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1.
Modeling the relationship between land use and surface water quality   总被引:47,自引:0,他引:47  
It is widely known that watershed hydrology is dependent on many factors, including land use, climate, and soil conditions. But the relative impacts of different types of land use on the surface water are yet to be ascertained and quantified. This research attempted to use a comprehensive approach to examine the hydrologic effects of land use at both a regional and a local scale. Statistical and spatial analyses were employed to examine the statistical and spatial relationships of land use and the flow and water quality in receiving waters on a regional scale in the State of Ohio. Besides, a widely accepted watershed-based water quality assessment tool, the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS), was adopted to model the plausible effects of land use on water quality in a local watershed in the East Fork Little Miami River Basin. The results from the statistical analyses revealed that there was a significant relationship between land use and in-stream water quality, especially for nitrogen, phosphorus and Fecal coliform. The geographic information systems (GIS) spatial analyses identified the watersheds that have high levels of contaminants and percentages of agricultural and urban lands. Furthermore, the hydrologic and water quality modeling showed that agricultural and impervious urban lands produced a much higher level of nitrogen and phosphorus than other land surfaces. From this research, it seems that the approach adopted in this study is comprehensive, covering both the regional and local scales. It also reveals that BASINS is a very useful and reliable tool, capable of characterizing the flow and water quality conditions for the study area under different watershed scales. With little modification, these models should be able to adapt to other watersheds or to simulate other contaminants. They also can be used to study the plausible impacts of global environmental change. In addition, the information on the hydrologic effects of land use is very useful. It can provide guidelines not only for resource managers in restoring our aquatic ecosystems, but also for local planners in devising viable and ecologically-sound watershed development plans, as well as for policy makers in evaluating alternate land management decisions.  相似文献
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Land-use change, dominated by an increase in urban/impervious areas, has a significant impact on water resources. This includes impacts on nonpoint source (NPS) pollution, which is the leading cause of degraded water quality in the United States. Traditional hydrologic models focus on estimating peak discharges and NPS pollution from high-magnitude, episodic storms and successfully address short-term, local-scale surface water management issues. However, runoff from small, low-frequency storms dominates long-term hydrologic impacts, and existing hydrologic models are usually of limited use in assessing the long-term impacts of land-use change. A long-term hydrologic impact assessment (L-THIA) model has been developed using the curve number (CN) method. Long-term climatic records are used in combination with soils and land-use information to calculate average annual runoff and NPS pollution at a watershed scale. The model is linked to a geographic information system (GIS) for convenient generation and management of model input and output data, and advanced visualization of model results. The L-THIA/NPS GIS model was applied to the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana, USA. Historical land-use scenarios for 1973, 1984, and 1991 were analyzed to track land-use change in the watershed and to assess impacts on annual average runoff and NPS pollution from the watershed and its five subbasins. For the entire watershed between 1973 and 1991, an 18% increase in urban or impervious areas resulted in an estimated 80% increase in annual average runoff volume and estimated increases of more than 50% in annual average loads for lead, copper, and zinc. Estimated nutrient (nitrogen and phosphorus) loads decreased by 15% mainly because of loss of agricultural areas. The L-THIA/NPS GIS model is a powerful tool for identifying environmentally sensitive areas in terms of NPS pollution potential and for evaluating alternative land use scenarios for NPS pollution management.  相似文献
4.
新疆玛纳斯河流域的土地利用与退化问题   总被引:12,自引:1,他引:11  
玛纳斯河流域山地、平原、沙漠、湖泊俱全,土地利用类型有8个一级类型及40个二级类。20世纪50年代以来,在山前水、土、光热组合优良地区开展大规模水土开发建设,使区内的土地资源得以充分利用,土地开发利用率达40%以上。然而,不合理的土地利用已经导致土地退化,其主要类型有土地荒漠化、耕地土壤贫瘠化、土壤次生盐渍化、土地沙漠化、水土流失、土地污染等6种。据区域土地利用特点与退化类型及原因,提出了合理利用土地与防止土地退化的5条措施,以确保玛河流域土地永续利用与持续发展。  相似文献
5.
Establishing aquatic restoration priorities using a watershed approach   总被引:10,自引:0,他引:10  
Since the passage of the Clean Water Act in 1972, the United States has made great strides to reduce the threats to its rivers, lakes, and wetlands from pollution. However, despite our obvious successes, nearly half of the nation's surface water resources remain incapable of supporting basic aquatic values or maintaining water quality adequate for recreational swimming. The Clean Water Act established a significant federal presence in water quality regulation by controlling point and non-point sources of pollution. Point-sources of pollution were the major emphasis of the Act, but Section 208 specifically addressed non-point sources of pollution and designated silviculture and livestock grazing as sources of non-point pollution. Non-point source pollutants include runoff from agriculture, municipalities, timber harvesting, mining, and livestock grazing. Non-point source pollution now accounts for more than half of the United States water quality impairments. To successfully improve water quality, restoration practitioners must start with an understanding of what ecosystem processes are operating in the watershed and how they have been affected by outside variables. A watershed-based analysis template developed in the Pacific Northwest can be a valuable aid in developing that level of understanding. The watershed analysis technique identifies four ecosystem scales useful to identify stream restoration priorities: region, basin, watershed, and site. The watershed analysis technique is based on a set of technically rigorous and defensible procedures designed to provide information on what processes are active at the watershed scale, how those processes are distributed in time and space. They help describe what the current upland and riparian conditions of the watershed are and how these conditions in turn influence aquatic habitat and other beneficial uses. The analysis is organized as a set of six steps that direct an interdisciplinary team of specialists to examine the biotic and abiotic processes influencing aquatic habitat and species abundance. This process helps develop an understanding of the watershed within the context of the larger ecosystem. The understanding gained can then be used to identify and prioritize aquatic restoration activities at the appropriate temporal and spatial scale. The watershed approach prevents relying solely on site-level information, a common problem with historic restoration efforts. When the watershed analysis process was used in the Whitefish Mountains of northwest Montana, natural resource professionals were able to determine the dominant habitat forming processes important for native fishes and use that information to prioritize, plan, and implement the appropriate restoration activities at the watershed scale. Despite considerable investments of time and resources needed to complete an analysis at the watershed scale, the results can prevent the misdiagnosis of aquatic problems and help ensure that the objectives of aquatic restoration will be met.  相似文献
6.
Understanding the environmental consequences of changing water regimes is a daunting challenge for both resource managers and ecologists. Balancing human demands for fresh water with the needs of the environment for water in appropriate amounts and at the appropriate times are shaping the ways by which this natural resource will be used in the future. Based on past decisions that have rendered many freshwater resources unsuitable for use, we argue that river systems have a fundamental need for appropriate amounts and timing of water to maintain their biophysical integrity. Biophysical integrity is fundamental for the formulation of future sustainable management strategies. This article addresses three basic ecological principles driving the biogeochemical cycle of nitrogen in river systems. These are (1) how the mode of nitrogen delivery affects river ecosystem functioning, (2) how increasing contact between water and soil or sediment increases nitrogen retention and processing, and (3) the role of floods and droughts as important natural events that strongly influence pathways of nitrogen cycling in fluvial systems. New challenges related to the cumulative impact of water regime change, the scale of appraisal of these impacts, and the determination of the impacts due to natural and human changes are discussed. It is suggested that cost of long-term and long-distance cumulative impacts of hydrological changes should be evaluated against short-term economic benefits to determine the real environmental costs.  相似文献
7.
The scientific research literature is reviewed (i) for evidence of how much reduction in nonpoint source pollution can be achieved by installing buffers on crop land, (ii) to summarize important factors that can affect this response, and (iii) to identify remaining major information gaps that limit our ability to make probable estimates. This review is intended to clarify the current scientific foundation of the USDA and similar buffer programs designed in part for water pollution abatement and to highlight important research needs. At this time, research reports are lacking that quantify a change in pollutant amounts (concentration and/or load) in streams or lakes in response to converting portions of cropped land to buffers. Most evidence that such a change should occur is indirect, coming from site-scale studies of individual functions of buffers that act to retain pollutants from runoff: (1) reduce surface runoff from fields, (2) filter surface runoff from fields, (3) filter groundwater runoff from fields, (4) reduce bank erosion, and (5) filter stream water. The term filter is used here to encompass the range of specific processes that act to reduce pollutant amounts in runoff flow. A consensus of experimental research on functions of buffers clearly shows that they can substantially limit sediment runoff from fields, retain sediment and sediment-bound pollutants from surface runoff, and remove nitrate N from groundwater runoff. Less certain is the magnitude of these functions compared to the cultivated crop condition that buffers would replace within the context of buffer installation programs. Other evidence suggests that buffer installation can substantially reduce bank erosion sources of sediment under certain circumstances. Studies have yet to address the degree to which buffer installation can enhance channel processes that remove pollutants from stream flow. Mathematical models offer an alternative way to develop estimates for water quality changes in response to buffer installation. Numerous site conditions and buffer design factors have been identified that can determine the magnitude of each buffer function. Accurate models must be able to account for and integrate these functions and factors over whole watersheds. At this time, only pollutant runoff and surface filtration functions have been modeled to this extent. Capability is increasing as research data is produced, models become more comprehensive, and new techniques provide means to describe variable conditions across watersheds. A great deal of professional judgment is still required to extrapolate current knowledge of buffer functions into broadly accurate estimates of water pollution abatement in response to buffer installation on crop land. Much important research remains to be done to improve this capability. The greatest need is to produce direct quantitative evidence of this response. Such data would confirm the hypothesis and enable direct testing of watershed-scale prediction models as they become available. Further study of individual pollution control functions is also needed, particularly to generate comparative evidence for how much they can be manipulated through buffer installation and management.  相似文献
8.
Since its introduction in the early 1960s, the EU Common Agricultural Policy (CAP) has demonstrated a capacity to adapt and change in the face of new challenges. The reformed CAP, under AGENDA 2000, encourages more environmentally friendly farming practices. In the context of their rural development plans, Member States are required to link policies on agriculture with protection of the environment and to ensure that farmers meet environmental standards. Additionally, Member States should maintain and restore the quality of both their aquatic and adjacent terrestrial ecosystems according to the Directive 2000/60/EU, 'Establishing a framework for Community Action in the field of Water Policy'. Within this framework, agri-environmental indicators play an important role in planning and implementing CAP guidelines. However, selection and use of the proper indicators remains unresolved, considering that ecosystem processes are complex and interactions in most cases not obvious. This paper proposes a methodology for assessing the environmental state and impacts of current land use and management when implementing agri-environmental measures of CAP. The proposed methodology includes a modified Driving forces-Pressures-Impacts-Responses (DPSIR) framework, identification of Zones of Specific Functional Interest (ZSFI), and criteria for selecting agri-environmental indicators, which assess the functional performance of each zone and meet existing legislation. The Mygdonia Watershed (Greece) is an example where through use of both the appropriate Minimum Data Set of agri-environmental indicators at the identified zones and the proposed modified DPSIR, the functioning performance of each ZSFI can be assessed to evaluate the applied agri-environmental measures.  相似文献
9.
The scientific research literature is reviewed (i) for evidence of how much reduction in nonpoint source pollution can be achieved by installing buffers on crop land, (ii) to summarize important factors that can affect this response, and (iii) to identify remaining major information gaps that limit our ability to make probable estimates. This review is intended to clarify the current scientific foundation of the USDA and similar buffer programs designed in part for water pollution abatement and to highlight important research needs. At this time, research reports are lacking that quantify a change in pollutant amounts (concentration and/or load) in streams or lakes in response to converting portions of cropped land to buffers. Most evidence that such a change should occur is indirect, coming from site-scale studies of individual functions of buffers that act to retain pollutants from runoff: (1) reduce surface runoff from fields, (2) filter surface runoff from fields, (3) filter groundwater runoff from fields, (4) reduce bank erosion, and (5) filter stream water. The term filter is used here to encompass the range of specific processes that act to reduce pollutant amounts in runoff flow. A consensus of experimental research on functions of buffers clearly shows that they can substantially limit sediment runoff from fields, retain sediment and sediment-bound pollutants from surface runoff, and remove nitrate N from groundwater runoff. Less certain is the magnitude of these functions compared to the cultivated crop condition that buffers would replace within the context of buffer installation programs. Other evidence suggests that buffer installation can substantially reduce bank erosion sources of sediment under certain circumstances. Studies have yet to address the degree to which buffer installation can enhance channel processes that remove pollutants from stream flow. Mathematical models offer an alternative way to develop estimates for water quality changes in response to buffer installation. Numerous site conditions and buffer design factors have been identified that can determine the magnitude of each buffer function. Accurate models must be able to account for and integrate these functions and factors over whole watersheds. At this time, only pollutant runoff and surface filtration functions have been modeled to this extent. Capability is increasing as research data is produced, models become more comprehensive, and new techniques provide means to describe variable conditions across watersheds. A great deal of professional judgment is still required to extrapolate current knowledge of buffer functions into broadly accurate estimates of water pollution abatement in response to buffer installation on crop land. Much important research remains to be done to improve this capability. The greatest need is to produce direct quantitative evidence of this response. Such data would confirm the hypothesis and enable direct testing of watershed-scale prediction models as they become available. Further study of individual pollution control functions is also needed, particularly to generate comparative evidence for how much they can be manipulated through buffer installation and management.  相似文献
10.
Nipped in the Bud: Why Regional Scale Adaptive Management Is Not Blooming   总被引:5,自引:2,他引:3  
Adaptive management is an approach to managing natural resources that emphasizes learning from the implementation of policies and strategies. Adaptive management appears to offer a solution to the management gridlock caused by increasing complexity and uncertainty. The concept of adaptive management has been embraced by natural resource managers worldwide, but there are relatively few published examples of adaptive management in use. In this article, we explore two watershed management projects in southeastern Australia to better understand the potential of adaptive management in regional scale programs through qualitative, case study–based investigation. The program logic of one case implies the use of passive adaptive management, whereas the second case claims to be based on active adaptive management. Data were created using participant observation, semistructured interviews with individuals and groups, and document review. Using thematic content and metaphor analysis to explore the case data, we found that each case was successful as an implementation project. However, the use of both passive and active adaptive management was constrained by deeply entrenched social norms and institutional frameworks. We identified seven “imperatives” that guided the behavior of project stakeholders, and that have consequences for the use of adaptive management. Reference to recent evaluations of the Adaptive Management Areas of the Pacific Northwest of the United States suggests that some of these imperatives and their consequences have broad applicability. The implications of our findings are discussed, and suggestions for improving the outcomes of regional scale adaptive management are provided.  相似文献
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