首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The fisheries of Lake Victoria have undergone a major transformation over the last three decades. The character of the lake has been subject to the influence of many powerful factors including: substantial increases in fishing effort; growing integration into the global fish market; acceleration of anthropogenic activities in the catchment area; demographic change; the influence of adverse shifts in the climate; and introduction of exotic plant and animal species. The task of managing the lake's resources, therefore, has never been more daunting. This article argues that, in most cases, the authorities charged with achieving the goal of sustainable development for the fishery, have failed to address the symptoms—let alone the origins—of the current unsustainable tendencies embedded in the social, economic and political fabric of Lake Victoria's riparian States. It is these factors that directly impinge upon the success of management initiatives for the lake. The article argues that if sustainable development is to be achieved, then stakeholders must act in concert, eliminate unsustainable practices and reprogramme development plans to focus on realistic goals. A possible way forward will be to develop a participatory management system.  相似文献   

2.
Sensitivity indices, which rank factors pertinent to surface and subsurface runoff pathways, were used to identify phosphorus source areas in riparian zones of 15 northern Minnesota lakes. Watershed models were first developed using a geographic information system (GIS). Empirical models were then developed correlating water quality with land use, lake morphometry, and riparian sensitivity. Base models of forested, cultivated, pasture/open, wetland and residential land use within 100, 200, 400, and 2000 m of the study lakes were regressed on total phosphorus and chlorophyll-a. Area-weighted groundwater and surface runoff sensitivity indices were then incorporated into each model and tested for significance. Within the 200-m buffer, the total phosphorus base model was improved by including the groundwater index alone. The chlorophyll-a base model at 200 m was improved by including: (1) the groundwater index alone, and (2) both the groundwater and surface runoff sensitivity indices. Results suggest that surface and subsurface runoff analysis of potential source areas can improve decision making for lake riparian management.  相似文献   

3.
Water is strongly linked with the overall development framework of the Brahmaputra basin. However, the absence of integrated management of Brahmaputra water resources and lack of coordination among the riparian states constitutes an ongoing threat to future development plans within the basin. Brahmaputra's abundant hydropower potential can help give riparian countries a safer energy future that is the key driving force behind the prospect of potential cooperation. This paper analyses the current status of Brahmaputra water resources and identifies the perspectives of riparian countries regarding the development of the Brahmaputra basin. It also identifies the opportunities for cooperation and regional development through integrated water development and management of the Brahmaputra basin. It is essential to develop an integrated water resources management approach involving all riparians to foster regional development and overcome the prospect of severe water conflict along the Brahmaputra basin.  相似文献   

4.
Ecological regions are areas of similar climate, landform, soil, potential natural vegetation, hydrology, or other ecologically relevant variables. The makeup of aquatic biological assemblages (e.g., fish, macroinvertebrates, algae, riparian birds, etc.) varies dramatically over the landscape, as do the environmental stresses that affect the condition of those assemblages. Ecoregions delineate areas where similar assemblages are likely to occur and, therefore, where similar expectations can be established. For this reason, ecological regions have proven to be an important tool for use in the process of ecological assessment. This article describes four examples of the use of ecological regions in important aspects of environmental monitoring and assessment: (1) design of monitoring networks; (2) estimating expected conditions (criteria development); (3) reporting of results; (4) setting priorities for future monitoring and restoration. By delineating geographic areas with similar characteristics, ecological regions provide a framework for developing relevant indicators, setting expectations through the use of regional reference sites, establishing ecoregion-specific criteria and/or standards, presenting results, focusing models based on relationships between landscape and surface water metrics, and setting regional priorities for management and restoration. The Environmental Protection Agency and many state environmental departments currently use ecoregions to aid the development of environmental criteria, to illustrate current environmental condition, and to guide efforts to maintain and restore physical, chemical and biological integrity in lakes, streams, and rivers.  相似文献   

5.
ABSTRACT. Evaluation of lakes as they are related to groundwater flow systems is of special concern prior to efficient development and planning operations. Both naturally occurring and artificially created lakes are being developed rapidly as recreational and residential areas. Simultaneously, field verification of theoretical groundwater flow system behavior has progressed to the point where hydrogeologists trained to understand basic concepts of flow-system analysis can begin to broaden their research and service base, and to work closer with planners, developers, and engineers. It is suggested that particular efforts be directed toward a greater evaluation of physical, chemical, and biological aspects of potentially developable lake sites to aid in selecting use patterns in accord with these factors. Many lake developments are not in harmony with the physical environment. The resulting misuse of resources is often expressed as accelerated eutrophication of lakes, or by quality degradation of shallow groundwater flow systems contiguous to them. Lakes can no longer be considered as separate entities. Methodology for investigating the interchange of surface and near-surface water is adequate however, the application of known interchange relationships is inadequate. .  相似文献   

6.
ABSTRACT: Riparian zones perform a variety of biophysical functions that can be managed to reduce the effects of land use on instream habitat and water quality. However, the functions and human uses of riparian zones vary with biophysical factors such as landform, vegetation, and position along the stream continuum. These variations mean that “one size fits all” approaches to riparian management can be ineffective for reducing land use impacts. Thus riparian management planning at the watershed scale requires a framework that can consider spatial differences in riparian functions and human uses We describe a pilot riparian zone classification developed to provide such a framework for riparian management in two diverse river systems in the Waikato region of New Zealand. Ten classes of riparian zones were identified that differed sufficiently in their biophysical features to require different management. Generic “first steps” and “best practical” riparian management recommendations and associated costs were developed for each riparian class. The classification aims to not only improve our understanding of the effectiveness of riparian zone management as a watershed management tool among water managers and land owners, but to also provide a basis for deciding on management actions.  相似文献   

7.
The fisheries of Lake Victoria have reached a critical stage in their development: catches are declining, and there is increasing evidence of hardship amongst the fishing communities. In an effort to countermand the reduction in the flow of economic benefits the lake's riparian states are collaborating with international agencies to develop a fisheries management strategy that would be based on a partnership between stakeholders. One possible area for such collaboration is via the devolution of certain access controls to fishing communities. This paper describes findings from recent research and argues that notions of access are linked to community perceptions of the resource, control over it and their own individual and collective manoeuvrings designed to retain and improve livelihoods.  相似文献   

8.
ABSTRACT: Forest buffers adjacent to water bodies are widely prescribed in forest management to protect ecological functions of riparian systems. To date, buffers have been applied on the landscape uniformly without quantifying their effectiveness or the effects they have on landscape characteristics. Our objective was to quantify landscape characteristics (amount of edge and interior forest) when buffers were applied to water bodies in a 100 by 100 km area of northern Minnesota. We used a Landsat classified image in a geographic information system platform to apply two buffer widths ?28.5 m and 57 m — to water bodies, including nonforested wetlands, intermittent or perennial streams, and lakes. A total of 107,141 ha (18.3 percent) of the forest area was adjacent to and within 28.5 m of these water bodies, while 201,457 ha of forest was within 57 m, representing 34.4 percent of the total forest area. Imposing a 28.5 m buffer on water bodies increased the amount of edge and interior forest in the study area. When water bodies were buffered with a 57 m forest strip, we found a slight increase in forest edge from the current condition, and this buffer width resulted in the largest amount of interior forest. Interior forest increased with the 57 m buffer due to the density of water bodies in this region; adjacent water bodies coalesced when buffers were applied and formed isolated forest islands that contained forest interior habitat. Instead of wholesale application of set width riparian buffers, we suggest that ecological conditions of riparian areas be evaluated on a site level and that areas that currently provide important riparian conditions be maintained on the landscape with appropriate management practices.  相似文献   

9.
ABSTRACT: Results of a study to determine the relationship between physical characteristics of Adirondack lakes and variations in peak boat-use intensity indicated that 69 percent of the variation in peak use can be accounted for by the number of public and commercial boat-launching facilities per mile of lake shoreline. Other lake characteristics related to peak boat use were: the number of commercial overnight accommodations available, number of boat slips, lake size, and miles of lake shoreline. Lake characteristics not related to peak use were: accessibility, configuration, tent spaces available, surrounding landscape quality, volume of traffic and availability of other lakes. This information should provide recreation managers and planners with a better understanding of factors related to variation in peak boating-use periods.  相似文献   

10.
ABSTRACT: Growth in the commercial sector of the economy and the increased importance of total waste water volumes in design have created a need for methods of estimating commercial water demand. The results of a multiple correlation analysis and a principal components analysis suggest that commercial water demand is a function of the following three primary constructs: an employee water use factor, a customer layout factor, and a customer water facility factor. Three easily measured variables were used to represent these primary constructs: gross store area, length of display windows, and the number of drinking fountains, respectively. Prediction equations relating water use and the three variables were derived and can be used by planners in estimating commercial water use.  相似文献   

11.
Wetland boundary and land-use planning in southern Ontario,Canada   总被引:1,自引:0,他引:1  
There is a general lack of understanding of wetland processes and a general paucity of scientific research to predict the effects of development on wetland boundary. This paper presents the results of a survey of wetland managers as to how they delineate wetland boundaries, define compatible land uses, and restrict land uses adjacent to wetland boundaries. A major finding from the survey is that 75% of land-use planners and wetland managers failed to identify any compatible land use or restricted land use for development proposals that may affect provincially significant wetlands. The government agencies overwhelmingly lack adequate methodologies and/or criteria to delineate and protect wetland boundaries. The paper closes with a plea to consider dynamic hydrological factors in land-use planning.  相似文献   

12.
13.
/ Contemporary trends in natural resource management are reviewed, with specific reference to the shift in conservation management strategies away from law enforcement-based strategies towards strategies aimed at facilitating local community participation in the management of natural resources. This review lays a foundation for the presentation of a conceptual framework, the partnership forum framework, for the planning, implementation, and evaluationof protected area outreach programmes. The framework proposes that protected areas should function as integral components of the local social, economic, and environmental systems and that the integration of the protected area into these systems should be managed through comanagement institutions. The establishment of such institutions is discussed, and it is argued that the development of comanagement institutions can be characterized into four progressive phases: a preliminary communication phase, a problem-solving phase, a pilot project phase, and a comanagement phase. The framework proposes that during the three initial phases the partnership forum members will develop management procedures that they will use during the comanagement phase. The framework is presented as a design skeleton around which the site-specific characteristics of specific protected area outreach programs will combine to form an outreach program, i.e., the framework is process rather than project based.KEY WORDS: Sub-Saharan Africa; Integrated conservation and development  相似文献   

14.
ABSTRACT: Federal planners, in proposing the massive main stem Missouri River water developments in Montana and North Dakota, promised economic and social benefits to the local residents. Five main stem dams, Fort Peck, Garrison, Oahe, Big Bend and Fort Randall, were evaluated for community and rural development effectiveness. Thirty-seven development factors were examined and improvements noted. Only small differences were noted between areas with water developments and the control area. Further analysis revealed that water development benefits moved downstream and to existing urban areas. The Missouri River's rural areas and small communities were not developed significantly by the water projects. Several problems associated with water development policy were illustrated by the study. Cultural differences between planners and the population impacted were ignored. Second, the allocation of social costs was not considered and related to this, serious geographic maldistribution of benefits and costs resulted. The differences between pre-development promises and development performance was dramatic. While the large dams remain as landmarks to engineering prowess, the projects need to be evaluated for their success in meeting humanistic development objectives. Major redevelopment may be warranted by such an ex-post evaluation.  相似文献   

15.
Roughly 45% of the assessed lakes in the United States are impaired for one or more reasons. Eutrophication due to excess phosphorus loading is common in many impaired lakes. Various strategies are available to lake residents for addressing declining lake water quality, including septic system upgrades and establishing riparian buffers. This study examines 25 lakes to determine whether septic upgrades or riparian buffers are a more cost-effective strategy to meet a phosphorus reduction target. We find that riparian buffers are the more cost-effective strategy in every case but one. Large transaction costs associated with the negotiation and monitoring of riparian buffers, however, may be prohibiting lake residents from implementing the most cost-effective strategy. An erratum to this article is available at .  相似文献   

16.
ABSTRACT: Cattle grazing practices in the western United States have contributed to widespread riparian degradation resulting in unstable channel morphologies and the loss of fish habitat. Because of prolonged disturbance, numerous riparian areas on both public and private lands have been fenced to exclude cattle in order to promote vegetation establishment and riparian improvement. We selected four gravel-bedded, steep alluvial streams in eastern Oregon with cattle exclosures greater than 14 years old for an analysis of geomorphic adjustments following the removal of cattle grazing. We compare channels inside exclosures and in adjacent grazed reaches to identify the salient stream channel properties that respond to the removal of riparian stresses and to document the magnitude of these changes. Results indicate that significant changes occur, with reductions in bankfull dimensions and increases in pool area being the most common and identifiable changes. At all four sites, bankfull widths are narrower by 10 to 20 percent, and the percentage of channel area occupied by pools is higher in the exclosure by 8 to 15 percent. The increase in pool area is primarily offset by a reduction in the percent glide area. Not all of the channel properties demonstrate adjustment, indicating that perhaps 14 years is an insufficient duration for these variables to adjust.  相似文献   

17.
How Egypt and Ethiopia will defend or promote their interests in the Nile basin has recently become clearer. Egypt will again seek to create 'facts on the ground', this time a large new land reclamation and settlement scheme called the New Valley Project. Ethiopia too will create facts by proceeding with water resources development in the Blue Nile basin, including the construction of low-cost microdams. If Egypt and Ethiopia pursue these two unilateral initiatives, they may find themselves on a collision course that both may have difficulty changing. The challenge facing the Nile riparian countries is to find a balance between the upstream countries' support for the principle of 'equitable use', and Egypt's and Sudan's support for the principle of 'no appreciable harm'. Of all the riparian states, Egypt has the most to gain from the establishment of a basin-wide framework for water resources development. It can ill afford a future in which upstream riparians take unilateral action with respect to water development projects. If Egypt would reduce its existing water use by 5 billion m3 and scale back or abandon the plans for the New Valley Project, there would be enough water available to strike a deal that would bring Ethiopia and other upstream riparians into the framework of a comprehensive Nile Waters Agreement.  相似文献   

18.
ABSTRACT: In the environmental and agricultural conservation planning process, more efficient and effective tools are needed for planners to assist private landowners with making wiser land use decisions. Current methods are slow, inefficient, and costly. Scientific techniques have not been fully implemented within the planning process, yet such plans are increasingly needed to meet water quality and Total Maximum Daily Load (TMDL) requirements. The objectives of this study are to (a) utilize the web for accessing an integrated science‐based land use decision support system; (b) link decision tools, models, and databases to the user via the web; (c) link distributed models and databases for enhanced planning efficiency; and (d) integrate the above into an easily usable and readily accessible system. The procedures resulting in the initial design involved planning expertise and focus groups' input. The system was developed in partnership with the Natural Resources Conservation Service of the U.S. Department of Agriculture and several state agencies. A survey of 150 certified conservation planners, the end users, was conducted to identify the data sets and planning tools needed. Data, tools, and models then were selected and integrated into a web accessible system. Specifically, the first generation used a web interactive Geographic Information System (GIS) that overlaid onto digital orthoquads and/or soils polygons field boundaries, transportation, hydrologic features (such as drains, rivers, lakes, etc.), and high pesticide risk runoff or infiltration areas. Conservation planners found they could save time with the system. Clients could access the system quickly to help them prepare for meeting with their planner. Previously acquiring GIS maps in some cases had been a lengthy process that limited use of the information in land use decisions.  相似文献   

19.
This paper addresses questions of affective responses of residents of rural Arizona to changes in proximate community and riparian landscapes and the congruence of their perceptions of change with physical measures of change in those landscapes. Based on findings and concepts from previous studies, perceptions of change were assessed using a mail survey. Physical measures of land use and vegetation change were obtained from aerial photography for two points in time spanning approximately 13 years and were analyzed using a geographic information system. Significant differences were found in perceptions of change in the community and riparian landscapes. In contrast with previous findings, a majority of respondents found the changes as either improving or having no effect on landscape quality. Those who were more frequent users of the riparian landscape tended to be more aware of changes in it. The findings also suggest challenges for planners and resource managers working in rural areas adjacent to riparian landscapes.  相似文献   

20.
The European Union Water Framework Directive (WFD) requires Member States to set water quality objectives and identify cost-effective mitigation measures to achieve "good status" in all waters. However, costs and effectiveness of measures vary both within and between catchments, depending on factors such as land use and topography. The aim of this study was to develop a cost-effectiveness analysis framework for integrating estimates of phosphorus (P) losses from land-based sources, potential abatement using riparian buffers, and the economic implications of buffers. Estimates of field-by-field P exports and routing were based on crop risk and field slope classes. Buffer P trapping efficiencies were based on literature metadata analysis. Costs of placing buffers were based on foregone farm gross margins. An integrated optimization model of cost minimization was developed and solved for different P reduction targets to the Rescobie Loch catchment in eastern Scotland. A target mean annual P load reduction of 376 kg to the loch to achieve good status was identified. Assuming all the riparian fields initially have the 2-m buffer strip required by the General Binding Rules (part of the WFD in Scotland), the model gave good predictions of P loads (345-481 kg P). The modeling results show that riparian buffers alone cannot achieve the required P load reduction (up to 54% P can be removed). In the medium P input scenario, average costs vary from £38 to £176 kg P at 10% and 54% P reduction, respectively. The framework demonstrates a useful tool for exploring cost-effective targeting of environmental measures.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号