Search results for "surface runoff"
showing 10 items of 241 documents
Influence of vegetation recovery on soil hydrology and erodibility following fire: an 11-year investigation
2005
The present study investigates long-term changes in soil hydrological properties and erodibility during the regrowth of different types and densities of vegetation following a severe wildfire in the Serra Grossa Range, eastern Spain. Twelve plots of similar slope and soil characteristics, naturally recolonized by four different plant species (trees, herbs, shrubs and dwarf shrubs) were examined using rainfall simulations during an 11-year period. The mean erosion rate was 80 g m−2 h−1, 6 months after the fire under wet-winter conditions, declining to 30 g m−2 h−1 in the following summer and reaching <10 g m−2 h−1 after 2 years. Considerable variation under the different vegetation types …
The effect of ash and needle cover on surface runoff and erosion in the immediate post-fire period
2008
Abstract Hillslopes are thought to be most susceptible to enhanced surface runoff and erosion immediately following wildfire due to removal of protective vegetation and litter cover, and in many cases a fire-induced reduction in soil wettability. This enhanced susceptibility declines as vegetation and litter layer recover. For logistical reasons, however, few studies have been able to examine the responses of burnt terrain immediately following burning and little is therefore known about the effect of the wettable ash layer that often covers the ground until it is redistributed or removed by wind or water erosion. Here we quantify the effects of ash and needle cast ground cover on surface r…
Flood events in Mediterranean ephemeral streams (ramblas) in Valencia region, Spain
2001
This article deals with flood events in Mediterranean ephemeral streams typical of the Valencia region. The combination of the basin physical characteristics steep slopes, sparse vegetation, thin soils and permeable rock. and intense, heavy and irregularly distributed rain, generates flash floods. Runoff generation is sudden, giving rise to flash floods with sharp, narrow hydrographs with short time lags. The high amount of runoff is, nevertheless, only a small fraction of the total rainfall, since the characteristics of the river basins are such that infiltration of large amounts of water occurs. Using daily hydrological data from the Rambla de la Viuda basin and 5-min data from both the B…
Empirical determination of the average annual runoff coefficient in the Mediterranean area
2014
Runoff estimation in ungauged basin is a challenge for the hydrological engineers and planners. For an y hydrological study on an ungauged basin, a methodology has to be appropriately selected for the determination of runoff at its outlet. Several meth ods have been used to estimate the basin runoff production. In this study the empirical Kennessey m ethod to determine average annual runoff coefficien t, RC, is tested on 61 Sicilian basins characterized b y different climate conditions, surface permeabilit y, mean slope and vegetation cover. A comparison between observed and calculated RC showed that a calibration of the Kennessey model could be necessary. The slight and not satisfying impr…
Shrubland as a soil and water conservation agent in Mediterranean-type ecosystems
2015
John Thornes found that shrubland was a key factor in the control of soil erosion on Mediterranean hillsides. His research inspired many scientists to investigate the impact of shrubland changes and management in semi-arid ecosystems. An example of Professor Thornes’ scientific influence is the experiment carried out on the El Teularet–Sierra de Enguera experimental station since 2003 which showed erosion rates on a 30-year-old abandoned orchard with dense vegetation cover of Ulex parviflorus and Cistus albidus and a 20-year-old fire-affected maquia with Quercus coccifera, Pistacia lentiscus and Juniperus oxycedrus. The measurements demonstrated that the shrubs help create more stable soil …
Changes in the seasonal snow cover of alpine regions and its effect on soil processes: A review
2007
Abstract At its maximum annual development, snow can cover more than half the Northern Hemisphere land area with one-third experiencing seasonal snow cover. The precise conditions that develop during the annual pattern of snowpack development formation have implications for: (i) soil microbiological activity and nutrient transformations; (ii) the capacity of the accumulating snowpack to retain atmospheric derived solutes; (iii) preferential elution and rapid runoff of solutes from the snowpack during periods of thaw; and (iv) leaching of solutes. Long-term records of annual snow accumulation suggest that substantial, regional scale shifts in snowpack characteristics have been occurring. The…
Exploiting the topographic information in a PDM-based conceptual hydrological model
2014
In this work, a conceptual lumped model was developed to simulate runoff and analyze hydrological processes with the goal of incorporating the morphological information into a probability-distributed model (PDM). PDMs usually describe the process of runoff generation as the result of soil saturation excess caused by precipitation with soil storage capacity represented by a spatially distributed quantity and described by a probability distribution. The proposed model, called topography-based probability distributed model (TOPDM), based on a simple water balance whose components are basin soil moisture storage, precipitation, drainage to groundwater, evapotranspiration, and Dunnian and Horton…
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…
Simuladores de lluvia y su aplicación a la Geomorfología : Estado de la cuestión
2013
During the last decades, Geomorphologists have developed a huge variety of scientific instruments as in the field as in the laboratory. Within the invented apparatus stand out the rainfall simulators, which have been used with different objectives since the 30s. His scientific benefit produced an increase in the variety of sizes, drop-formers, frames, rainfall characteristics, etc., for rainfall simulators based on drop former (tips) and on spray-nozzles systems. This paper reviews the history and the evolution of the rainfall simulators, and discusses the advantages and inconvenience of the simulated rainfall. We also point out the main uses: soil erosion rates measurements runoff, infiltr…