Combining regional rainfall frequency analysis and rainfall-runoff modelling to derive frequency distributions of peak flows in ungauged basins: a proposal for Sicily region (Italy)

Abstract

Abstract. In the present study an attempt is made to provide a general Monte Carlo approach for deriving flood frequency curves in ungauged basins in Sicily region (Italy). The proposed procedure consists of (i) a regional frequency analysis of extreme rainfall series, combined with Huff curves-based synthetic hyetographs, for design storms and (ii) a rainfall-runoff model, based on the Time-Area technique, to generate synthetic hydrographs. Validation of the procedure is carried out on four gauged river basins in Sicily region (Italy), where synthetic peak flow frequency curves, obtained by simulating 1000 flood events, are compared with observed values. Results of the application reveal that the proposed Monte Carlo approach is suitable to reproduce with reasonable accuracy the hydrologic response of the investigated basins. Given its relative simplicity, the developed procedure can be easily extended to poorly gauged or ungauged basins.

Hydrological Dynamics Assessment of Basin Upstream–Downstream Linkages Under Seasonal Climate Variability

“…Rainfall heterogeneity obviously needs to be considered in a number of hydrological process studies in larger catchments area since it influences: infiltration dynamics, hydrograph regime, runoff volume, and peak flow (Bonaccorso et al 2017;Fanelli et al 2017;Gao et al 2019;Tarasova et al 2018). However, some hydrology studies still rely on small numbers of synoptic-scale rainfall measurements, and the problem of limited rainfall gauges is common in many watershed investigations, especially in developing countries (Birhanu et al 2019;Liu et al 2017;Moges et al 2018).…”

Generation of Sub-Hourly Rainfall Events through a Point Stochastic Rainfall Model

“…The simulation of sub-hourly rainfall events is an important field of hydrological research [1,2], being mainly useful for, e.g., designing water control structures in urban areas or urban drainage systems, and for flood frequency evaluations in small natural catchments, characterized by rapid hydrological response [3,4].…”

Flood and landslide warning based on rainfall thresholds and soil moisture indexes: the HEWS (Hydrohazards Early Warning System) for Sicily

“…The results are strongly influenced by both the adopted model structure and the input hyetograph shape. In order to overcome the limitation due to the lack of sufficient records to produce statistically meaningfully results, synthetic events are generated, totally stochastic for duration and total rainfall, but with well defined hyetograph shapes derived on the basis of the available historical records (Bonaccorso et al, 2017). When synthetic rainfall is generated, for each duration of rainfall, the code provides several pairs of discharge-height values.…”

“…In particular, a return period to correspond respectively with 5 (ordinary condition), 10 (moderate risk condition) and 20 (high risk condition) years was chosen for each critical level considered. These values have been determined following the approach proposed by Bonaccorso et al (2017).…”

“…relationship between flood quantiles and related return periods) for estimating the discharge correspondent to the selected return periods. The procedure applied for deriving FFC is based on a combination of statistical methods for deriving the design storms and simulation techniques, through a rainfall-runoff model, to generate synthetic hydrographs (Bonaccorso et al, 2017).…”