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The variability of hillslope form and function is examined experimentally using a simple model catchment in which most landscape development parameters are either known or controlled. It is demonstrated that there is considerable variability in sediment output from similar catchments, subjected to the same hydrological processes, and for which the initial hillslope profiles are the same. The results demonstrate that, in the case of catchments with a linear initial hillslope profile, the sediment output is initially high but reduces through time, whereas for a concave initial profile the sediment output was smaller and relatively constant. Concave hillslope profiles also displayed reduced sediment output when compared with linear slopes with the same overall slope. Using this experimental model catchment data, the SIBERIA landscape evolution model was tested for its ability to predict temporal sediment transport. When calibrated for the rainfall and erodible material, SIBERIA is able to simulate mean temporal sediment output for the experimental catchment over a range of hillslope profiles and rainfall intensities. SIBERIA is also able to match the hillslope profile of the experimental catchments. The results of the study provide confidence in the ability of SIBERIA to predict temporal sediment output. The experimental and modelling data also demonstrate that, even with all geomorphic and hydrological variables being known and/or controlled, there is still a need for long‐term stream gauging to obtain reliable assessments of field catchment hydrology and sediment transport. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Landscape evolution models provide a way to determine erosion rates and landscape stability over times scales from tens to thousands of years. The SIBERIA and CAESAR landscape evolution models both have the capability to simulate catchment–wide erosion and deposition over these time scales. They are both cellular, operate over a digital elevation model of the landscape, and represent fluvial and slope processes. However, they were initially developed to solve research questions at different time and space scales and subsequently the perspective, detail and process representation vary considerably between the models. Notably, CAESAR simulates individual events with a greater emphasis on fluvial processes whereas SIBERIA averages erosion rates across annual time scales. This paper describes how both models are applied to Tin Camp Creek, Northern Territory, Australia, where soil erosion rates have been closely monitored over the last 10 years. Results simulating 10 000 years of erosion are similar, yet also pick up subtle differences that indicate the relative strengths and weaknesses of the two models. The results from both the SIBERIA and CAESAR models compare well with independent field data determined for the site over different time scales. Representative hillslope cross‐sections are very similar between the models. Geomorphologically there was little difference between the modelled catchments after 1000 years but significant differences were revealed at longer simulation times. Importantly, both models show that they are sensitive to input parameters and that hydrology and erosion parameter derivation has long‐term implications for sediment transport prediction. Therefore selection of input parameters is critical. This study also provides a good example of how different models may be better suited to different applications or research questions. Copyright © 2010 John Wiley & Sons, Ltd and Commonwealth of Australia 相似文献
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Abstract A flow-interval hillslope discretization scheme is proposed for catchment hydrological modelling. By this scheme, a two-dimensional catchment is simplified into a one-dimensional cascade of flow intervals linked by the main stream. Each flow interval comprises a set of parallel hillslopes. The hillslope is the fundamental computational unit in the hydrological model providing lateral inflow to the main stream. The size of hillslope is determined by the catchment area and width functions. Catchment runoff is the total of hillslope responses through the river routing. Tests in four Japanese catchments showed that the model performed well on simulating the overall water balance, general flow pattern, and daily and hourly hydrographs of a whole catchment, as well as simultaneous simulation in different subcatchments. Characteristics of catchment hydrological responses and model applicability are discussed. 相似文献
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Chih‐Ming Tseng Ching‐Weei Lin Giancarlo Dalla Fontana Paolo Tarolli 《地球表面变化过程与地形》2015,40(8):1129-1136
In August 2009, the typhoon Morakot, characterized by a cumulative rainfall up to 2884 mm in about three days, triggered thousands of landslides in Taiwan. The availability of LiDAR surveys before (2005) and after (2010) this event offers a unique opportunity to investigate the topographic signatures of a major typhoon. The analysis considers the comparison of slope–area relationships derived by LiDAR digital terrain models (DTMs). This approach has been successfully used to distinguish hillslope from channelized processes, as a basis to develop landscape evolution models and theories, and understand the linkages between landscape morphology and tectonics, climate, and geology. We considered six catchments affected by a different degree of erosion: three affected by shallow and deep‐seated landslides, and three not affected by erosion. For each of these catchments, 2 m DTMs were derived from LiDAR data. The scaling regimes of local slope versus drainage area suggested that for the catchments affected by landslides: (i) the hillslope‐to‐valley transitions morphology, for a given value of drainage area, is shifted towards higher value of slopes, thus indicating a likely migration of the channelized processes and erosion toward the catchment boundary (the catchment head becomes steeper because of erosion); (ii) the topographic gradient along valley profiles tends to decrease progressively (the valley profile becomes gentler because of sediment deposition after the typhoon). The catchments without any landslides present a statistically indistinguishable slope–area scaling regime. These results are interesting since for the first time, using multi‐temporal high‐resolution topography derived by LiDAR, we demonstrated that a single climate event is able to cause significant major geomorphic changes on the landscape, detectable using slope–area scaling analysis. This provides new insights about landscape evolution under major climate forcing. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Attempts to reduce the number of parameters in distributed rainfall–runoff models have not yet resulted in a model that is accurate for both natural and anthropogenic hillslopes. We take on the challenge by proposing a distributed model for overland flow and channel flow based on a combination of a linear response time distribution and the hillslope geomorphologic instantaneous unit hydrograph (GIUH), which can be calculated with only a digital elevation model and a map with field boundaries and channel network as input. The spatial domain is subdivided into representative elementary hillslopes (REHs) for each of which we define geometric and flow velocity parameters and compute the GIUH. The catchment GIUH is given by the sum of all REH responses. While most distributed models only perform well on natural hillslopes, the advantage of our approach is that it can also be applied to modified hillslopes with for example a rectangular drainage network and terrace cultivation. Tests show that the REH‐GIUH approach performs better than classical routing functions (exponential and gamma). Simulations of four virtual hillslopes suggest that peak flow at the catchment outlet is directly related to drainage density. By combining the distributed flow routing model with a lumped‐parameter infiltration model, we were also able to demonstrate that terrace cultivation delays the response time and reduces peak flow in comparison to the same hillslope, but with a natural stream network. The REH‐GIUH approach is a first step in the process of coupling distributed hydrological models to erosion and water quality models at the REH (associated with agricultural management) and at the catchment scale (associated with the evaluation of the environmental impact of human activities). It furthermore provides a basis for the development of models for large catchments and urban or peri‐urban catchments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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This paper investigates the specific contributions of river network geomorphology, hillslope flow dynamics and channel routing to the scaling behavior of the hydrologic response as function of drainage area. Scaling relationships emerged from the observations of geomorphological and hydrological data and were reproduced in previous works through mathematical models, for both idealized self-similar networks and natural basins. Recent literature highlighted that scale invariance of hydrological quantities depends not only on the metrics of the drainage catchment but also on effective flow routing. In this study we employ a geomorphological width function scheme to test the simple scaling hypothesis adopting more realistic dynamic conditions than in previous approaches, specifically taking into account the role of hillslopes. The analysis is based on the derivation of the characteristic distributions of path lengths and travel times, inferred from DEM processing and measurements of rainfall and runoff data. The study area is located in the Tiber River region (central Italy).Results indicate that, while scaling properties clearly emerge when the hydrologic response is defined on the basis of the sole geomorphology, scale invariance is broken when less idealized flow dynamics are taken into account. Lack of scaling appears in particular as a consequence of the catchment to catchment variability of hillslope velocities. 相似文献
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Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time‐step, grid‐based, conceptual rainfall–runoff model was developed for the previously uninstrumented Neales River in the arid zone of northern South Australia. Hourly, logged stage data provided a record of stream‐flow events in the river system. In conjunction with opportunistic gaugings of stream‐flow events, these data were used in the calibration of the model. The poorly constrained spatial variability of rainfall distribution and catchment characteristics (e.g. storage depths) limited the accuracy of the model in replicating the absolute magnitudes and volumes of stream‐flow events. In particular, small but ecologically important flow events were poorly modelled. Model performance was improved by the application of catchment‐wide processes replicating quick runoff from high intensity rainfall and improving the area inundated versus discharge relationship in the channel sections of the model. Representing areas of high and low soil moisture storage depths in the hillslope areas of the catchment also improved the model performance. The need for some explicit representation of the spatial variability of catchment characteristics (e.g. channel/floodplain, low storage hillslope and high storage hillslope) to effectively model the range of stream‐flow events makes the development of relatively complex rainfall–runoff models necessary for multisite ecological studies in large, ungauged arid zone catchments. Grid‐based conceptual models provide a good balance between providing the capacity to easily define land types with differing rainfall–runoff responses, flexibility in defining data output points and a parsimonious water‐balance–routing model. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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A quantitative, process relevant analysis of ten mesoscale (ca 10–90 km2) catchments in the Cairngorm mountains, Scotland was carried out using 10‐m digital terrain models (DTMs). This analysis produced a range of topographic indices that described differences in the landscape organisation of the catchments in a way that helped explain contrasts in their hydrology. Mean transit time (MTT)—derived from isotopic tracer data—was used as a metric that characterised differences in the hydrological function of the ten catchments. Some topographic indices exhibited significant correlations with MTT. Most notably, the ratio of the median flow path length to the median flow path gradient was negatively correlated with MTT, whilst the median upslope area was positively correlated. However, the relationships exhibited significant scatter which precluded their use as a predictive tool that could be applied to ungauged basins in this region. In contrast, maps of soil hydrological properties could be used to differentiate hydrologically responsive soils (which are dominated by overland flow and shallow sub‐surface storm flow) from free draining soils (that facilitate deeper sub‐surface flows). MTT was negatively correlated with the coverage of responsive soils in catchments. This relationship provided a much better basis for predicting MTT in ungauged catchments in this geomorphic province. In the Cairngorms, the extensive cover of various glacial drift deposits appears to be a first order control on soil distributions and strongly influences the porosity and permeability of the sub‐surface. These catchment characteristics result in soil cover being a much more discerning indicator of hydrological function than topography alone. The study highlights the potential of quantitative landscape analysis in catchment comparison and the need for caution in extrapolating relationships between landscape controls and metrics of hydrological function beyond specific geomorphic provinces. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Field measurement and modelling of soil erosion provides insights into landscape systems as well as the potential for enhanced landscape management. There are a number of field and numerical methods by which soil erosion and deposition can be quantified. Here we examine the capability of the SIBERIA landscape evolution model to quantify short-term erosion and deposition on a well-managed cattle grazing landscape on the east coast of Australia. The model is calibrated by two methods (1) a geomorphological approach using a site digital elevation model (DEM) and soil data and (2) a laboratory-scale flume. The two calibration processes resulted in similar model input parameters and estimated erosion rates of 3.1 t ha−1 year−1 and 4.4 t ha−1 year−1, respectively. These were found to closely match erosion rates estimated using the environmental tracer 137Cs (2.7–4.8 t ha−1 year−1). However, erosion and deposition estimated at individual points along the hillslope was not well correlated with 137Cs at the same position due to the temporal averaging of the model and microtopography. Sensitivity analysis showed the model was more sensitive to parameterisation than sub-DEM-scale topography. This places confidence in the model's ability to estimate erosion and deposition across an entire hillslope and catchment on decadal time scales. We also highlight the robustness and flexibility of the calibration methods. 相似文献
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Nature can provide analogues for post‐mining landscapes in terms of landscape stability and also in terms of the rehabilitated structure ‘blending in’ with the surrounding undisturbed landscape. In soil‐mantled landscapes, hillslopes typically have a characteristic pro?le that has a convex upper hillslope pro?le with a concave pro?le lower down the slope. In this paper hillslope characteristic form is derived using the area–slope relationship from pre‐mining topography at two sites in Western Australia. Using this relationship, concave hillslope pro?les are constructed and compared to linear hillslopes in terms of sediment loss using the SIBERIA erosion model. It is found that concave hillslopes can reduce sediment loss by up to ?ve times that of linear slopes. Concave slopes can therefore provide an alternative method for the construction of post‐mining landscapes. An understanding of landscape geomorphological properties and the use of erosion models can greatly assist in the design of post‐mining landscapes. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Sediment in urban stormwater systems creates a significant maintenance burden, while a lack of coarse-grained bed sediment in streams limits their ecological value and geomorphic resilience. Gravel substrates, for example, provide benthic habitat yet are often scoured from the channel bed only to end up in a detention basin or treatment wetland. This dual problem of both ‘too much’ and ‘too little’ coarse-grained sediment reflects a watershed sediment budget that is profoundly altered. We developed a conceptual urban coarse-grained (>0.5 mm) sediment budget across three domains: hillslopes (urban land surfaces), the built stormwater network and stream channels. We then quantified key sources, sinks and storages for a suburban case study, using a combination of hillslope and in-channel monitoring, and interrogation of local government records. Around 36% of the sediment supplied to the stormwater network reached the catchment outlet, a level of sediment delivery much higher than observed in similar-sized natural catchments. The remainder was deposited in the sediment cascade and either stored, or extracted and removed from the catchment (e.g. material deposited in sediment ponds and gross pollutant traps). Conventional urban drainage networks are characterized by high hillslope sediment supply and low storage, resulting in efficient sediment delivery. Channel erosion, deposition in (and extraction from) pipes and channels, and floodplain deposition are small compared to sediment transport through the cascade. An understanding of the sediment budget of urban headwater catchments can provide stormwater and waterway managers with the information they need to address specific sediment problems such as sedimentation in stormwater assets and geomorphic recovery of urban streams. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd. 相似文献
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Gullying is a significant process in the long‐term dynamics and evolution of both natural and rehabilitated (i.e. post‐mining) landscapes. From a landscape management perspective it is important that we understand gully initiation and development, as it is well recognized that catchment disturbance can result in the development of gullies that can be very difficult to rehabilitate. This study examines gully position using geomorphic statistics relating to features such as depth, width and length in a catchment undisturbed by European activity in the Northern Territory, Australia. The results demonstrate that gullying occurs throughout the catchment and that a slope–area threshold does not exist and that gully position broadly follows the catchment area–slope relationship. Simple relationships relating catchment area and slope to gully depth, width and length provide poor results, despite these relationships having been found to apply for ephemeral gullies in cropland. The results suggest that gully initiation thresholds are low as a result of an enhanced fire regime. A threshold model for gully position that uses catchment area and slope to switch between gully and hillslope was evaluated and found broadly to capture gully position. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Distributed erosion models, which simulate the physical processes of water flow and soil erosion, are effective for predicting soil erosion in forested catchments. Although subsurface flow through multiple pathways is dominant for runoff generation in forested headwater catchments, the process-based erosion model, Geo-spatial interface for Water Erosion Prediction Project(Geo WEPP), does not have an adequate subsurface component for the simulation of hillslope water flow. In the current study, t... 相似文献
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We report erosion rates and processes, determined from in situ‐produced beryllium‐10 (10Be) and aluminum‐26 (26Al), across a soil‐mantled landscape of Arnhem Land, northern Australia. Soil production rates peak under a soil thickness of about 35 cm and we observe no soil thicknesses between exposed bedrock and this thickness. These results thus quantify a well‐defined ‘humped’ soil‐production function, in contrast to functions reported for other landscapes. We compare this function to a previously reported exponential decline of soil production rates with increasing soil thickness across the passive margin exposed in the Bega Valley, south‐eastern Australia, and found remarkable similarities in rates. The critical difference in this work was that the Arnhem Land landscapes were either bedrock or mantled with soils greater than about 35 cm deep, with peak soil production rates of about 20 m/Ma under 35–40 cm of soil, thus supporting previous theory and modeling results for a humped soil production function. We also show how coupling point‐specific with catchment‐averaged erosion rate measurements lead to a better understanding of landscape denudation. Specifically, we report a nested sampling scheme where we quantify average erosion rates from the first‐order, upland catchments to the main, sixth‐order channel of Tin Camp Creek. The low (～5 m/Ma) rates from the main channel sediments reflect contributions from the slowly eroding stony highlands, while the channels draining our study area reflect local soil production rates (～10 m/Ma off the rocky ridge; ～20 m/Ma from the soil mantled regions). Quantifying such rates and processes help determine spatial variations of soil thickness as well as helping to predict the sustainability of the Earth's soil resource under different erosional regimes. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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This paper investigates the effect of introducing spatially varying rainfall fields to a hydrological model simulating runoff and erosion. Pairs of model simulations were run using either spatially uniform (i.e. spatially averaged) or spatially varying rainfall fields on a 500‐m grid. The hydrological model used was a simplified version of Thales which enabled runoff generation processes to be isolated from hillslope averaging processes. Both saturation excess and infiltration excess generation mechanisms were considered, as simplifications of actual hillslope processes. A 5‐year average recurrence interval synthetic rainfall event typical of temperate climates (Melbourne, Australia) was used. The erosion model was based on the WEPP interrill equation, modified to allow nonlinear terms relating the erosion rate to rainfall or runoff‐squared. The model results were extracted at different scales to investigate whether the effects of spatially varying rainfall were scale dependent. A series of statistical metrics were developed to assess the variability due to introducing the spatially varying rainfall field. At the catchment (approximately 150 km2) scale, it was found that particularly for saturation excess runoff, model predictions of runoff were insensitive to the spatial resolution of the rainfall data. Generally, erosion processes at smaller sub‐catchment scales, particularly when the sediment generation equation had non linearity, were more sensitive to spatial rainfall variability. Introducing runon infiltration reduced the total runoff and sediment yield at all scales, and this process was also most sensitive to the rainfall resolution. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献