9.
Land use since 1935 was quantified for Georgia, USA, and for a sample of 20 counties from the major physiographic regions within the state. Statistical data on crop production, pasture productivity, and forest growth were used to estimate net primary production. Appropriate harvest indices (ratio of crop yield to total plant production) were used to correct crop yield data for different decades. Net primary production (NPP) of the Georgia landscape increased from 2.5 to 6.4 tonnes/ha from 1935 to 1982, but varied considerably among land uses and physiographic regions. NPP in the piedmont and mountains reached a plateau between 1960 and 1982, but the upper and lower coastal plains showed a continued linear increase in NPP. In all regions, NPP rose most between 1960 and 1982, coinciding with increases in inputs such as fertilizer and irrigation. Natural ecosystem NPP for Georgia is approximately 16–18 tonnes/ha, and the estimated actual NPP is thus considerably less than the potential. Spatial and temporal patterns of NPP may be a useful basis for evaluating the biological performance of a landscape.  相似文献   

10.
Fourteen streams in the Sierra Nevada in the USA were sampled to determine whether diversions of streamflow for hydroelectric development had caused significant changes in riparian vegetation. Several streams showed significant differences in vegetation cover, community composition, or community structure between pairs of diverted and undiverted reaches. On some streams, environmental conditions rather than streamflow diversions may have been responsible for vegetation differences. Streams in the Sierra Nevada respond individualistically to diversions. Prediction of vegetation responses must take into consideration environmental characteristics of specific stream reaches.  相似文献   

11.
This study investigates the wind and solar electricity generation availability at the Solar Energy Institute of Ege University, Izmir, Turkey. The main purpose of this study is to design an appropriate wind-PV hybrid system to cover the electricity consumption of the Institute. In order to do this, monthly average solar irradiation and wind speed data are used, which were measured, consisting of hourly records over an eight-year period from 1995–2002. Simple models were developed to determine wind, solar, and hybrid power resources per unit area. Correlations between the solar and wind power data were carried out on an hourly, daily, and monthly basis. It is shown that the hybrid system can be applied for the efficient and economic utilization of these resources.  相似文献   

12.
This paper describes the methods used to evaluate the potential for achieving sustainable energy development in six Chinese villages included in the Sustainable Users' Concepts for China Engaging Scientific Scenarios (SUCCESS) Project by examining energy efficiency potential and local renewable energy prospects. The approaches needed to obtain and analyse information on possible energy efficiency measures and renewable energy resources are summarised. Results are presented in terms of cumulative net savings in primary energy consumption, as an indicator of energy resource depletion, and associated carbon dioxide emissions, as an indicator of global climate change. Options for sustainable energy development are ranked in order of likely implementation and practical actions which could be considered in each village are identified.  相似文献   

13.
This article summarizes some of the results from the application of the indicators for sustainable energy development (ISED) tool for analyzing Lithuania's energy sector, in terms of trends, setting energy policy goals and monitoring progress towards these goals. This experience illustrates the potential applicability of the ISED methodology for energy policy development in economies in transition, using Lithuania as an example. The article presents a summary of the results achieved and conclusions arrived at from the analysis of six priority areas in the context of the research project coordinated by the International Atomic Energy Agency, and provides recommendations for the development of sustainable energy policy using the ISED approach.  相似文献   

14.
Ecological planning proposal for Kruger National Park   总被引:1,自引:0,他引:1  
This article discusses an application of the ecological planning model proposed by Van Riet and Cooks. The various steps outlined in this model have been applied to Kruger National Park in South Africa. The natural features of Kruger National Park, which form the basis of such an ecological planning exercise and from which the various land use categories, values, and zoning classes can be determined, are discussed in detail. The suitability of each of the various features is analyzed and a final zoning proposal for Kruger National Park is suggested. Furthermore a method for selecting a site for a new camp is illustrated by referring to the site for the new Mopane rest camp which is now under construction in the Kruger National Park. The conclusion is reached that the proposed ecological planning model can be used successfully in planning conservation areas such as Kruger National Park and for the selection of the most desirable sites for the establishment of new rest camps. Its suitability as a practical model in such planning exercises is proven by the fact that the siting proposals of two new camps based on this model have been accepted by the National Parks Board, the controlling body of Kruger National Park.  相似文献   

15.
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   

16.
The Economic Value of Open Space: A Review and Synthesis   总被引:3,自引:0,他引:3  
/ Communities increasingly face development pressures that can irreversibly alter open space lands. While the monetary costs and benefits of development are typically known, the corresponding values of natural lands are complex and difficult to measure. This paper reviews different concepts of economic value in relation to open space, describes methods for quantifying these values, and presents examples of each from published literature. Open space benefits accruing to citizens as market values or consumers' surplus include market and enhancement values, production values, natural systems value, use and nonuse values, and various intangible values. Economic impacts that open space lands have on local communities and economies include fiscal impacts on municipal budgets, expenditures from open space-related activities, and impacts from employment and tax revenues. These values are not universally present within a given community, nor are they quantitatively additive. However, a comprehensive consideration of the multiple values of open space will better inform community decisions about land conservation and development. KEY WORDS: Conservation; Economic value; Land use; Open space; Zoning  相似文献   

17.
Lakeshore development in Vilas County, northern Wisconsin (USA) is heterogeneous, ranging from lakes that are surrounded by homes and commercial establishments to lakes that have no buildings on their shorelines. Development in this recreational area has increased, and since the 1960s over half of new homes have been built on the lakeshore. We examined building density around lakes in relationship to 11 variables, including in-lake, shoreline, and social characteristics. Buildings in many parts of northern Wisconsin tend to be concentrated around shorelines; in Vilas County 61% of all medium-sized buildings (our proxy for residential development) on private land were ≤100 m of a lake. The probability of development on a lake was largely related to lake surface area, with larger, more accessible lakes showing a higher probability of development. Building density along shorelines varied with travel cost, lake surface area, presence of wetlands, and extent of public land ownership. Building density was greater on larger, more accessible lakes that were surrounded by forest (as opposed to wetlands) and public lands. Gaining a more precise understanding of human settlement patterns can help direct planning and resource protection efforts to lakes most likely to experience future development.  相似文献   

18.
In the last three decades the Nigerian environment has experienced rapid degradation. A major contributory factor of this phenomenon is the pattern of socioeconomic development in the country that gives little or no consideration to environmental outcomes. An aspect of this development is the economic policy of removal of subsidies on petroleum products initiated in 1986 as a result of the worsening economic situation in the country which begun in the early 1980s. The result of this is that prices of commercial fuels inclusive of kerosene and LPG (cooking gas) have continued to rise beyond the reach of majority of the Nigerian population. The paper examines the effect of increasing prices of petroleum-derived energy sources on the pattern of energy use for cooking in low and middle-income households and the environmental implication in Ibadan, the largest truly indigenous urban centre in sub-Saharan Africa. Results show that prior to the further subsidy removal of 1993, majority of households sampled used kerosene for cooking. Thereafter, a complete or partial switch in the pattern of domestic energy consumption ensued with more households using fuel wood and other more polluting and less efficient energy sources for cooking. The paper recommends a transition towards more environmental friendly energy sources for household use.  相似文献   

19.
This article examines energy priorities for Thailand from the economic, social and environmental perspectives of sustainable development. The article uses a set of indicators devised by the International Atomic Energy Agency in partnership with other international agencies and research institutes in seven countries. Thailand's energy efficiency in the 1980s and 1990s are analysed using energy intensity indicators, and possible impacts on sustainable energy development are highlighted. The early 1990s in particular was an important period for Thailand, as the country was at the height of its economic growth, and a number of energy efficiency and conservation programmes were launched. Energy intensity indicators show continuing and faster growth in energy consumption relative to economic activity. The financial crisis in the late 1990s did halt growth in energy consumption, with positive consequences on environmental emissions, but only temporarily as Thailand's economy quickly started to recover in 2000. Notwithstanding the financial crisis, the other indicators show significant progress in economic and social dimensions.  相似文献   

20.
We examined the relationship between water quality and fish communities within two agricultural areas using a computer simulation model. Our analyses focused on a coolwater stream, Wells Creek in southeastern Minnesota, and a warmwater stream, the Chippewa River in western Minnesota. We used the Agricultural Drainage and Pesticide Transport (ADAPT) model in relation to land use to calculate instream suspended sediment concentrations using estimates of sediment delivery, runoff, baseflow and streambank erosion, and quantified the effects of suspended sediment exposure on fish communities. We predicted the effects of agricultural practices on stream fish communities under several possible land use scenarios, with reference to current conditions. Land use changes led to reductions in sediment loading of up to 84% in Wells Creek and 49% in the Chippewa River. The reduction in sediment loading across scenarios may be directly related to a reduction in runoff by about 35% in both study areas. We found a 98% decrease in lethal concentrations of suspended sediment on fish in Wells Creek with an increase in conservation tillage, riparian buffers, and permanent vegetative cover. However, the effects of suspended sediment did not significantly decrease in the Chippewa River. This difference between study areas was likely due to differences in tolerance to suspended sediment between coolwater and warmwater fish communities and differences in topography, runoff and bank erosion between the two streams. The Minnesota Cooperative Fish and Wildlife Research Unit is jointly sponsored by the US Geological Survey, the University of Minnesota, the Minnesota Department of Natural Resources, and the Wildlife Management Institute.  相似文献   

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