Preface     

Monique Pick  Gérard Trottett 《Solar physics》1987,111(1):vii-vii

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A modification to the Soil Conservation Service curve number method for steep slopes in the Loess Plateau of China   总被引：9，自引：0，他引：9  

Mingbin Huang  Jacques Gallichand  Zhanli Wang  Monique Goulet 《水文研究》2006,20(3):579-589

The Soil Conservation Service curve number (CN) method is widely used for predicting direct runoff from rainfall. However, despite the extent of cultivation on hillslope areas, very few attempts have been made to incorporate a slope factor into the CN method. The objectives of this study were (1) to evaluate existing approaches integrating slope in the CN method, and (2) to develop an equation incorporating a slope factor into the CN method for application in the steep slope areas of the Loess Plateau of China. The dataset consisted of 11 years of rainfall and runoff measurements from two experimental sites with slopes ranging from 14 to 140%. The results indicated that the standard CN method underestimated large runoff events and overestimated small events. For our experimental conditions, the optimized and non‐optimized forms of the slope‐modified CN method of the Erosion Productivity Impact Calculator model improved runoff prediction for steep slopes, but large runoff events were still underestimated and small ones overpredicted. Based on relationships between slope and the observed and theoretical CN values, an equation was developed that better predicted runoff depths with an R² of 0·822 and a linear regression slope of 0·807. This slope‐adjusted CN equation appears to be the most appropriate for runoff prediction in the steep areas of the Loess Plateau of China. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Rôle des héritages latéritiques et du niveau des nappes dans l'évolution des modelés et des sols en zone intertropicale forestière humide     

Dieudonné Bitom  Boris Volkoff  Anicet Beauvais  Frédérique Seyler  Paul-Désiré Ndjigui 《Comptes Rendus Geoscience》2004,336(13):1161-1170

Analysis of landscapes and soil covers from the outer to the inner part of a $75\text{km}\times 60\text{km}$ watershed in the South-Cameroon rainforest zone, characterized by important remnants of inherited ferricretes and stable hydrostatic base levels, indicates that the development of present landforms has not involved significant erosion by slope retreat because of the relative preservation of downslope residual ferricrete and that soil covers have vertically decayed under in situ geochemical process. To cite this article: D. Bitom et al., C. R. Geoscience 336 (2004).  相似文献   

Spatial versus temporal patterns in fish assemblages of a tropical estuarine coastal lake: The Ebrié Lagoon (Ivory Coast)     

Jean-Marc Ecoutin  Emilie Richard  Monique Simier  Jean-Jacques Albaret 《Estuarine, Coastal and Shelf Science》2005,64(4):623-635

The fish assemblages of the Ebrié lagoon (Ivory Coast) were sampled by experimental fishing over the entire lagoon using a purse seine net. The sampling was conducted in the two main hydroclimatic seasons for this ecosystem, i.e. in the dry season (March–April) and in the wet season (August–September). The results obtained showed a fish assemblage organized around a consistently occurring group of twenty species. When analysed in terms of ecological categories, the seasonal influence led to a cycle in the assemblages from freshwater to marine around this permanent species pool, with a seasonal renewal of the assemblage. At the scale of the lagoon, there were variations in the composition of the assemblages that clearly distinguished the western part from the eastern one. The limit was situated at the Vridi canal, a wide artificial channel permanently connecting the lagoon to the sea. To the west, the assemblage was characterised by a strong spatial uniformity and low seasonal variability. To the east, the assemblage formed two different entities; one assemblage with pronounced freshwater affinities occurring in a side arm and the other assemblage with great seasonal variability under the alternating influence of seawater in the dry season and freshwater in the wet season. This part of the lagoon functioned somewhat like a typical estuary.  相似文献   

Quantifying the local influence at a tall tower site in nocturnal conditions     

David?WerthEmail author  Robert?Buckley  Gengsheng?Zhang  Robert?Kurzeja  Monique?Leclerc  Henrique?Duarte  Matthew?Parker  Thomas?Watson 《Theoretical and Applied Climatology》2017,127(3-4):627-642

The influence of the local terrestrial environment on nocturnal atmospheric CO₂ measurements at a 329-m television transmitter tower (and a component of a CO₂ monitoring network) was estimated with a tracer release experiment and a subsequent simulation of the releases. This was done to characterize the vertical transport of emissions from the surface to the uppermost tower level and how it is affected by atmospheric stability. The tracer release experiment was conducted over two nights in May of 2009 near the Department of Energy’s Savannah River Site (SRS) in South Carolina. Tracer was released on two contrasting nights—slightly stable and moderately stable—from several upwind surface locations. Measurements at the 329-m level on both nights indicate that tracer was able to mix vertically within a relatively short (～24 km) distance, implying that nocturnal stable conditions do not necessarily prevent vertical dispersion in the boundary layer and that CO₂ measurements at the tower are at least partly influenced by nearby emissions. A simulation of the tracer release is used to calculate the tower footprint on the two nights to estimate the degree to which the local domain affects the tower readings. The effect of the nocturnal boundary layer on the area sampled by the tower can be seen clearly, as the footprints were affected by changes in stability. The contribution of local sources to the measurements at the tower was minimal, however, suggesting that nocturnal concentrations at upper levels are contributed mostly by regional sources.  相似文献   

Fractal properties of temperature fluctuations in the convective surface layer     

Szymon P. Malinowski  Monique Y. Leclerc 《Boundary-Layer Meteorology》1994,71(1-2):169-187

Temperature fluctuations in a convective surface layer were investigated. Box counting analysis was performed to investigate fractal properties of surfaces of constant temperature and was performed on sets of points obtained by setting thresholds on detrended records. Results indicate that surfaces of constant temperature have fractal properties for thresholds far from the mean. Estimated fractal dimensions of one-dimensional cuts through these surfaces varied between 0.23 and 0.66, increasing with threshold value approaching the mean temperature. For thresholds close to the mean, no fractal behavior was found. Asymmetry in results for thresholds above and below the mean temperature was attributed to the asymmetry between updrafts and downdrafts in the convective surface layer.The temperature dissipation rate (TD) was also investigated. It was found to be strongly intermittent with large fluctuations of the intermittency exponent. Moments were analyzed in order to investigate multifractal properties of TD. Results indicate scaling in the range of 50–1000 (where is the Kolmogorov scale) and multifractal properties resembling those observed for passive scalar dissipation in laboratory flows.  相似文献   

Coproducing urban space: Rethinking the formal/informal dichotomy          下载免费PDF全文

Martijn Koster  Monique Nuijten 《Singapore journal of tropical geography》2016,37(3):282-294

Providing an introduction to the special section ‘Close encounters: ethnographies of the coproduction of space by the urban poor’, this article sets out to argue that the image of ‘the informal’ as unruly, messy and dirty continues to inform urban planning around the world. As a reaction to this view, it contends that the informal and formal should be analysed as interconnected and that the informal sphere should be revalued. Urban development is studied as close encounters between established practices, with a locus and a history (tree‐like), and newly emerging, unstable and untraceable practices (rhizomatic). Contrary to the tendency in urban planning to conflate the formal with the tree and the informal with the rhizome, we argue that from the perspective of marginal urbanites, formal planning tends to be very arbitrary and frightening (rhizomatic), whereas informal practices can be very predictable and stable (arboreal). The article analyses residents of marginalized urban areas as inventive navigators who explore the changing physical, spatial and sociopolitical environment, avoiding threats and looking for opportunities, grounded in their everyday practices and life histories. The article concludes that marginal urbanites should be acknowledged as coproducers of urban space and that the right to ‘coproduce’ the city lies at the heart of the call for the right to the city.  相似文献   

Protracted river response to medieval earthquakes     

Amelie Stolle  Wolfgang Schwanghart  Christoff Andermann  Anne Bernhardt  Monique Fort  John D. Jansen  Hella Wittmann  Silke Merchel  Georg Rugel  Basanta Raj Adhikari  Oliver Korup 《地球表面变化过程与地形》2019,44(1):331-341

Mountain rivers respond to strong earthquakes by rapidly aggrading to accommodate excess sediment delivered by co-seismic landslides. Detailed sediment budgets indicate that rivers need several years to decades to recover from seismic disturbances, depending on how recovery is defined. We examine three principal proxies of river recovery after earthquake-induced sediment pulses around Pokhara, Nepal's second largest city. Freshly exhumed cohorts of floodplain trees in growth position indicate rapid and pulsed sedimentation that formed a fan covering 150 km² in a Lesser Himalayan basin with tens of metres of debris between the 11th and 15th centuries AD. Radiocarbon dates of buried trees are consistent with those of nearby valley deposits linked to major medieval earthquakes, such that we can estimate average rates of re-incision since. We combine high-resolution digital elevation data, geodetic field surveys, aerial photos, and dated tree trunks to reconstruct geomorphic marker surfaces. The volumes of sediment relative to these surfaces require average net sediment yields of up to 4200 t km^–2 yr^–1 for the 650 years since the last inferred earthquake-triggered sediment pulse. The lithological composition of channel bedload differs from that of local bedrock, confirming that rivers are still mostly evacuating medieval valley fills, locally incising at rates of up to 0.2 m yr^–1. Pronounced knickpoints and epigenetic gorges at tributary junctions further illustrate the protracted fluvial response; only the distal portions of the earthquake-derived sediment wedges have been cut to near their base. Our results challenge the notion that mountain rivers recover speedily from earthquakes within years to decades. The valley fills around Pokhara show that even highly erosive Himalayan rivers may need more than several centuries to adjust to catastrophic perturbations. Our results motivate some rethinking of post-seismic hazard appraisals and infrastructural planning in active mountain regions. © 2018 John Wiley & Sons, Ltd.  相似文献   

Adaptation of the SNOWMAP algorithm for snow mapping over eastern Canada using Landsat-TM imagery     

Karem Chokmani  Kristell Dever  Monique Bernier  Yves Gauthier  Lisa-Marie Paquet 《水文科学杂志》2013,58(4):649-660

Abstract

The snow mapping algorithm SNOWMAP was adapted to Landsat-TM data and to the context of eastern Canada. Six Landsat-5 TM scenes were used. It was found that the original version of SNOWMAP greatly underestimates snow cover extent. The modification made to the original algorithm, by cancelling the minimum threshold of 0.1 on the NDVI value, allows gaps to be filled in. In addition, a spatial correction procedure applied to the modified SNOWMAP algorithm results improves snow detection under coniferous forests. Based on a limited data set of ground-based observations (only 40 sites were available), the modified SNOWMAP seems to perform better in snow detection than the original version of the algorithm. An application case is presented in order to demonstrate the relevance of the modified SNOWMAP results as a high spatial-resolution reference for the validation of historical snow maps derived from medium spatial-resolution satellite data.

Citation Chokmani, K., Dever, K., Bernier, M., Gauthier, Y. & Paquet, L.-M. (2010) Adaptation of the SNOWMAP algorithm for snow mapping over eastern Canada using Landsat-TM imagery. Hydrol. Sci. J. 55(4), 649–660.  相似文献   

Amazonian floodplain water balance based on modelling and analyses of hydrologic and electrical conductivity data          下载免费PDF全文

Marie‐Paule Bonnet  Sébastien Pinel  Jérémie Garnier  Julie Bois  Géraldo Resende Boaventura  Patrick Seyler  David Motta Marques 《水文研究》2017,31(9):1702-1718

In the Amazon basin, floodplains form a complex mosaic of freshwater systems with differing morphologies, resulting in varied inundation patterns and heterogeneous chemical and ecological characteristics. In this study, we focused on the Janauacá floodplain, a medium‐sized system (786 km², including the local watershed) located along the Solimões River. Based on in situ and satellite observations acquired from November 2006 to November 2011, we computed water fluxes between the mainstream and the floodplain and examined the temporal dynamics of floodplain storage from river flooding, rainfall, runoff, and exchanges with groundwater through bank seepage for the 5 years from 2006 to 2011. The mainstream was the main input of water to the flooded area, accounting on average for 93% of total water inputs by the end of the water year. Direct precipitation and runoff from uplands contributed less than or equal to 5% and 10%, respectively. The seepage contribution was less than 1%. Model uncertainties, evaluated using Monte Carlo analysis of the input data and model parameters, showed that all water fluxes were relatively well constrained except for outflow through seepage, which had a standard deviation across simulations greater than 60%. The water balance computation was verified using electrical conductivity as an assumed non‐reactive tracer. Except during periods of very low water, the simulated and measured conductivities agreed well. Moreover, conductivity data analysis confirmed that the Janauacá system can be considered homogeneous in terms of electrical conductivity for filling percentages equal to or greater than 40% (i.e., when the water level is above 19.5 m, generally from April to August) but presented large heterogeneities during the rest of the hydrological cycle.  相似文献