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Erosion is an exogenous phenomenon, antagonistic to the constructive forces both of an endogenous nature (i.e. orogeny) and of a biological nature (i.e. coral reef), leading to the dismantling of the earth's surface and filling, with the clastic material produced, sedimentary basins and depressions in order to level differences in altitude [1]. It is estimated that, in Europe, 25 million hectares of soil are subject to "accelerated erosion processes" [2] and that, in several areas, the magnitude of soil loss is around a few tens of tons per year. Approximately 77% of Italy is at risk of accelerated erosion [3], also due to the lack of conservative measures for soil (hydraulic-agrarian measures, drainage, grassing, etc.). The phenomenon takes on particular importance in cultivated areas, where drastic changes have been imposed in soil use and sometimes, instead of natural and stable land cover, bare soil is subject to erosive agents. In this paper, the erosivity density approach introduced in Revised Universal Soil Loss Equation 2 (RUSLE2 [4]), will be used to develop monthly erosivity maps for the Lazio region (in central Italy). This was achieved through a full investigation carried out on the monthly (Pmd), daily (P24h) and sub-daily (15-minute time-scale, P15) precipitation amounts available from rain gauges deployed across the study area. [ABSTRACT FROM AUTHOR]

A proper study of high intensity precipitation allows a reduction of the uncertainty in the estimation of the return period of the extreme rainfall, useful for hydraulic works design and for the management of hydrological risk. Because of the intrinsic uncertainty of the rainfall phenomena, it is necessary to adopt a probabilistic approach based on the definition of a theoretical probability distribution that can adequately describes observed data. Nevertheless, a recurring problem, concerns the presence of missing values and the discontinuity of the rainfall recorded data. Therefore, it is important to evaluate when an empirical sample can be considered reliable for an objective estimation of the return period associated to an extreme event. In this paper we used observation of annual maxima rainfall to investigate the changes in the intensity- duration-frequency (IDF) curves when varying the considered registration period length. Short duration and high intensity rainfall data recorded by eight rain gauges in Lazio region (central Italy) for the period between 1928 to 2017 are available. [ABSTRACT FROM AUTHOR]

Although it is widely recognized how the knowledge of the kinetic energy (KE) of precipitation plays a fundamental role in soil erosion studies, its direct evaluation is not widespread. As a matter of facts, direct measurements of the kinetic energy of precipitation require the use of sophisticated and expensive tools. Commonly, the following approach is used to deal with this issue, that is the indirect estimation of the kinetic energy from other most widespread measured hydrological variables (i.e rainfall intensity, I). Precipitation intensity measurements are widely available for many countries throughout world, on the other hand the challenge is therefore represented by establishing the best expression to relate the kinetic energy to the rainfall intensity. The aim of the study is to define among the KE-I expressions proposed in literature which best fits KE values calculated from potential erosive events collected by a disdrometer installed in Rome (Italy). [ABSTRACT FROM AUTHOR]

Knowing the dominant directions along which heavy daily precipitation events occur synchronously can be of great importance to better understand the spatio-temporal dynamics of rainfall. Furthermore, it can help to improve flood forecasting system. In this paper we propose a methodology based on complex network measures of Event Synchronization (ES) and Network Directionality (ND) to detect main synchronization directions of heavy daily rainfall recorded in the Lazio region (central Italy). We considered 15 rain gauges in the study area, with daily precipitation records ranging from 1951 to 2017. From the preliminary results emerged that for the case study heavy rainfall events occur simultaneously along the directions belonging to the angular sector NW-W and SE-E. [ABSTRACT FROM AUTHOR]

For the study and modeling of hydrological phenomena both in urban and rural areas, a proper estimation of the areal reduction factor (ARF) is crucial. The ARF is defined as the ratio between the average rainfall occurring on a specific area and the point rainfall. In literature there exist several methodologies to estimate this ratio, as a consequence the corresponding ARFs have different properties. Spite the importance of the topic for the definition of design rainfall events, the ARF estimation has still some open issues. Throughout the time, many authors have recognized several factors influencing the ratio between the spatial average rainfall over a specific area and the rainfall measured in a point. These factors can be related to the characteristics of the rainfall itself, to the characteristics of the catchment under study and to the data and methods used. In this paper, we investigate the influence of the return period (Tr) on ARF estimation, for heavy rainfall events observed in the Lazio Region (Italy). [ABSTRACT FROM AUTHOR]

Daily rainfall series analysis is crucial both for engineering design purposes, freshwater management and it currently used in various types of agriculture management models to evaluate the associated drought risk. More recently the studies of daily rainfall events are used to investigate changes in rainfall occurrence. A basic approach to accomplish this aim is to identify the magnitude of the events and regroup them into categories. Some studies in literature proposed a classification of daily rainfall events based on single thresholds, which are commonly defined for quite large areas. Because the location and seasonality are recognized to be influencing factors for particular precipitation regime, the reliability of classification methods based on single thresholds should be properly assessed for the different locations and time scales. In this paper an investigation on the applicability of single thresholds for daily rainfall events classification for Lazio region is presented. For the case study, results suggest that a classification based on single thresholds is not suitable and therefore the need for a different approach is required. [ABSTRACT FROM AUTHOR]

The present study aims to assess the digital elevation model (DEM) resolution influence on the peak flow estimation for the design hydrograph of a large dam. This was executed by comparing the design hydrograph peak flows, with respect to a 2000 years return period, which were estimated for the Pietrarossa dam, in the South-East of Sicily, for different DEM spatial resolutions. The methodology consisted of the watershed extraction from the catchment basin in which the directly wired area belongs. Furthermore, the intensity duration frequency (IDF) curves were estimated starting from the observational time series collected by two rain gauges located near the dam. Finally, through a rainfall-runoff transformation, the design hydrographs were obtained by using both the watershed and the IDF curves. Considering different spatial resolutions, it was found that both the peak flow and the total volume decreases as the DEM spatial resolution decreases. [ABSTRACT FROM AUTHOR]

We consider the system of partial differential equations associated with the mathematical model for debris flows proposed by E.B. Pitman and L. Le (Phil. Trans. R. Soc. A, 363, 1573–1601, 2005) and analyze the problem of the hyperbolicity of the model. [ABSTRACT FROM AUTHOR]