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.
A major challenge for geomorphologists is to scale up small‐magnitude processes to produce landscape form, yet existing approaches have been found to be severely limited. New ways to scale erosion and transfer of sediment are thus needed. This paper evaluates the concept of sediment connectivity as a framework for understanding processes involved in sediment transfer across multiple scales. We propose that the concept of sediment connectivity can be used to explain the connected transfer of sediment from a source to a sink in a catchment, and movement of sediment between different zones within a catchment: over hillslopes, between hillslopes and channels, and within channels. Using fluvial systems as an example we explore four scenarios of sediment connectivity which represent end‐members of behaviour from fully linked to fully unlinked hydrological and sediment connectivity. Sediment‐travel distance – when combined with an entrainment parameter reflecting the frequency–magnitude response of the system – maps onto these end‐members, providing a coherent conceptual model for the upscaling of erosion predictions. This conceptual model could be readily expanded to other process domains to provide a more comprehensive underpinning of landscape‐evolution models. Thus, further research on the controls and dynamics of travel distances under different modes of transport is fundamental. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

2.
Abstract

Rainfall–runoff induced soil erosion causes important environmental degradation by reducing soil fertility and impacting on water availability as a consequence of sediment deposition in surface reservoirs used for water supply, particularly in semi-arid areas. However, erosion models developed on experimental plots cannot be directly applied to estimate sediment yield at the catchment scale, since sediment redistribution is also controlled by the transport conditions along the landscape. In particular, representation of landscape connectivity relating to sediment transfer from upslope areas to the river network is required. In this study, the WASA-SED model is used to assess the spatial and temporal patterns of water and sediment connectivity for a semi-arid meso-scale catchment (933 km2) in Brazil. It is shown how spatial and temporal patterns of sediment connectivity within the catchment change as a function of landscape and event characteristics. This explains the nonlinear catchment response in terms of sediment yield at the outlet.

Citation Medeiros, P. H. A., Güntner, A., Francke, T., Mamede, G. L. & de Araújo, J. C. (2010) Modelling spatio-temporal patterns of sediment yield and connectivity in a semi-arid catchment with the WASA-SED model. Hydrol. Sci. J. 55(4), 636–648.  相似文献   

3.
The longitudinal functional connectivity of a river–lake–marsh system (RLMS) refers to the actual water-mediated transport of material from upstream to downstream areas along a spatial gradient and is fundamental to understand hydrological and biogeochemical cycles. However, due to a lack of consensus on appropriate data and methods, the quantification of connectivity is still a challenge, especially at the catchment scale. We developed a new method to evaluate longitudinal functional connectivity based on fluxes of materials (water, sediment, and chemicals) along a RLMS. The calculation of fluxes is based on the longitudinal pattern of terrain gradient, which influences transport efficiency, and on contributions from hillslopes, which set the initial spatial template of material loading to the RLMS. We evaluate the contributions from hillslopes to RLMS based on a new modified version of the index of sediment connectivity (IC) proposed by Borselli et al. (2008) and revised by Chartin et al. (2017).We applied this method to the Baiyangdian Basin covering an area of 3.4 × 104 km2 in China and quantified longitudinal functional connectivity during normal, wet, and dry periods(April, July and December) in year 2016. We found that areas with good structural connectivity exhibited poor functional connectivity during the normal and dry periods. Modelling testing with discharge data from hydrological stations and measured chemicals from Baiyangdian Lake was satisfactory in test periods. We conclude that public data and Digital Elevation Model-derived information can be used to reliably map the longitudinal functional connectivity of RLMSs. The proposed method provides a useful tool for monitoring and restoring the longitudinal functional connectivity of RLMSs and our results indicate that efforts aimed at restoring functional connectivity in RLMSs should take into account landscape patterns that can greatly influence fluxes in the watershed.  相似文献   

4.
Linking landscape morphological complexity and sediment connectivity   总被引：2，自引：0，他引：2  
Connectivity relates to the coupling of landforms (e.g. hillslopes and channels) and the transfer of water and sediment between them. The degree to which parts of a catchment are connected depends largely on the morphological complexity of the catchment's landscape. Landscapes can have very different and distinct morphologies, such as terraces, V‐shaped valleys or broad floodplains. The objective of this study is to better understand and quantify the relation between landscape complexity and catchment connectivity. We hypothesize that connectivity decreases with increasing landscape morphological complexity. To quantify the connectivity–complexity relationship virtual digital elevation models (DEMs) with distinct morphologies were used as inputs into the landscape evolution model LAPSUS to simulate the sediment connectivity of each landscape. Additionally, the hypothesis was tested on six common real DEMs with widely different morphologies. Finally, the effects of different rainfall time series on catchment response were explored. Simulation results confirm the hypothesis and quantify the non‐linear relation. Results from the exploration of sediment connectivity in response to sequences of rainfall events indicate that feedback between erosion and deposition are more important for certain landscape morphologies than for others: for a given rainfall input, a more effective sediment connectivity and erosion response may be expected from rolling or V‐shaped catchments than from dissected or stepped landscapes. Awareness of the differences in the behaviour and response of different morphologies to catchment processes provides valuable information for the effective management of landscapes and ecosystems through efficiently designed soil and water conservation measures. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

5.
Connectivity describes the efficiency of material transfer between geomorphic system components such as hillslopes and rivers or longitudinal segments within a river network. Representations of geomorphic systems as networks should recognize that the compartments, links, and nodes exhibit connectivity at differing scales. The historical underpinnings of connectivity in geomorphology involve management of geomorphic systems and observations linking surface processes to landform dynamics. Current work in geomorphic connectivity emphasizes hydrological, sediment, or landscape connectivity. Signatures of connectivity can be detected using diverse indicators that vary from contemporary processes to stratigraphic records or a spatial metric such as sediment yield that encompasses geomorphic processes operating over diverse time and space scales. One approach to measuring connectivity is to determine the fundamental temporal and spatial scales for the phenomenon of interest and to make measurements at a sufficiently large multiple of the fundamental scales to capture reliably a representative sample. Another approach seeks to characterize how connectivity varies with scale, by applying the same metric over a wide range of scales or using statistical measures that characterize the frequency distributions of connectivity across scales. Identifying and measuring connectivity is useful in basic and applied geomorphic research and we explore the implications of connectivity for river management. Common themes and ideas that merit further research include; increased understanding of the importance of capturing landscape heterogeneity and connectivity patterns; the potential to use graph and network theory metrics in analyzing connectivity; the need to understand which metrics best represent the physical system and its connectivity pathways, and to apply these metrics to the validation of numerical models; and the need to recognize the importance of low levels of connectivity in some situations. We emphasize the value in evaluating boundaries between components of geomorphic systems as transition zones and examining the fluxes across them to understand landscape functioning. © 2018 John Wiley & Sons, Ltd.  相似文献   

6.
Airborne gamma ray survey data were used to provide information on potassium, thorium and uranium concentrations in surface soil and rock in arid central Australia. Spatial patterns in these radioelements allow tracing of paths of sediment at catchment scale. Survey elevation data are combined with contour data to produce digital elevation models for terrain analysis, tracing of sediment flow paths and modelling of extreme floods. Gamma ray data show consistent variation with slope, a limited range of drainage areas, and erosion/deposition models derived from the conservation of mass equation. Supply‐limited sediment transport models give a reasonable reproduction of observed radioelement distribution but some elements of the distribution pattern reflect the area inundated by 500–1000 year floods rather than the effects of simple downslope movement. Partial area sediment supply models are derived by downstream accumulation of erosion and deposition rates calculated using the conservation of mass equation with transport laws based on slope alone and stream power. Comparison with observed radioelement patterns suggests that both transport laws apply in different parts of the landscape. Regional‐scale sediment transport models will require a range of models depending on location in the landscape and event frequency. This approach may allow estimation of sediment delivery ratios. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

7.
The degree of hydrological connectivity is mainly determined by the spatial organisation of heterogeneity. A meaningful and aggregate abstraction of spatial patterns is one of the promising means to gain fundamental insights into this complex interaction and can, moreover, be used as a tool to acquire a profound understanding of the major controls of catchment hydrology. In order to disclose such controls, pattern‐process relationships and the explanatory power of landscape metrics were tested by simulating the runoff of differently patterned virtual basins, generated by neutral landscape models and fractal networks and solved by a surface hydrological model composed of kinematic wave routing and Green‐Ampt infiltration. A total of 23 landscape metrics quantified the spatial patterns and were subsequently related to the functional connectivity, assessed as the proportion of internal runoff generation constituting the hydrological response at the outlet. Landscape metrics allowed the identification of dominant features of heterogeneity that explained the observed connectivity, and to disclose changes in control with class abundance. Therefore, landscape metrics are a useful tool for basin comparison and classification in terms of the dominant processes and the corresponding model structure requirements. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

8.
Hydrological connectivity inside the soil is related to the spatial patterns inside the soil (i.e., the structural connectivity). This, in turn, is directly associated with the physical and the chemical processes at a molecular level (i.e., the functional connectivity). Nuclear magnetic resonance (NMR) relaxometry can be successfully applied to reveal both structural and functional components of soil hydrological connectivity. In the present study, the low field NMR relaxometry was applied on water suspended soils sampled at the upstream‐ and downstream‐end of three different length plots. Also the sediments collected from the storage tanks at the end of each plot were water suspended and monitored by NMR relaxometry. The results from the NMR investigations were elaborated by using a mathematical approach in order to quantify both the functional and structural connectivity components. In particular, following integration of the T1 distribution curve, an S‐shaped curve was obtained. It revealed two plateaus corresponding to the shortest (low component) and the longest (high component) intervals of relaxation times, respectively. According to relaxometry theory, the two T1 intervals, associated to the different plateaus, were attributed to micro and macro soil pores, respectively. The two T1 intervals were used to define a functional connectivity index, while the central part of the S‐shaped distribution was used to define a structural connectivity index. Here we provide the physical meaning of the our mathematical approach, thereby revealing that functional connectivity index increases with plot length, as a result of a selective eroded particle transport. Moreover, the relationship structural connectivity index versus plot length resulted quasi‐independent of grainsize distribution, whereas the values of the structural connectivity index for the sediment samples resulted lower than those obtained for the corresponding soils.  相似文献   

9.
Catchment‐scale analyzes of spatial and temporal variability in landscape connectivity are critical considerations in appraisals of landscape evolution and disaster mitigation in tectonically active mountain belts such as Taiwan. This study uses historical aerial photographs, flow discharge and seismic data to analyze landslide changes and channel adjustments over a 30 year period in the Liwu Basin. Recurrent earthquakes and typhoon events trigger frequent landslide activity, channel adjustment and sediment reworking in this system. Spatial variability in magnitude–frequency relations of hillslope‐valley floor (lateral) and upstream–downstream (longitudinal) connectivity during the study period are shown to reflect annual reworking in source and accumulation zones, while partly‐confined valleys in the mid‐catchment area trap sediment behind landslide‐induced dams that are formed and breached on an approximately decadal basis. This promotes partial longitudinal connectivity in these areas. Landscape responses to disturbance events were especially pronounced following combinations of seismic and typhoon events prior to the 1998 and 2005 images. Although single high magnitude events and series of moderate events affect patterns of landscape connectivity in the Liwu Basin, residence times for sediment storage are very short in this highly‐connected river system, where confined valley settings extend virtually to the coast. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

10.
The effect of changes in catchment processes and conditions can be studied by using connectivity as a framework for understanding the feedbacks and interactions occurring within the system. The sediment record preserved in reservoirs can be a useful archive of catchment changes, but needs to be considered in conjunction with the different elements that compose and act on the system to take into account its complexity. Changing patterns of connectivity have been studied in the Ingbirchworth Catchment (Yorkshire, UK), using a multiple methodology approach combining the analysis of reservoir‐sediment records with knowledge of recent land‐use history, high resolution rainfall records, catchment characteristics and management aspects. Sedimentation rates inferred from reservoir‐sediment cores from two reservoirs in the Ingbirchworth catchment show sedimentation peaks which coincide with periods of significant changes in the catchment, such as the introduction of arable crops, the establishment of land drainage and the widespread intensification and mechanization of agriculture. Rainfall patterns, including combinations of events such as droughts and increased precipitation, contribute to increased sediment transfer under catchment conditions in which more sediment and/or new pathways are made available due to catchment changes. Sediment fingerprinting supports the notion that changes in sedimentation rates are not just related to increased/reduced erosion and transport in the same areas, but also to the establishment of different pathways increasing sediment connectivity. The results demonstrate that typical calculations of catchment‐area yields are not sufficient as sediment‐contributing areas vary as a consequence of changing conditions. The study provides insights into the complex interactions influencing connectivity, such as the relation between catchment changes and climatic inputs, and the subsequent effect on catchment conditions and transfer networks. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

11.
The sediment connectivity concept is particularly suitable for tackling complex, multidisciplinary questions through systems thinking. However, it is unclear how to directly measure connectivity, and so proxy variables are often applied by indices to provide estimates. In this study, we critically evaluate a broad range of connectivity indices encompassing structural and functional connectivity as well as hillslope channel coupling. We then discuss their role in providing a more holistic estimation of connectivity within the Tahoma Creek Watershed, WA. Of the 14 km of channel below the glacier front, the upper 6 km (0–6 km) are coupled to the adjacent hillslopes. Coupled reaches correspond to regions with a high proportion of area contributing sediment and relatively high connectivity values, where all measures decrease in the downstream direction. A significant transition occurs near river kilometer 6. Here the valley bottom abruptly widens, deposition occurs, and the hillslopes become decoupled from the active channel. This transitional reach is also identified as a geomorphic hotspot based on the network structure. The lower 8 km of channel downstream of this reach are largely depositional and percent contributing area and connectivity values remain low, eventually reaching a minimum. Despite their limitations, we found each method to provide unique and useful information regarding connectivity. The effect of scale and event magnitude on connectivity is illustrated. We also found vegetation, topographic characteristics, and network structure to be important in high-gradient glacio-volcanic landscapes. The choice of an index will depend on the research objectives, data availability, and the proxy variables that best describe the variability within the defined area.  相似文献   

12.
High-resolution topographic models have revolutionized monitoring of river changes by comparing sequential river topographic surveys (i.e. change detection). Nevertheless, much more may be obtained from this innovative quantification of changes. In this paper, we enhance the interpretation of geomorphic processes by presenting a new method for understanding of sources and sinks of sediment, river sediment transfers and functional sediment connectivity. Repeat digital elevation models (DEMs) obtained by photogrammetry were used to quantify topographic change after two floods by creating a DEM of difference (DoD) of a 6.5 km-long reach of Rambla de la Viuda stream, an ephemeral gravel-bed river in eastern Spain. The proposed method involved dividing the channel into 10 m-long longitudinal strips that were used to systematically draw boundaries between the erosional and depositional areas of the DoD. The analysis objectively: (i) drew a series of erosional and depositional segments, from 120 to 1360 m in length; (ii) estimated ranges of source-to-storage sediment transport distances, 320–670 m in the upstream and middle reaches and up to 2030 m in the lower reach; and (iii) obtained values of functional connectivity (i.e. the ratio between the sediment exported (erosion) and retained (deposition), ranging from 103 to 10−3). The variability in these three parameters along the river was found to be related to the level of channel disturbance by in-stream mining during the 1990s and 2000s. Additionally, this method indicates that the main process responsible for self-adjustment of the present morphosedimentary conditions is intra-reach erosion of banks and channel beds. Thus, this study proposes a new methodology to characterize morphological change, sediment transfer and connectivity that may serve as environmental indicators of the hydromorphological integrity of rivers with potential application to the European Water Framework Directive. © 2019 John Wiley & Sons, Ltd.  相似文献   

13.
Vegetation cover pattern is one of the factors controlling hydrological processes. Spatially distributed models are the primary tools previously applied to document the effect of vegetation cover patterns on runoff and soil erosion. Models provide precise estimations of runoff and sediment yields for a given vegetation cover pattern. However, difficulties in parameterization and the problematic explanation of the causes of runoff and sedimentation rates variation weaken prediction capability of these models. Landscape pattern analysis employing pattern indices based on runoff and soil erosion mechanism provides new tools for finding a solution. In this study, the vegetation cover pattern was linked with runoff and soil erosion by two previously developed pattern indices, which were modified in this study, the Directional Leakiness Index (DLI) and Flowlength. Although they use different formats, both indices involve connectivity of sources areas (interpatch bare areas). The indices were revised by bringing in the functional heterogeneity of the plant cover types and the landscape position. Using both artificial and field verified vegetation cover maps, observed runoff and sediment production on experiment plots, we tested the indices’ efficiency and compared the indices with their antecedents. The results illustrate that the modified indices are more effective in indicating runoff at the plot/hillslope scale than their antecedents. However, sediment export levels are not provided by the modified indices. This can be attributed to multi-factor interaction on the hydrological process, the feedback mechanism between the hydrological function of cover patterns and threshold phenomena in hydrological processes.  相似文献   

14.
Variability of interrill erosion at low slopes   总被引：2，自引：0，他引：2  
Numerous models and risk assessments have been developed in order to estimate soil erosion from agricultural land, with some including estimates of nutrient and contaminant transfer. Many of these models have a slope term as a control over particle transfer, with increased transfer associated with increased slopes. This is based on data collected over a wide range of slopes and using relatively small soil flumes and physical principals, i.e. the role of gravity in splash transport and flow. This study uses laboratory rainfall simulation on a large soil flume to investigate interrill soil erosion of a silt loam under a rainfall intensity of 47 mm h?1 on 3%, 6% and 9% slopes, which are representative of agricultural land in much of northwest Europe. The results show: (1) wide variation in runoff and sediment concentration data from replicate experiments, which indicates the complexities in interrill soil erosion processes; and (2) that at low slopes processes related to surface area connectivity, soil saturation, flow patterns and water depth may dominant over those related to gravity. Consequently, this questions the use of risk assessments and soil erosion models with a dominant slope term when assessing soil erosion from agricultural land at low slopes. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

15.
Models are widely used to simulate hydrological response and the generation and transport of constituents such as salt, phosphorus, and nitrogen from catchments to streams. Several models use a spatial representation with catchments divided into subcatchments. Variations in land use and other characteristics within subcatchments are represented by spatially lumped hydrologic response units (HRUs) or functional units instead of using fully distributed models. This approach disregards any spatial interaction between HRUs, including their connectivity to each other and to the stream and the influence of these interactions on water and constituent export. A spatially explicit hydrological model (Thales) was used to simulate a variety of theoretical catchments with soils dominated by combinations of infiltration excess, saturation excess, and subsurface stormflow processes and different soil constituent concentrations that were spatially interacting (i.e. located along a hillslope sequence). The modelling results show that the response of both runoff and concentration is sensitive to varying spatial arrangements due to interactions of runoff, infiltration, and chemical processes between the different soil types in many but not all situations. Results highlight the importance of considering connectivity of pathways when modelling hydrological response and constituents export. This is achieved by comparing pairs of simulations and the corresponding differences in the exported loads. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

16.
Recent emphasis on sediment connectivity in the literature highlights the need for quantitative baseline studies on the patterns and distribution of sediment stores to facilitate understanding of how sediment moves through the landscape at various temporal and spatial scales. This study evaluates the distribution and make‐up of sediment stores within the dramatically incised landscapes of the upper Yellow River, where basin fill deposits up to 1200 m in depth have been extensively reworked following incision by the Yellow River. Field and GIS analyses highlight the discontinuous distribution of sediment stores in Garang catchment, a 236 km2 tributary of the upper Yellow River. Volumetric estimates of sediment storage were obtained through a combination of field mapping, GPR transects, and GIS analyses. Sediment stores cover 20% of the Garang catchment, with an estimated volume of 474.0 × 106 m3, and inferred residence times from OSL and 14C dating of 103–104 years. Fans and terraces reworked from basin fill deposits, and associated cut and fill terrace features, are the dominant forms of sediment storage (~90% of total). A space‐for‐time argument is used to assess stages of basin infilling and subsequent landscape responses to incision, outlining a dramatic example of changes to sediment dynamics and connectivity relationships within the upper Yellow River. Sediments within the upper catchment lie above the regional basin fill level, offering a glimpse of pre‐incisional conditions. This contrasts markedly with the enduring influence of basin incisional history seen within the middle catchment, and the contemporary landscapes of the lower catchment where nearly all available sediment has been excavated from the basin and the landscape effectively operates under post‐incisional conditions. The need to contextualise catchment‐scale studies in terms of landscape history is emphasised. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

17.
High‐resolution digital elevation models (DEMs) from repeat LiDAR (light detection and ranging) or SfM (structure from motion) surveys have become an important tool in process geomorphology. The spatial pattern of negative and positive changes of surface elevation on raster DEMs of difference (DoD) can be interpreted in terms of geomorphic processes, and has been used for morphological budgeting. We show how the application of flow routing algorithms and flow accumulation opens new opportunities for the analysis of DoD. By accumulating the values of the DoD along downslope flowpaths delineated on a DEM, these algorithms lend themselves to computing the net balance, i.e. sediment yield (SY), for the contributing area of each cell. Doing the same for the negative subset of the DoD yields a minimum estimate of erosion (E) within the contributing area. The division of SY by E yields (a maximum estimate of) the sediment delivery ratio (SDR), that is the proportion of material eroded within the contributing area of each cell that has been exported from that area. The resulting SDR is a spatially distributed measure of functional sediment connectivity. In this letter, we develop the computationally simple approach by means of an example DoD from a lateral moraine section in the Upper Kaunertal Valley, Austrian Central Alps. We also discuss advantages, assumptions and limitations, and outline potential applications to connectivity research using field‐, laboratory‐, and model‐based DoD. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

18.
Intensive agricultural practices on sensitive soils induce high erosion rates in central Belgium. Expert-rules models quantify runoff and erosion at catchment scale, avoiding over-parameterization, and can include some direct or indirect connectivity features. The aim of this article is to test the ability of an expert-based model, LandSoil, to quantify runoff and to locate erosion and sedimentation areas in a small cultivated loamy catchment in Belgium during the years 2014, 2015 and 2016. Spatialized data are important for assessing model outputs and the erosive response. Measurements of runoff and observation of spatial erosion/deposition patterns, especially around major connectivity points, permitted an assessment of the reliability of the model results. Runoff modelling gave contrasting results (good linear adjustment at the outlet of the 83 ha sub-catchment (point 1): r2 of 0.96, Nash–Sutcliffe criterion of 0.95; less good at the outlet of the 3.9 ha sub-catchment (point 2): r2 of 0.28, Nash–Sutcliffe criterion of –0.47). For point 2 the poor results are explained by the very few runoff events observed, a scaling effect and the small area with a single land use. Graduated rulers demonstrate that the model is able to provide a coherent pattern of erosion/deposition. The study highlights great sensitivity to the effect of land use, land allocation, landscape design and slope gradients. Grass strips induce deposition of eroded particles when slopes are gentle (< 2%). Woodland strips decrease connectivity by being in the stream but deposit thinner sediment layers. Field boundaries have a role in the transport, but not really the quantity, of sediments. This model validation in the Belgian loess context allows us to use LandSoil in other similar environments in order to estimate the effects of landscape management scenarios. © 2020 John Wiley & Sons, Ltd.  相似文献   

19.
Roads in rural, upland landscapes are important sources of runoff and sediment to waterways. The downstream effects of these sources should be related to the connectivity of roads to receiving waters. Recent studies have explored this idea, but only simple metrics have been used to characterize connectivity and few studies have quantified the downstream effects of road–stream connectivity on sediment or solute budgets and channel morphology. In this study, we evaluated traditional and newly developed connectivity metrics that utilized features of landscape position and delivery pathway to characterize road–stream connectivity in upland settings. Using data on stream geomorphic conditions developed by the Vermont Agency of Natural Resources (Montpelier, VT), we related road connectivity metrics to channel condition on a set of 101 forested, upland streams with minimal development other than predominantly gravel road networks. Logistic regression indicated that measures of road density, proximity and orientation successfully distinguished among categories of stream geomorphic condition at multiple geographic scales. Discriminant function analysis using a set of inherent channel characteristics combined with road connectivity metrics derived at the reach corridor scale successfully distinguished channel condition for over 70% of the channels evaluated. This research contributes to efforts to evaluate the cumulative downstream effects of roads on stream channels and aquatic resources and provides a new means of watershed assessment to derive metrics that can be used to predict channel condition. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

20.
Connectivity has emerged in recent years as a significant conceptual framework within which to address the spatial and temporal variability in runoff and sediment transport. This special issue draws together several of the papers that were presented in the session “Connectivity in water and sediment dynamics: how do we move forwards?” at the 2012 General Assembly of the European Geosciences Union in Vienna, Austria. The papers submitted for this special issue fall into three groups: empirical studies, modelling studies, and conceptual development. Although it may be evident that the concept of connectivity helps us to express the complexity (in terms of water and sediment yields) of landscape responses to rainfall inputs, does it improve our ability to understand or predict those responses? There would still seem to be some way to go in connectivity research before this nagging concern can be assuaged. That it can be will undoubtedly be an important task for a number of ongoing research initiatives. Copyright © 2015 John Wiley & Sons, Ltd.  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