Search results for "Slop"
showing 10 items of 157 documents
Physically-based and distributed approach to analyze rainfall-triggered landslides at watershed scale
2011
Abstract Landslides are a serious threat to life and property throughout the world. The causes of landslides are various since multiple dynamic processes are involved in driving slope failures. One of these causes is prolonged rainfall, which affects slope stability in different ways. Water infiltrating in a hillslope may cause a rise of the piezometric surface, which, in turn, involves an increase of the pore water pressure and a decrease of the soil shear resistance. For this reason, knowledge of spatio-temporal dynamics of soil water content, infiltration processes and groundwater dynamics, is of considerable importance in the understanding and prediction of landslides dynamics. In this …
The influence of slope angle on sediment, water and seed losses on badland landscapes
1997
Abstract By means of simulated rainfall the influence of the slope angle on the soil, water and seed erosion has been studied on badland surfaces. Slope angle has a clear positive effect controlling soil erodibility and erosion rates, but it does not have any influence on the volume of runoff after 40 minutes of rain at an intensity of 55 mm h−1. In contrast, slope angle has a clear influence on runoff initiation, with cracks and crusts as the main factors controlling the time to ponding and time to runoff. Both ponding and runoff initiation start earlier on pediments than on slopes, where more cracks exist. Steady-state infiltration rates and seed losses have an inverse relationships with …
The influence of geomorphological position and vegetation cover on the erosional and hydrological processes on a Mediterranean hillslope
1998
Soil erosion and runoff rates are assumed to be highly dependent on slope position. However, little knowledge exists about the hydrogeomorphological processes at the pedon scale that support this idea. In order to assess the hydrological and erosional behaviour of soils at different slope positions, simulated rainfall experiments (55 mm was applied during one hour) were carried out on a south-facing slope with underlying limestone in south-east Spain. In the mean terms, the erosion rates (9 g m2 hr−1) and the runoff coefficients (12%) were very low at the scale of measurement (0·25 m2). The slope position does not affect erosion rates when the measurements are carried out under extreme dry …
Defining minimum runoff length allows for discriminating biocrusts and rainfall events
2021
This study was started in the context of the research projects PECOS (REN2003-04570/GLO) and PREVEA (CGL2007-63258/BOS) , both funded by the Spanish National Plan for RD&I and by the European ERDF Funds (European Regional Development Fund) , and continued during the project SCIN (Soil Crust In-terNational, PRI-PIMBDV-2011-0874, European project of ERA-NET BIODIVERSA, the Spanish team being funded by the Spanish Ministry of Economy and Competitiveness) . The work was finally supported and culminated by the DINCOS project (CGL2016-78075-P, Spanish State Programme for Scientific Research) and by the European ERDF Funds (Euro-pean Regional Development Fund) . Consuelo Rubio's partici-pation was…
Soil aggregate stability in three Mediterranean environments
1996
Abstract This paper considers the effect of vegetation on soil aggregate stability in three different Mediterranean landscapes in Southeast Spain. Soils on limestone, marls and clays, with two levels of vegetation cover at each north-facing slopes of the study areas, were investigated. Three aggregate stability tests (CND, TDI and UD) based on the drop impact and ultrasonic dispersion methods and the Emerson dispersion test were performed. The results of the experiments show the positive influence of vegetation on aggregate stability. However, vegetation is less important than lithology in influencing soil aggregate stability. Soil depth and moisture also affect aggregation, but the relatio…
Quick and Slow Components of the Hydrologic Response at the Hillslope Scale
2016
It is widely recognized that the Hortonian mechanism of runoff generation occurs in arid and semi-arid regions, generally characterized by high rainfall intensity on soils exhibiting low infiltrabilities. Differently, in steeply sloping forested watersheds in humid climates, by infiltrating through a highly permeable upper soil horizon, water moves beneath the soil surface determining a slow response. However, in most real cases, for example when in arid regions mountain forested areas take place, both (quick and slow) runoff generation processes coexist and together contribute to the hydrologic hillslope response. In this paper, based on analytical solutions of the hydrologic response, ins…
One-Dimensional Transient Analysis of Rainfall Infiltration in Unsaturated Volcanic Ash
2015
The paper presents a one-dimensional hydro-mechanical analysis of rainfall infiltration in a loose volcanic ash and the utilisation of a factor of safety for the implementation of an early-warning system. Three different rainy seasons with different rainfall patterns were analysed . The analysis aims to understand the influence of the antecedent rainfall on the wetting front, the pore-water pressures and the factor of safety. The analysis was carried out in the context of a Master project of the first author at the Laboratory for Soil Mechanics of EPFL.
Analysis of soil surface component patterns affecting runoff generation. An example of methods applied to Mediterranean hillslopes in Alicante (Spain)
2008
Spatial patterns of soil surface components (vegetation, rock fragments, crusts, bedrock outcrops, etc.) are a key factor determining hydrological functioning of hillslopes. A methodological approach to analyse the patterns of soil surface components at a detailed scale is proposed in this paper. The methods proposed are applied to two contrasting semi-arid Mediterranean hillslopes, and the influence of soil surface component patterns on the runoff response of the slopes was analysed. A soil surface components map was derived from a high resolution photo-mosaic obtained in the field by means of a digital camera. Rainfall simulation experimental data were used to characterise the hydrologica…
Simplified Probabilistic-Topologic Model for Reproducing Hillslope Rill Network Surface Runoff
2015
AbstractThis work presents a simplified probabilistic-topologic model for reproducing rill network surface runoff on a square-plane hillslope. The model requires only two parameters: the first is related to the production capacity of overland flow of the hillslope, at the initial conditions of the process, and the second depends on the sinuosity of the rill network. From a hydrological point of view, the following parameters account for the effects that essentially delineate the hydrologic response of a natural hillslope: rainfall intensity, hillslope roughness, and slope. Obviously, the reliability of the model is pending experimental validation that has only just begun. However, a prelimi…
Variable power-law scaling of hillslope Hortonian rainfall–runoff processes
2019
Hydrological studies focused on Hortonian rainfall–run-off scaling have found that the run-off depth generally declines with the plot length in power-law scaling. Both the power-law proportional coefficient and the scaling exponent show great variability for specific conditions, but why and how they vary remain unclear. In the present study, the scaling of hillslope Hortonian rainfall–run-off processes is investigated for different rainfall, soil infiltration, and hillslope surface characteristics using the physically based cell-based rainfall-infiltration-run-off model. The results show that both temporally intermittent and steady rainfalls can result in prominent power-law scaling at the …