Search results for "Runoff coefficient"
showing 10 items of 12 documents
Tillage Impacts on Initial Soil Erosion in Wheat and Sainfoin Fields under Simulated Extreme Rainfall Treatments
2021
The main aim of this research was to determine the potential effects of different tillage systems (TT: traditional tillage and RT: reduced tillage) on runoff and erosion at two different locations (Kahramanmaras and Tarsus, Southern Turkey) under (i) fallow, (ii) wheat (Triticumaestivum L.), and (iii) sainfoin (Onobrychissativa L.) crops. Rainfall simulations with intensity of 120 mm h&minus
Brevi considerazioni su piogge intense e potenzialità di produzione del deflusso superficiale in Sicilia
2013
Vengono presentati i metodi aggiornati per la stima delle precipitazioni intense massime annue di fissato tempo di ritorno in Sicilia. Dall‟osservazione della distribuzione spaziale dei parametri assunti nei modelli di stima emergono aree a maggior rischio riguardo l‟intensità di pioggia, qui commentate. Il richiamo a recenti studi che riguardano la produzione del deflusso superficiale a scala media annua o a scala di evento, consente di avanzare alcune considerazioni di tipo spaziale, con particolare attenzione all‟area del messinese, su questa importante propensione idrologica notoriamente fonte di dissesto idrogeologico e di pericolo alluvionale. The updated methods for the estimation of…
A rational runoff coefficient for a revisited rational formula
2019
The Rational Formula (RF) is probably the most frequently applied equation in practical hydrology to compute the peak discharge, due to its simplicity and effective compromise between theory and data availability. Thus, after more than a century, the estimation of peak discharge through the RF is still an important and challenging issue in hydrology. The RF assumes response linearity and sometimes assumes that the return period does not depend on the runoff coefficient and neglects the time to ponding and the antecedent moisture condition. Moreover, the RF requires the critical duration of rainfall and the runoff coefficient to be estimated, both of which are highly controversial. This pape…
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…
Influencia de la litología en los procesos de erosión en <i>badlands</i>. Los casos de Anna (Valencia) y Petrer (Alicante)
1997
By means of experiments with simulated rainfall the hydrological and erosional behaviour of degraded surfaces (badlands) developed on two different parent materials (marls and clays) is studied. On the Keuper clays, the ponding (4'07") and runoff (6' 36") initiation is delayed, the infiltration rates (38.63 mm h<sup>-1</sup>) are high, and the runoff coefficient (11.2 % after 30 minutes and 19.4 % after 60 minutes) and the erosion rates (13 g m<sup>2</sup> h<sup>-1</sup>) are low. On the contrary, over Cretaceous marls, the ponding (1’ 37") and the surface runoff (2' 52") initiation is very rapid, the infiltration rates are low (11.2 mm h<sup>-1<…
La formula razionale rivisitata
2019
The Rational Formula (RF), also known as CIA formula, is probably the most applied equation in practical hydrology to compute the peak discharge, due to its simplicity and effective compromise between theory and data availability. The RF assumes the linearity of the hillslope response, neglects the time to ponding and the antecedent soil moisture condition (ASMC), concentrates the infiltration effect in the runoff coefficient (C) which estimation is highly controversial, since it is based on qualitative indications. This paper proposes an advanced rational formula that makes it possible to derive the peak discharge at the hillslope scale, where the above assumptions are relaxed and which de…
A Comprehensive Check of Usle-Based Soil Loss Prediction Models at the Sparacia (South Italy) Site
2020
At first, in this paper a general definition of the event rainfall-runoff erosivity factor for the USLE-based models, REFe = (QR)b1(EI30)b2, in which QR is the event runoff coefficient, EI30 is the single-storm erosion index and b1 and b2 are coefficients, was introduced. The rainfall-runoff erosivity factors of the USLE (b1 = 0, b2 = 1), USLE-M (b1 = b2 = 1), USLE-MB (b1 ≠ 1, b2 = 1), USLE-MR (b1 = 1, b2 ≠ 1), USLE-MM (b1 = b2 ≠ 1) and USLE-M2 (b1 ≠ b2 ≠ 1) can be defined using REFe. Then, the different expressions of REFe were simultaneously tested against a dataset of normalized bare plot soil losses, AeN, collected at the Sparacia (south Italy) site. As expected, the poorest AeN predict…
Long-term erosional responses after fire in the Central Spanish Pyrenees
2005
Abstract This paper reports the results of a study on how fire effects water and sediment losses in the Central Spanish Pyrenees where land abandonment results in an increase of the scrubland and fire-affected surfaces. In 1991, two plots (control and burnt) were installed to collect runoff, suspended sediments and solutes. One of the plots was burnt (burnt-1) and the other was covered by shrubs and herbs (control). During 1993, another burnt plot was installed (burnt-2). Data was collected from the three plots until 1999 and is used as the basis for assessing the soil erosion changes after the fire. Runoff, solute and suspended sediment concentration and erosion rates were slightly greater…
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…
Modeling the probability distribution of peak discharge for infiltrating hillslopes
2017
Hillslope response plays a fundamental role in the prediction of peak discharge at the basin outlet. The peak discharge for the critical duration of rainfall and its probability distribution are needed for designing urban infrastructure facilities. This study derives the probability distribution, denoted as GABS model, by coupling three models: (1) the Green-Ampt model for computing infiltration, (2) the kinematic wave model for computing discharge hydrograph from the hillslope, and (3) the intensity-duration-frequency (IDF) model for computing design rainfall intensity. The Hortonian mechanism for runoff generation is employed for computing the surface runoff hydrograph. Since the antecede…