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1.
The catchment of the river Adour (SW France) has been examined in order to analyse spatio-temporal variations in a number of key variables (flow, suspended matter, nitrate and dissolved orthophosphate concentrations) over a 25-year period (1972–1996).

Within the catchment area, it has been possible to discern how hydroclimatic fluctuations have affected the watershed, with dry periods in 1972–1976 and 1983–1993 alternating with wetter phases in 1977–1982 and 1994–1995. The anthropogenic activity, primarily, involving the use of water for agricultural purposes, has also had a major impact during this period, particularly in the downstream areas of the catchment.

Suspended matter fluxes display regular downstream increases with significant erosion being evident in the mountainous region contrasting with retention in the floodplains area downstream. These fluxes exhibit temporal and spatial variations with peaks occurring every 3–5 years, 1975–1977, 1979, 1982, 1985, 1987 and 1992. Some of these peaks are suggested to be related to anthropogenic activity involving river management, including the cutting of meanders and the construction of dykes for flood prevention.

Nitrate concentrations evince a similar pattern to the suspended matter fluxes with enhanced levels of downstream. The confluence of the Adour with the Midouze appears not to have any major impact on the nitrate concentration. In the downstream areas, an uptake of nitrate is registered indicating the activity of the riparian vegetation. For the entire catchment, maximal nitrate concentrations are observed in 1979, 1982, 1987, 1991–1992 and 1995.  相似文献   


2.
Among the most invasive species, the Coypu (Myocastor coypus) best exemplifies the widespread effect of alien species on ecosystems. Among the impacts, the induced erosion in riverbanks has an increasing economic and social importance. Despite its significance, this type of erosion is rarely quantified, and the available information is limited to local knowledge, grey literature, and maintenance reports. This research shows the potential of freely and instantly available Structure‐from‐Motion (SfM) photogrammetry to obtain crowdsourced information based on smartphone images. The results highlight how it is possible to provide a rough estimate of the damages with relatively low or null cost of application, and limited expert knowledge and expenditure of time, depending on the scale of analysis. The proposed technique provides a fresh approach to a known long‐standing issue, offering a new source of information for farmers, researchers, wildlife managers, as well as for land managers and planners. The potential applications of such a technique and its unprecedented ease of use and very low cost offer effective tools for management plans and scientific research, providing a basis to relate eroded volumes to the functioning of the drainage system and the connected agroecosystem. The method would also enable the opportunity of participatory and opportunistic crowdsourced sensing. Further scientific research on the crowd‐based data on erosion should encourage standardisation of data gathering and accessibility, together with a public involvement in information exchange, to generate a better understanding and awareness of erosion problems also for other fields of research. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

3.
Geobiology is a new discipline on the crossing interface between earth science and life science,and aims to understand the interaction and co-evolution between organisms and environments.On the basis of the latest international achievements,the new data presented in the Beijing geobiology forum sponsored by Chinese Academy of Sciences in 2013,and the papers in this special issue,here we present an overview of the progress and perspectives on three important frontiers,including geobiology of the critical periods in Earth history,geomicrobes and their responses and feedbacks to global environmental changes,and geobiology in extreme environments.Knowledge is greatly improved about the close relationship of some significant biotic events such as origin,radiation,extinction,and recovery of organisms with the deep Earth processes and the resultant environmental processes among oceans,land,and atmosphere in the critical periods,although the specific dynamics of the co-evolution between ancient life and paleoenvironments is still largely unknown.A variety of geomicrobial functional groups were found to respond sensitively to paleoenvironmental changes,which enable the establishment of proxies for paleoenvironmental reconstruction,and to play active roles on the Earth environmental changes via elemental biogeochemical cycles and mineral bio-transformations,but to be deciphered are the mechanisms of these functional groups that change paleoenvironmental conditions.Microbes of potential geobiology significance were found and isolated from some extreme environments with their biological properties partly understood,but little is known about their geobiological functions to change Earth environments.The biotic processes to alter or modify the environments are thus proposed to be the very issue geobiology aims to decipher in the future.Geobiology will greatly extend the temporal and spatial scope of biotic research on Earth and beyond.It has great potential of application in the domains of resource exploration and global change.To achieve these aims needs coordinative multidisciplinary studies concerning geomicrobiology and related themes,database and modeling of biogeochemical cycles,typical geological environments,and coupling of biological,physical,and chemical processes.  相似文献   

4.
Climate and land‐use changes could strongly affect wind erosion and in turn cause a series of environmental problems. Thus, the objective of this study was to assess potential wind erosion rate (PWER) response to climate and land‐use changes in the watershed of the Ningxia–Inner Mongolia Reach of the Yellow River (NIMRYR), China. The watershed of NIMRYR suffers from serious wind erosion hazards, and over recent decades, wind erosion intensity and distribution has changed, following climate and land‐use changes. To understand these processes in the NIMRYR watershed, the Integrated Wind Erosion Modelling System (IWEMS) and the Revised Wind Erosion Equation (RWEQ) were used to calculate the PWER under different climate conditions and land‐use scenarios, and to assess the influences of climate and land‐use changes on the PWER. The results show the PWER in the whole watershed had a significant declining trend from 1986 to 2013. The results of the relationship among PWER, climate change, and land‐use changes showed that climate change was the dominant control on the PWER change in this watershed. Compared to the period 1986–1995, the average PWER decreased 23.32% and 64.98% as a result of climate change in the periods 1996–2005 and 2006–2013, respectively. In contrast with climate change, the effects of land‐use changes on the average PWER were much lower, and represented a change in PWER of less than 3.3% across the whole watershed. The study method we used could provide some valuable reference for wind erosion modelling, and the research results should help climate and land‐use researchers to develop strategies to reduce wind erosion. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

5.
The profile characteristics and the temporal dynamics of soil moisture variation were studied at 26 locations in Da Nangou catchment (3.5 km2) in the loess area of China. Soil moisture measurements were performed biweekly at five depths in the soil profile (0–5, 10–15, 20–25, 40–45 and 70–75 cm) from May to October 1998 using Delta-T theta probe. Soil moisture profile type and temporal variation type and their relationship to topography and land use were identified by detrended canonical correspondence analysis (DCCA) and correlation analysis. The profile distribution of time-averaged soil moisture content can be classified into three types i.e. decreasing-type, waving-type and increasing-type. The profile features of soil moisture (e.g. profile gradient and profile variability) are influenced by different environmental factors. The profile type of soil moisture is only attributed to land use while profile gradient and profile variability of soil moisture is mainly related to land use and topography (e.g. landform type and slope). The temporal dynamics of layer-averaged soil moisture content is grouped into three types including three-peak type, synchro-four-peak type and lagged-four-peak type. These types are controlled by topography rather than by land use. The temporal dynamic type of soil moisture shows significant correlation with relative elevation, slope, aspect, while temporal variance displays significant relation with slope shape. The mean soil moisture is related to both the profile and dynamics features of soil moisture and is controlled by both land use and topography (e.g. aspect, position, slope and relative elevation). The spatial variability of soil moisture across landscape varies with both soil depths and temporal evolution.  相似文献   

6.
Increasing numbers of tourists are visiting the Antarctic. Totals from the past three seasons (1989–1990, 1990–1991, 1991–1992) were 2581, 4842, and 6495 respectively (Enzenbacher, 1992). Some environmental issues arising from Antarctic tourist activity include: wildlife tolerance, waste disposal, passenger education, tour operator management practices, personnel experience, frequency of visits and ship design. Current guidelines provide a practical approach to tourism, but do not address all issues arising from tourist activity. Antarctic Treaty Parties agreed to examine the question of a comprehensive regulation of tourist activities in the Antarctic Treaty Area and policies are under review. Some issues may prove difficult to resolve. Compliance with existing guidelines is to be encouraged, at least until more is known about the environmental effects of tourism. A management plan for tourism is needed along with more research on how tourism is conducted and the effects visits have on Antarctica's marine and terrestrial ecosystems. Cooperation between Treaty Parties and tour operators is important for the development of appropriate tourism regulations.  相似文献   

7.
Climate-induced drought has exerted obvious impacts on land systems in northern China. Although recent reports by the Intergovernmental Panel on Climate Change (IPCC) have suggested a high possibility of climate-induced drought in northern China, the potential impacts of such drying trends on land systems are still unclear. Land use models are powerful tools for assessing the impacts of future climate change. In this study, we first developed a land use scenario dynamic model (iLUSD) by integrating system dynamics and cellular automata. Then, we designed three drying trend scenarios (reversed drying trend, gradual drying trend, and acceleration of drying trend) for the next 25 years based on the IPCC emission scenarios and considering regional climatic predictions in northern China. Finally, the impacts of drying trend scenarios on the land system were simulated and compared. An accuracy assessment with historic data covering 2000 to 2005 indicated that the developed model is competent and reliable for understanding complex changes in the land use system. The results showed that water resources varied from 441.64 to 330.71 billion m3 among different drying trend scenarios, suggesting that future drying trends will have a significant influence on water resource and socioeconomic development. Under the pressures of climate change, water scarcity, and socioeconomic development, the ecotone (i.e., transition zone between cropping area and nomadic area) in northern China will become increasingly vulnerable and hotspots for land-use change. Urban land and grassland would have the most prominent response to the drying trends. Urban land will expand around major metropolitan areas and the conflict between urban and cultivated land will become more severe. The results also show that previous ecological control measures adopted by the government in these areas will play an important role in rehabilitating the environment. In order to achieve a sustainable development in northern China, issues need to be addressed such as how to arrange land use structure and patterns rationally, and how to adapt to the pressures of climate change and socioeconomic development together.  相似文献   

8.
In the twenty‐first century, fluvial geomorphologists are ideally placed to use their science in an applied manner, and provide guidance on environmental issues of concern. Understanding the impact of floods and droughts, land use and climate change, water use, etc. on river forms, processes and evolution requires that we understand interactions between water, sediment and vegetation, and how climate and anthropogenic impacts shape those interactions. More frequently, fluvial geomorphologists are asked to provide answers to a range of river issues, make forecasts about how systems might adjust in the future, and work with managers to implement strategies on‐the‐ground. To some, the field of fluvial geomorphology is underprepared for this task as several principles of landscape form, process and evolution are yet to be fully explored. Others however, see that geomorphologists have a suite of principles and tools at their disposal, and sufficient understanding to make forecasts about future river adjustments with some level of confidence. One concept that has been lost in recent years, but should lie at the heart of such analyses is that of river sensitivity. In this paper I draw on foundation literature to review the concept of river sensitivity. I provide examples that demonstrate how this concept could be reshaped and used for analyses at landform, reach and catchment scales. At the landform scale, morphological sensitivity is a function of textural and geometric sensitivity. At the reach scale, analyses consider inherent behavioural and change sensitivity. At the catchment scale river response and recovery are a function of locational, transmission and filter sensitivity. I then discuss how some temporal concepts can be used to consider how sensitivity in itself adjusts over time. Finally, I discuss future challenges for analysis of river sensitivity and consider how it could be used to improve geomorphological forecasting for use in river management. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

9.
The water quality along the River Kennet, in the Thames basin of southern England, was examined in terms of the influence of point- and diffuse-nutrient inputs. The river is supplied mainly from a Cretaceous Chalk aquifer and hence the waters are of a calcium bicarbonate type. The nitrate largely comes from agricultural sources, with concentrations decreasing downstream due to plant uptake and probable denitrification. In contrast, soluble reactive phosphorus (SRP) is largely associated with sewage inputs and concentrations increase downstream in line with effluents from major towns such as Newbury and Reading. Adjacent to the river in the lower half of the catchment is the Kennet and Avon Canal and the two are in places hydrologically connected. The canal inputs may influence calcium carbonate (calcite) precipitation and increase suspended sediment and particulate phosphorus concentrations in the river. Monitoring upstream and downstream of Marlborough sewage treatment works (STW) showed that SRP concentrations in the effluent were highly variable due to variable efficiency of P stripping and still sufficiently concentrated to dominate downstream river SRP with potential impacts on stream ecology. Biological recovery in this river following P stripping at STWs is complex and controlling those spikes in SRP that are above a threshold of 100 μg l−1 may be a critical requirement. More stringent effluent targets than are currently recommended may be needed (less than 800 μg RP l−1) to achieve good ecological status in this river depending on SRP concentrations upstream.  相似文献   

10.
Coastal marine ecosystems in many parts of the world are under unrelenting stress caused by urban development, hazardous or toxic substances, overfishing, habitat destruction, the introduction of exotic species and natural toxins. Biomonitoring plays a vital role in governmental and industrial strategies to identify, assess, control and reduce these problems. Sensitive and practical techniques in biomonitoring are needed in all of the strategic approaches – from toxic chemical rating and classification, to pollution source control, status and trends monitoring, and assessments of “marine ecosystem health”. Due to the shear magnitude and scope of the challenge, biomonitoring coastal ecosystems demands new and innovative approaches that are relatively easy and cheap to deploy and that provide timely and accessible information to environmental managers and policy makers.

This paper explores recent developments in microscale toxicity testing – a branch of aquatic toxicology involving the discovery and application of small-scale, innovative, sensitive, practical, inexpensive and frequently automated biological techniques. Highlights of a recent unique synthesis ([Reference to Wells et al., 1998]) are given, describing microscale tests at various biological and phylogenetic levels. Many of these tests are marine and focus on gametes, embryos and other young life stages. They can be utilized in the field (in vivo), with field collected samples, and in the laboratory. Their low cost, sensitivity, practicality and speed are their strengths, and commercial test kits have been developed as a result. But being largely “single-species” and sub-individual-level biomonitors, do such microscale tests provide information directly useful to protecting vital ecosystem processes? Indeed, how can this question be addressed? The needs and challenges of matching the most promising of the microscale tests with higher level (population, community, ecosystem) measurements to protect habitats and biodiversity are discussed. Improving marine biomonitoring and protecting coastal ecosystem health demands such new techniques within the context of new paradigms and rigorous approaches for their application.  相似文献   


11.
Laboratory culturing experiments with living Globigerina bulloides indicate that Mg/Ca is primarily a function of seawater temperature and suggest that Mg/Ca of fossil specimens is an effective paleotemperature proxy. Using culturing results and a core-top Neogloboquadrina pachyderma calibration, we have estimated glacial–interglacial changes in sea surface temperature (SST) using planktonic Mg/Ca records from core RC11-120 in the Subantarctic Indian Ocean (43°S, 80°E) and core E11-2 in the Subantarctic Pacific Ocean (56°S, 115°W). Our results suggest that glacial SST was about 4°C cooler in the Subantarctic Indian Ocean and 2.5°C cooler in the Subantarctic Pacific. Comparison of SST and planktonic δ18O records indicates that changes in SST lead changes in δ18O by on average 1–3 kyr. The glacial–interglacial temperature change indicated by the Subantarctic Mg/Ca records suggests that temperature accounts for 40–60% of the foraminiferal δ18O change. We have used the Mg/Ca-based SST estimates and δ18O determinations to generate site-specific seawater δ18O records, which suggest that seawater δ18O was on average 1‰ more positive during glacial episodes compared with interglacial episodes.  相似文献   

12.
The changing concepts and challenges that the process industry has to face in relation to environmental protection are discussed. The original requirements on industry to reduce emissions of contaminants through the installation of filters and waste water treatment facilities or through process modification and introduction of ‘clean production’ strategies were mainly based on economic and technical considerations rather than on an effort to avoid environmental impacts. The introduction of concepts such as ‘assimilative capacity of the environment’ and ‘critical load’ provided useful instruments for setting effect-related emission standards, resulting in acceptable environmental protection. However, the actual requirement for ‘sustainability’ has forced industry to focus not only on controlling emissions of contaminants and pollutants, but to take a global environmental approach, including the choice of raw materials and energy sources, recycling and re-utilization of wastes and to take responsibility for the fate of their products, during their whole lifecycle.  相似文献   

13.
Effects of agricultural land management practices on surface runoff are evident at local scales, but evidence for watershed‐scale impacts is limited. In this study, we used the Soil and Water Assessment Tool model to assess changes in downstream flood risks under different land uses for the large, intensely agricultural, Raccoon River watershed in Iowa. We first developed a baseline model for flood risk based on current land use and typical weather patterns and then simulated the effects of varying levels of increased perennials on the landscape under the same weather patterns. Results suggest that land use changes in the Raccoon River could reduce the likelihood of flood events, decreasing both the number of flood events and the frequency of severe floods. The duration of flood events were not substantially affected by land use change in our assessment. The greatest flood risk reduction was associated with converting all cropland to perennial vegetation, but we found that converting half of the land to perennial vegetation or extended rotations (and leaving the remaining area in cropland) could also have major effects on reducing downstream flooding potential. We discuss the potential costs of adopting the land use change in the watershed to illustrate the scale of subsidies required to induce large‐scale conversion to perennially based systems needed for flood risk reduction. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

14.
A summary is provided of the second in a series of Integrated Science Initiative workshops supported by the UNESCO International Hydrological Programme. The workshop brought together hydrologists, ecologists, biogeochemists, hydrogeologists and natural resource managers to discuss the processes that occur in hyporheic and riparian ecotones. The principal objectives were to share new ideas on the importance of biogeochemical processes that affect nutrients at the groundwater–surface water interface, to understand the impact of nutrient flux on stream (principally hyporheic) ecology, and to identify the management strategies for river corridors to mitigate the effects of nutrients applied to land and discharged via groundwater into rivers. The workshop concluded that: (1) more interdisciplinary research and environmental management practices are needed to better understand, predict and manage processes at the interface of environmental compartments; (2) the goal of environmental regulations to improve ecological health requires a holistic approach integrating our understanding of the ecological, hydrological, biogeochemical and physical processes; (3) upscaling spatially and temporally variable processes remains difficult and may hinder translation of research at micro‐scales (molecular to grain size) into macro‐scale (reach to catchment) decision‐making; (4) scientists need to better communicate existing research to river managers, while smanagers must better communicate policy and regulatory‐driven science requirements to researchers. Existing models, such as those that simulate stream–hyporheic exchange, are not widely known and rarely used by environmental managers. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

15.
Climate change will affect the regional ability to achieve the poverty reduction and sustainable development (SD) objectives. Thus, any action plans to achieve these objectives should make climate change policies an integral part of the development planning process. The best practices and measures of climate change policies should be implemented to ensure regional or community sustainability. In this paper, a case study that promotes the integration of carbon sequestration into sustainable forest management and rural development plan with multi-stakeholders participation is introduced. To achieve SD goals, appropriate tools and methods are required to address impacts of alternative forest land uses on carbon sequestration and rural sustainability, and to prioritise land use options. A range of forest land use scenarios that address various aspects of the forest carbon sequestration rate and rural sustainability are evaluated against a SD indicator system. Planting vegetation is one of the practical approaches in mitigating global warming by sequestrating carbon from the atmosphere to plant matter and soil. In order to protect environment, reduce excessive soil erosion, and decrease the propensity and frequency of flooding and other natural disasters, China has initiated nationwide pivotal projects such as “Grain for Green” to mitigate exacerbated environmental deterioration and degradation. Such ecological programs may affect the socio-economic livelihoods of peasants and the economic activities of the whole region. The impact and economic uncertainty associated with such projects urge policy makers to include all stakeholders in the decision making process so that an agreeable solution towards sustainable rural development can be identified. This study uses Liping County in Guizhou province as a case study to identify a consensus among peasants regarding planting selected tree-species. Analytic hierarchy process (AHP) is used as a multicriteria decision making tool to rank sustainability criteria and determine the priority of options. The method helps policy makers to understand what the peasants want to achieve by participating in a Grain for Green program and what their priorities are with respect to particular types of vegetation. The case study finds that economic and financial concerns are the most important drivers of the decision of which trees to plant among the peasants who took part in the implementation of the Grain for Green program. As a result of this, Gingko, redpine, and Chinese chestnut were the predominant trees planted under the program. The integrated assessment based on the AHP method provides an effective tool to help understand how economic, social and environmental factors are related to each other in affecting the nature of rural sustainability.  相似文献   

16.
Methodology for credibility assessment of historical global LUCC datasets   总被引：1，自引：0，他引：1  
Fang  Xiuqi  Zhao  Wanyi  Zhang  Chengpeng  Zhang  Diyang  Wei  Xueqiong  Qiu  Weili  Ye  Yu 《中国科学:地球科学(英文版)》2020,63(7):1013-1025
Land use-induced land cover change(LUCC) is an important anthropogenic driving force of global change that has influenced, and is still influencing, many aspects of regional and global environments. Accurate historical global land use/cover datasets are essential for a better understanding of the impacts of LUCC on global change. However, there are not only evident inconsistencies in current historical global land use/cover datasets, but inaccuracies in the data in these global dataset revealed by historical record-based reconstructed regional data throughout the world. A focus in historical LUCC and global change research relates to how the accuracy of historical global land cover datasets can be improved. A methodology for assessing the credibility of existing historical global land cover datasets that addresses temporal as well as spatial changes in the amount and distribution of land cover is therefore needed. Theoretically, the credibility of a global land cover dataset could be assessed by comparing similarities or differences in the data according to actual land cover data(the "true value"). However, it is extremely difficult to obtain historical evidence for assessing the credibility of historical global land cover datasets, which cannot be verified through field sampling like contemporary global land cover datasets. We proposed a methodological framework for assessing the credibility of global land cover datasets. Considering the types and characteristics of the available evidence used for assessments,we outlined four methodological approaches:(1) accuracy assessment based on regional quantitative reconstructed land cover data,(2) rationality assessment based on regional historical facts,(3) rationality assessment based on expertise, and(4) likelihood assessment based on the consistency of multiple datasets. These methods were illustrated through five case studies of credibility assessments of historical cropland cover data. This framework can also be applied in assessments of other land cover types, such as forest and grassland.  相似文献   

17.
Glacifluvial deposits along an ice-marginal zone in Småland, southern Sweden, have been dated using post-IR blue OSL. To test for incomplete bleaching, we adopted two strategies: analysis of modern analogues and small-aliquot dose distributions. Samples of modern fluvial sediments show no significant incomplete bleaching; they yield equivalent doses of only 0.5–2 Gy (0.25–4% of our glacifluvial sediment doses). Small-aliquot dose distributions do not provide any evidence for incomplete bleaching.

The sediments are believed to have been deposited during deglaciation and appear to fall into two age groups: 19–25 ka (mainly sandur sediments) and 33–73 ka (mainly deltaic sediments). Compared to the expected ages (13–15 ka), even the younger glacifluvial OSL ages appear up to 10 000 years (25 Gy) too old. The ages are nevertheless stratigraphically consistent and correspond between sites; we deduce that the 19–25 ka ages are true deposition ages. For glacifluvial sedimentation to take place on the South Swedish Upland at this time either a very early deglaciation is required, or alternatively ice-free conditions just prior to the LGM. The deltaic sediments (33–73 ka) were most likely not significantly bleached during deposition and thus they date events prior to the latest ice advance.  相似文献   


18.
Ballast water is a major pathway for the transfer of non-indigenous species in aquatic environments. The objectives of this study were to determine the ability of ozone to reduce the numbers of a spectrum of marine organisms collected from Puget Sound, Washington in replicated mesocosm (280 l) experiments, and estimate the minimum ozone concentrations as measured by total residual oxidant (TRO) required to reduce organism densities. Ozone treatment was effective in removing bacteria, phytoplankton, and mesozooplankton with initial TRO concentrations of 2–5 mg l−1 as Br2. Persistence of TRO resulted in an extended period of toxicity and cumulative mortality. TRO decay allowed bacteria populations to multiply when TRO levels fell below 0.5–1.0 mg l−1 as Br2. Phytoplankton chlorophyll a concentrations were rapidly reduced by ozone treatment and did not increase in any treatments or controls because of lack of light. Overall mesozooplankton viability was rapidly reduced by 90–99% in treatment TRO levels above 1.85 mg l−1 as Br2. Our study outlines novel protocols that can be used for testing different potential ballast water treatment systems in replicated and controlled mesocosm experiments.  相似文献   

19.
Under enhanced greenhouse conditions, climate models suggest an increase in rainfall intensities in the northern Hemisphere. Major flood events in the UK during autumn 2000 and central Europe in August 2002, have focussed attention on the dramatic impacts these changes may have on many sectors of society. In the companion paper [Fowler et al., J. Hydrol. (2004) this issue], we suggested that the HadRM3H model may be used with some confidence to estimate extreme rainfall distributions, showing good predictive skill in estimating statistical properties of extreme rainfall during the baseline period, 1961–1990. In this study, we use results from the future integration of HadRM3H (following the IPCC SRES scenario A2 for 2070–2100) to assess possible changes in extreme rainfall across the UK using two methods: regional frequency analysis and individual grid box analysis. Results indicate that for short duration events (1–2 days), event magnitude at a given return period will increase by 10% across the UK. For longer duration events (5–10 days), event magnitudes at given return periods show large increases in Scotland (up to +30%), with greater relative change at higher return periods (25–50 years). In the rest of the UK, there are small increases in the magnitude of more frequent events (up to +10%) but reductions at higher return periods (up to −20%). These results provide information to alter design storm depths to examine climate change impacts on various structures. The uncertainty bounds of the estimated changes and a ‘scaling’ methodology are additionally detailed. This allows the estimation of changes for the 2020s, 2050s and 2080s, and gives some confidence in the use of these estimates in impact studies.  相似文献   

20.
Tracing suspended sediment and particulate phosphorus sources in catchments   总被引：4，自引：0，他引：4  
Information on suspended sediment and particulate P (PP) sources is an important requirement in many catchment-based diffuse source pollution studies, in order to assist with model validation and to provide information to support the development of effective sediment and phosphorus control strategies. Such information is, however, frequently unavailable or difficult to assemble. In the study reported, source fingerprinting procedures were successfully used to assemble this information for seven sub-catchments in the Hampshire Avon catchment and five sub-catchments in the Middle Herefordshire Wye catchment. The results provide important new information on the relative importance of the contributions from surface and channel/subsurface sources to the suspended sediment and PP fluxes from the catchments. In the Wye sub-catchments channel/subsurface sources contributed 40–55% of the overall suspended sediment flux and 21–43% of the PP flux from the catchments. Equivalent values for the Avon were 1–41% and 1–54%, respectively. Combination of the information on the relative importance of surface and channel/subsurface sources with measured suspended sediment fluxes has provided the first estimates of the specific fluxes of sediment and PP attributable to channel/subsurface sources for UK catchments. The former are as high as 15–20 t km−2 year−1 in some of the Wye sub-catchments, whereas the latter exceeded 0.1 kgP ha−1 year−1 in the same sub-catchments. The results emphasize the need to take account of potential contributions from channel/subsurface sources when using measured suspended sediment and PP flux data to validate predictions derived from models incorporating only surface contributions.  相似文献   

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