Search results for "erosion"
showing 10 items of 637 documents
COMPARISON OF TWO SIMPLIFICATION METHODS FOR SHORELINE EXTRACTION FROM DIGITAL ORTHOPHOTO IMAGES
2018
Abstract. The coastal ecosystems are very sensitive to external influences. Coastal resources such as sand dunes, coral reefs and mangroves has vital importance to prevent coastal erosion. Human based effects also threats the coastal areas. Therefore, the change of coastal areas should be monitored. Up-to-date, accurate shoreline information is indispensable for coastal managers and decision makers. Remote sensing and image processing techniques give a big opportunity to obtain reliable shoreline information. In the presented study, NIR bands of seven 1:5000 scaled digital orthophoto images of Riga Bay-Latvia have been used. The Object-oriented Simple Linear Clustering method has been utili…
Uncertainties in shoreline position analysis: the role of run-up and tide in a gentle slope beach
2017
Abstract. In recent decades in the Mediterranean Sea, high anthropic pressure from increasing economic and touristic development has affected several coastal areas. Today the erosion phenomena threaten human activities and existing structures, and interdisciplinary studies are needed to better understand actual coastal dynamics. Beach evolution analysis can be conducted using GIS methodologies, such as the well-known Digital Shoreline Analysis System (DSAS), in which error assessment based on shoreline positioning plays a significant role. In this study, a new approach is proposed to estimate the positioning errors due to tide and wave run-up influence. To improve the assessment of the wave…
An Approach for the Validation of a Coastal Erosion Vulnerability Index: An Application in Sicily
2022
In recent decades, coastal erosion phenomena have increased due to climate change. The increased frequency and intensity of extreme events and the poor sediment supply by anthropized river basins (dams, river weirs, culverts, etc.) have a crucial role in coastal erosion. Therefore, an integrated analysis of coastal erosion is crucial to produce detailed and accurate coastal erosion vulnerability information to support mitigation strategies. This research aimed to assess the erosion vulnerability of the Sicilian coast, also including a validation procedure of the obtained scenario. The coastal vulnerability was computed by means of the CeVI (Coastal Erosion Vulnerability Index) approach, whi…
Predicting soil loss on moderate slopes using an empirical model for sediment concentration
2011
Summary The objective of this investigation was to estimate event soil loss per unit area from bare plots in central and southern Italy using an empirical model for sediment concentration. The analysis was developed using data collected on bare plots differing in length (11–44 m) and slope (10–26%) at three Italian stations (Masse, Umbria; Caratozzolo, Calabria; Sparacia, Sicily). At first, an analysis was carried out, using the experimental data collected at Sparacia, to establish a relationship between sediment concentration and hydrological variables, such as runoff, rainfall amount and single storm erosion index. Then, an empirical model to estimate plot soil loss as a function of rainf…
Modelling sediment delivery processes by a stream tube approach
1999
Abstract The sediment delivery processes due to the travel along a hydraulic path having an uniform slope and to the concave shape of the path are modelled. In particular, using a power equation for modelling the slope profile and RUSLE with two different expressions of the topographic factors, a criterion to define the erosion active slope length, i.e. the slope length in which no deposition processes occur, is initially proposed. Then, the RUSLE equation is adapted to concave profiles by a correction factor of the topographic factors depending on slope curvature. Finally, the deduced relationships (equations (19) and (27)) for correcting the topographic factors for a concave slope are exp…
A new expression of the slope length factor to apply USLE-MM at Sparacia experimental area (Southern Italy)
2013
Abstract Predicting soil loss due to water erosion by empirical models is useful to assess the severity of the phenomenon in an area of interest and to predict the effect of alternative soil erosion control practices. The USLE scheme cannot be used at the Sparacia experimental area (Sicily, South Italy) to predict event soil loss per unit plot area, Ae, because experimental data suggest that, generally, Ae does not increase with plot length, λ. The USLE-MM scheme uses the runoff coefficient, QR, as an additional independent variable in order to develop an empirical model allowing prediction of storm soil loss values that do not necessarily increase with λ. According to this model, Ae is exp…
The “Soil Genetic Erosion”: a new threat for soils?
2015
During the 1990’s the concept of pedodiversity started to be diffused in the scientific literature and the decrement of the soil diversity in space and time - particularly due to human activity - has been seen as a sort of underhand problem affecting soil ecosystems, considering that different soil types face gradual or drastic reduction or complete loss of their unique “genetic features”. Pedodiversity has received considerable recent interest, especially as peculiar aspect of biodiversity and has been assessed by several authors by applying diversity indices used in ecology. This paper takes into consideration the influence of human activities on the loss of pedodiversity in a Mediterrane…
Testing assumptions and procedures to empirically predict bare plot soil loss in a Mediterranean environment
2014
Empirical prediction of soil erosion has both scientific and practical importance. This investigation tested USLE and USLE-based procedures to predict bare plot soil loss at the Sparacia area, in Sicily. Event soil loss per unit area, Ae, did not vary appreciably with plot length, λ, because the decrease in runoff with λ was offset by an increase in sediment concentration. Slope steepness, s, had a positive effective on Ae, and this result was associated with a runoff coefficient that did not vary appreciably with s and a sediment concentration generally increasing with s. Plot steepness did not have a statistically detectable effect on the calculations of the soil erodibility factor of bot…
Water erosion assessment and modeling in two calanchi areas in Sicily, Italy
I badlands sono forme di erosione localizzate principalmente nelle regioni aride e semi-aride e sono formati da una complessa combinazione di processi morfogenetici. La loro origine coinvolge processi di erosione idrica ma anche tunnel erosion e movimenti di massa. Inoltre, tali forme possono anche essere correlate a fenomeni di erosione accelerata che hanno luogo laddove le azioni antropiche disturbano l'equilibrio naturale tra processi morfogenetici e suolo. I badlands, con i loro versanti ripidi, sono spesso inseriti all’interno di paesaggi più dolci, in mezzo a colture o bosco, localizzati in aree dove i processi responsabili del loro modellamento sono di solito piuttosto attivi determi…