Search results for " Runoff"
showing 10 items of 262 documents
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…
Trends in nutrient concentrations in Latvian rivers and the response to the dramatic change in agriculture
2003
In recent years, the use of fertilisers in the Baltic countries (Estonia, Latvia, and Lithuania) has decreased at an unprecedented rate. The import of mineral fertilisers and feed stuff became almost non-existent, and extensive slaughtering of livestock reduced the amount of manure. In Latvia, the purchase of mineral fertilisers decreased by a factor of 15 between 1987 and 1996 and the number of livestock decreased with a factor of almost 4 during the same time period. Such abrupt and comprehensive changes in land use have never before occurred in the history of modern European agriculture. Here, the impact that this dramatic reduction has had on concentrations of nutrients in Latvian river…
The effect of patchy distribution ofStipa tenacissimaL. on runoff and erosion
1997
In south-east Spain, a semi-arid area,Stipa tenacissima(alphagrass) covers large natural and semi-natural areas with a mosaic of tussocks and bare zones. However, little knowledge exists about the influence of these patterns on runoff and erosion. In order to understand the hydrological and erosional behaviour of the vegetated (herbs andalphagrass) and bare zones, rainfall simulation experiments were carried out at three sites in south-east Spain. The experiments showed that surface runoff and erosion is negligible in the tussock and quite high in the bare areas. High infiltration rates and deep wetting fronts were measured in the vegetated patches, and lower infiltration rates and shallowe…
Human induced soil erosion and gully system development in the Late Holocene and future perspectives on landscape evolution: The Myjava Hill Land, Sl…
2013
In humid climate zones, like Central Europe, past soil erosion and gullying are strongly connected with agricultural expansion, and extreme soil erosion events often play an important role in land abandonment. This paper provides a case study to demonstrate the interaction between land use, soil erosion, floodplain development, and land use changes in a 0-order catchment in the Babikovce catchment, Myjava Hill Land, situated in western Slovakia. Sedimentological, pedological, geoarchaeological and historical data indicate two main periods of intensive hillslope erosion and gullying since the High Middle Ages. In particular, a few extreme precipitation events (or rapid snowmelts) caused inte…
Uncertainty analysis of the influence of rainfall time resolution in the modelling of urban drainage systems
2005
In urban drainage modelling, rainfall temporal variability can be considered as one of the most critical knowledge elements when dealing with rainfall–runoff models input data. The rainfall data temporal resolution usually available for practical applications is often lower than that requested for the rainfall–runoff simulation in urban areas, greatly compromising model accuracy. The present paper evaluates the influence of rainfall temporal resolution on the uncertainty of the response of rainfall–runoff modelling in urban environments. Analyses have been carried out using historical rainfall–discharge data collected for about 10 years in Parco d'Orleans experimental catchment (Palermo, It…
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…
Forecasted changes in the climate and the river runoff regime in Latvian river basins
2012
The hydrological model HBV (Hydrologiska Byråns Vattenbalansavdelning model) has been applied to six river basins in Latvia to assess climate change and its impacts on the river runoff regime at the end of the 21st century. Climate change has been predicted by applying the regional climate model RCAO with the driving boundary conditions from the global general circulation model HadAM3H applied for the IPCC scenarios A2 and B2 and the following time periods: 1961–1990 (control) and 2071–2100 (scenario). Changes have been found under both scenarios. Major changes in the future hydro-climate data were forecasted according to the A2 scenario, where the trends of increase are identified for the …
Monitoring and predicting sediment yield in a small Sicilian basin
2001
Identifying areas of a basin that are most sensitive to erosion have stimulated the study of within–basin variability of the sediment–delivery processes and the use of spatially distributed models. To verify the reliability of a sediment–delivery distributed model applicable at the morphological unit scale (i.e., the area of clearly defined aspect, length, and steepness), experiments were carried out at mean annual and event scales in a small Sicilian basin. A Geographical Information System is briefly presented into which the measurements carried out at the basin outlet (runoff, sediment yield, etc.) and other point and areal information (soil erodibility, digital terrain model, etc.) were…
The impact of road and railway embankments on runoff and soil erosion in eastern Spain
2015
Abstract. Road and railway infrastructure increased in the Mediterranean region during the last three decades. This included the building of embankments, which are assumed to be a~large source of sediments and runoff. However, little is known about soil erosion rates, the factors that control them, and the processes that contribute to detachment, transport and deposition of sediments from road and railway embankments. The objective of this study was therefore to assess the impacts of road and railway embankments as a source of sediment and water, and compare them to other land use types (citrus plantations and shrublands) representative of the Cànyoles watershed to evaluate the importance o…
The influence of aspect and vegetation on seasonal changes in erosion under rainfall simulation on a clay soil in Spain
1998
The seasonal and spatial variability of soil erosion under contrasting slope aspects in southeastern Spain was studied by performing and interpreting 84 rainfall simulation experiments conducted at an intensity of 55 mm h−1 during 1 h. The vegetated soils on the north-facing slope and the upper afforested parts had negligible sediment yield, runoff and erosion, while the bare soils on the south-facing slope had very high runoff rates. Runoff sediment concentration decreased over time during simulated rainfall events on the vegetated areas while it increased on the bare ones. Solute release decreased over time on both surface types. Seasonally, runoff sediment concentration was highest in a…