0000000000530579
AUTHOR
Maria Angela Serio
Raindrop size distribution and terminal velocity for rainfall erosivity studies. A review
Abstract The knowledge of the rainfall drop size distribution (DSD) at the land surface is essential for understanding precipitation mechanisms affecting soil erosion processes. Rainfall erosivity is defined as the potential of rain to cause erosion and it can be evaluated by rainfall kinetic power, which is determined by DSD and raindrop terminal velocity. This paper firstly deals with the raindrop terminal velocity estimate. Then the most widely used DSD are reviewed highlighting the difference between the raindrop size distribution per unit volume of air and that per unit area and time. The reliability of the available kinetic power-rainfall intensity relationships and their application …
Deducing the stage-discharge relationship of rectangular broad and sharp-crested contraction devices
Flumes with a local contraction of the channel width are a common way for accurately measuring the flow discharge. In this paper, the outflow process of rectangular broad and sharp-crested contraction devices is modeled using the dimensional analysis and the incomplete self-similarity condition. The proposed theoretical stage-discharge relationship is tested using measurements available in the literature. The proposed power equation is characterized by a value of the exponent close to 1.5 and a coefficient depending on the contraction ratio. The proposed flow-measuring flumes are characterized by a good accuracy of the measured discharge (ranging from -2.71 to 3.28% for the broad-crested co…
Measuring Rainfall Kinetic Power in Two Sicilian Experimental Areas by Drop-Size Distribution Data
The rainfall kinetic energy, which affects soil erosion processes, can be calculated by the drop-size distribution (DSD) and falling velocity. This study presents the outcomes derived by the DSDs recorded with the same optical disdrometer in two experimental areas, located in Sicily (southern Italy). Specifically, the DSDs were recorded from March 2017 to December 2019 at Sparacia and from June 2006 to April 2014 at Palermo. The aims of this paper are both to compare the DSDs for the two sites and to evaluate the applicability of Gamma theoretical distribution. Moreover, the relations of rainfall kinetic power vs. rainfall intensity are assessed. Differences in DSDs, especially for rainfall…
Establishing a threshold for rainfall‐induced landslides by a kinetic energy–duration relationship
Many investigators have attempted to define the threshold of landslide failure, that is, the level of the selected climatic variable above which a rainfall-induced landslide occurs. Intensity–duration (I–d) relationships are the most common type of empirical thresholds proposed in the literature for predicting landslide occurrence induced by rainfall. Recent studies propose the use of the kinetic power per unit volume of rainfall (J m−2 mm−1) to quantify the threshold of landslides induced by rainfall. In this paper, the relationship between rainfall duration and kinetic power corresponding to landslides triggered by rain was used to propose a new approach to define the threshold for predic…
Verifica delle equazioni disponibili per la stima della potenza cinetica delle precipitazioni naturali
Nella memoria sono riportati i risultati delle indagini condotte utilizzando le distribuzioni dimensionali delle gocce di pioggia (DSD) rilevate mediante un disdrometro ottico installato, nel periodo Giugno 2006 - Marzo 2014, presso il Dipartimento di Scienze Agrarie e Forestali dell’Università degli Studi di Palermo e nel periodo Luglio 2015-Gennaio 2016 presso la stazione sperimentale di El Teularet in Spagna. Dopo aver aggregato le DSD per classi di intensità differenti in ampiezza, è stata determinata la potenza cinetica associando a ciascun diametro della DSD aggregata la relativa velocità di caduta calcolata mediante una relazione reperita in letteratura. I valori di potenza cinetica …
Characterizing rainfall erosivity by kinetic power-Median volume diameter relationship
Abstract Kinetic power, i.e. kinetic energy per unit time and area, is the variable widely used to represent the rainfall erosivity which affects soil loss and sediment yield. This paper shows the results of an experimental investigation using the raindrop size distributions (DSDs) measured by an optical disdrometer installed at the Department of Agricultural, Food and Forestry Sciences of University of Palermo in Italy (June 2006–March 2014) and at the El Teularet experimental station in Spain (July 2015–May 2016). At first an analysis of the DSDs aggregated into intensity classes is carried out, then the measured kinetic power values are determined. The aggregated DSDs allowed to establis…
CARATTERISTICHE DIMENSIONALI ED ENERGETICHE DI PRECIPITAZIONI NATURALI MISURATE CON UNA TECNICA DISDROMETRICA IN SPAGNA
Nella memoria sono riportati i risultati ottenuti a partire dalle distribuzioni dimensionali delle gocce di pioggia (DSD) rilevate nel periodo Luglio 2015- Gennaio 2016, mediante un disdrometro ottico installato presso la stazione sperimentale “El Teularet- Sierra de Enguera” sita nella comunità Valenciana. Dopo aver aggregato le DSD per classi di intensità, è stata condotta una analisi sulle caratteristiche delle distribuzioni rilevate in funzione dell’intensità di precipitazione ed è stata verificata l’applicabilità della distribuzione di Ulbrich utilizzando il metodo dei momenti per la stima dei parametri. Le misure sono state utilizzate per determinare i valori misurati di potenza cinet…
Estimating rainfall erosivity by aggregated drop size distributions
Rainfall erosivity is defined as the potential of the rain to cause erosion, and it can be represented by rainfall kinetic power. At first in this paper, the raindrop size distributions (DSD) measured by an optical disdrometer located at Palermo in the period June 2006–March 2014 and aggregated for intensity classes, are presented. Then an analysis of raindrop size characteristics is carried out, and the reliability of Ulbrich's distribution, using both the maximum likelihood and momentum estimate parameter methods, is tested. The raindrop size measurements are used to determine the experimental rainfall kinetic power values, which are compared with the ones calculated by a theoretically de…
A method for evaluating rainfall kinetic power by a characteristic drop diameter
Abstract Empirical relationships linking kinetic energy to rainfall intensity are commonly used to estimate rainfall erosivity. In this paper, using the drop-size distribution (DSD) proposed by Marshall and Palmer, a relationship for calculating the rainfall kinetic power was firstly deduced. This equation requires the simultaneous measurement of both the median volume diameter and the rainfall intensity and its application also reveals the drawback of needing the measurement of the whole DSD by an expensive disdrometric technique. Then, using a fictitious precipitation, which is both constituted by droplets having the same diameter (mean volume diameter) and having the same volume of the a…
Predicting rainfall erosivity by momentum and kinetic energy in Mediterranean environment
Abstract Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion and it is used around the world for assessing and predicting soil loss on agricultural lands. Erosivity can be represented in terms of both rainfall momentum and kinetic energy, both calculated per unit time and area. Contrasting results on the representativeness of these two variables are available: some authors stated that momentum and kinetic energy are practically interchangeable in soil loss estimation while other found that kinetic energy is the most suitable expression of rainfall erosivity. The direct and continuous measurements of momentum and kinetic energy by a disdrometer allow als…
Estimating rainfall erosivity by aggregated drop size distributions
Rainfall erosivity is defined as the potential of the rain to cause erosion, and it can be represented by rainfall kinetic power. At first in this paper, the raindrop size distributions (DSD) measured by an optical disdrometer located at Palermo in the period June 2006–March 2014 and aggregated for intensity classes, are presented. Then an analysis of raindrop size characteristics is carried out, and the reliability of Ulbrich's distribution, using both the maximum likelihood and momentum estimate parameter methods, is tested. The raindrop size measurements are used to determine the experimental rainfall kinetic power values, which are compared with the ones calculated by a theoretically de…
Reliability of rainfall kinetic power-intensity relationships
The rainfall erosivity plays a fundamental role in water soil erosion processes and it can be expressed by its kinetic power. At first in this paper the raindrop size distributions measured, in the period June 2006- March 2014, by an optical disdrometer installed at the Department of Agricultural and Forestry Sciences of University of Palermo are aggregated into rainfall intensity classes, having different ranges, and the measured kinetic power values are determined. Measured kinetic power values are initially used for testing the applicability of the kinetic power-rainfall intensity relationships proposed by Wischmeier and Smith (1978), used in Universal Soil Loss Equation (USLE), Brown an…