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A small laboratory flume on a 0.035 m m −1 slope was used to examine particle selection in shallow flows. Initial experiments were carried out on smooth surfaces to measure travel rates of different sediment sizes. Grain size fractions were introduced by hand into 1.37 × 10 −4 to 3.96 × 10 −4 m 2 s −1 flows, and clear selective mobility occurred with slowest...
The effect of forest fire on rainfall-runoff-erosion relationships at the micro-scale (plot) and at the meso-scale (hillslope) were studied in a Mediterranean mountainous region near Haifa, Israel. Rainfall simulation experiments were carried out on several plots at different times since the fire. Runoff and sediment yield were collected during the experiments. Soil samples from the upper soil layer...
This paper presents a relatively simple, two-dimensional hillslope erosion-deposition model: the model differs from most geomorphological models in that it does not assume that erosion by surface wash is always transport-limited. As a first test, the model is applied to an agricultural catchment in Central Belgium. Here, patterns of past erosion and deposition can be deduced from information contained...
This paper presents results on the temporal and spatial variability of the erosional system in two adjacent cultivated catchments located in the Belgian Loam belt. Annual catchment erosion rates, calculated for the whole catchment area, range between 1 and 15 m 3 /ha · y. Mean annual catchment erosion rates calculated for a three year period, were 5.4 m 3 /ha · y and 8.2 m 3 ...
Dilatometry can be used in geomorphology as an evaluation method for the behaviour of rocks during weathering by frost shattering and also for the role of unfrozen water migration during this process. It has already been demonstrated in other publications that calcareous rock cylinders undergoing humidification/drying cycles (no freezing) vary in length. These length changes are most significant when...
The recognition of alternating flood- (FDRs) and drought-dominated regimes (DDRs) in coastal rivers of New South Wales has helped to explain some of the changes in channels and floodplains observed in more recent times. Complex responses, as adjustments to regime shifts and to human-induced catchment and channel changes, can to some extent be forecasted using conceptual models. These in turn can be...
In field measurements of soil erosion spatial variability is usually neglected. Due to natural site conditions, however, considerable variations of runoff and soil loss can occur even within apparently homogeneous fields. This was observed on large (75 m 2 ) erosion test plots in triple replication in a forage-maize cropping experiment. The variability, with mean coefficients of variation...
The relationship between cover density and soil loss under simulated rainstorms of 30 and 60-minute duration and 33 mm h −1 intensity was investigated. Soil loss varied from 0–7.3 g m −2 for cover of 55–95% and reached maximum values of over 80.0 g m −2 (30-minute storms) and 140.0 g m −2 (60-minute storms) for cover of 25% or less. A critical threshold occurred at...
Loess soils are among the most erodible soils. Therefore, evaluating and enhancing infiltration is paramount in controlling soil loss. A laboratory study was conducted to evaluate the relative difference in infiltration among selected loess surface and subsurface soils from Belgium, Canada, China, and the United States, representing the major loess belts of the Northern Hemisphere. Soils were subjected...
According to Wolman and Miller (1960) the high geomorphic power of extreme events is compensated by its low frequency, because the product of a power function (cause-effect relationship) by a negative exponential (frequency distribution of the causes) tends to zero for high values. This result is adequate for extreme values, but the difference between the most frequent (modal) events and those which...
A landscape integrated survey was carried out on the badlands area in the Upper Orcia River Valley (Siena, Italy). A methodology has been investigated to explain the soil response to dynamic and anthropic factors from an erosion hazard point of view.The Upper Orcia River Valley is one of the many neogenic basins linked to the Pliocene sea ingression, in Tuscany and all over Italy. Sediments are mainly...
Studies on badland areas in the Vallcebre basin (Pyrenees) suggest that erosion rates are controlled by the weathering rate of mudrocks. To obtain the temporal pattern of physical weathering and its control on the erosive processes, monitoring of regolith temperatures at different aspect, depth and lithology, and periodical determination of regolith moisture and bulk density were carried out. Changes...
An anomalous multiple channel pattern in bedrock is observed on a predominantly downcutting reach of the Narmada River. The multi-channel reach (800-2750 m in width and 8500 m in length) is bounded by major faults, and is underlain by granite and gneiss bedrock. Geomorphological investigations reveal differences among the upstream, middle and downstream sub-reaches of the multi-channel study area...
Following the extreme rainfall event of 22 September 1992 in Southeastern France, an attempt was made to characterize the response of areas cultivated under vines to heavy precipitation. This response was determined in three ways by means of rainfall simulation experiments. First, the infiltration rate is calculated as the difference between rainfall and runoff rates. Secondly, the flow depths are...
The southern border of the Paris Basin has undergone successive weathering events during the Tertiary. Fluviatile and lacustrine deposits are scattered, being mainly confined to several North-South trending grabens. These are generally devoid of fossils which would allow them to be dated. A discontinuous blanket of weathering products is the main record of this long period of continental evolution...
Gravelly floodplain deposits and six terrace treads in the Waimea Plains, northeast Southland, New Zealand, range in age from ca. 1000 years old to 350,000 yr old. Deposits are progressively more weathered with increasing parent material age. Soils developed in them are classified as Recent Soils, Brown Soils and Ultic Soils in the New Zealand Soil Classification and Udifluvents, Dystrochrepts,...
A near-surface layer of vesicles may be found in many dryland soils, often below a stony desert pavement. During and after rain the uppermost part of the regolith develops a surface seal, trapping air which is compressed and which may also subsequently expand as a result of solar heating. This results in the deformation of the soft regolith and the formation of a vesicular layer just below the surface...
A chronosequence of soils on alluvial terraces in the Appalachian highlands of the southeastern United States is identified by simple methods of quantitative soil morphology and chemical analysis. The chronosequence is from Brasstown Creek, a 5th order stream draining 65 km 2 of the Blue Ridge Mountains of north Georgia. The portion of the valley studied is about 1 km wide and contains five...
A new high space/time resolution distributed sensitivity analysis is presented and used to examine the impact of simple variations in initial conditions on inundation predictions derived from a two dimensional finite element model of river channel/floodplain flow. Specifically changes in the specification of the floodplain topographic surface and the upstream boundary condition are considered for...
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