Valeria Montesarchio

Long term discharge simulation through a geomorphological model

Flow duration curve estimation must be performed on the basis of continuous rainfall-runoff simulations. In ungauged basins, a under-parameterised model is needed to reduce the uncertainty of the results. In this paper a geomorphological model based on a width function (WFIUH) was used to simulate low flows in a mean-sized basin in Central Italy. The WFIUH model [9]introduces a new approachto the curvenumber method and was used to evaluate the stream-flow for hourly event representation. The aim of this work is to evaluate the behaviour of the WFIUH model for long term simulation and then to compare the standard curve number approach to the curve number method implemented in the WFIUH model. To predict the behaviour of catchments for a long term, to know the response of catchments in different seasons or in different years, it is necessary to improve the model and to identify a new method for calculating base-flow. To obtain these results, it is necessary to separate base-flow and stream-flow, simulate the two contributions and build a unique series of values that reproduces the answer of the basin to different rainfalls during the year to estimate the low flow during a dry period. The model can also be used in ungauged basins because a unique parameter is used.

IDF relationships for short duration rainfall

The intensity-duration-frequency (IDF) relationships bound rainfall intensity to duration and return period. These relationships are commonly used as an input in design of many hydraulic structures and drainage systems. Empirical IDF are estimated on the basis of recorded maximum annual precipitation of given durations, often ranging from 1 h to 24 h. For shorter durations, extrapolations are applied. In this paper, maximum annual precipitation for durations shorter than 1 h (namely, 30 min and 10 min) are evaluated using a rainfall disaggregation model and then used for the evaluation of the IDF relationship. A comparison of values obtained with the extrapolated values is then performed, and the results are discussed. Keywords: intensity-duration-frequency curves, rainfall disaggregation, entropy.

A comparison of two rainfall disaggregation models

Whitin the context of flood management, and generally for performing environmental, climate, hydrological, and water resources analysis, it is useful and reliable to provide scenarios by rainfall simulation, in order to overcome data limitations in terms of time and spatial resolution. Generally, it is required that the stochastic model preservesimportant properties of the rainfall process, such as intermittency, seasonality and scaling behavior in space and time, so that there will be no substantial differences between historical rainfall data and synthetic records. In this work, two rainfall disaggregation models are evaluated in terms of their ability to reproduce rainfall hourly statistics in four sites in Central Italy. The considered models are an entropy based disaggregation model and Hyetos-R (Bartlett-Lewis rectangular pulses rainfall)

A preliminary analysis of rainfall spatial distribution at catchment scale

This study aims to develop a preliminary analysis, examining different aspects of the spatial variability of rainfall at catchment scale, in order to assess some general conclusions by examining the relationships between the different monitoring stations and to identify and highlight evident correlation anomalies. In particular, we will analyze the following aspects: the trends of cumulative rainfall on an annual and seasonal (spring / summer and autumn / winter) basis; the identification of flood events based on available flow data; the identification of significant rainfall events; the analysis of the rainfall measured in each station at event scale and the presence of any relationship between the spatial variability of precipitation events with the distance between the stations, the distance from the sea and the difference in station elevations.

Evaluation of optimal rain gauge network density for rainfall-runoff modelling

The hydrological significance of the rainfall time-space distribution on a flood hydrograph is well known and assessed in literature. The density of the rain gauge network and the pattern of areal and temporal distribution of rainfall can affect the results of the calibration and the validation of distributed rainfall-runoff modeling. The aim of this work is to assess the implications of changing the composition of rain gauge network, successively reducing the number of gauging stations, while maximizing the performance of the hydrological model. This case study is based on the Mignone river basin (500 km2), which is located in Central Italy and equipped with 4 rain gauges.