RESEARCH PAPER
DESIGN HYDROGRAPH ESTIMATION IN SMALL AND UNGAUGED BASINS: A COMPARATIVE ASSESSMENT OF EVENT BASED (EBA4SUB) AND CONTINUOUS (COSMO4SUB) MODELLING APPROACHES
Andrea Petroselli 1  
,  
Salvatore Grimaldi 2  
,  
Rodolfo Piscopia 3  
,  
Flavia Tauro 2  
 
 
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1
Department of Economics, Engineering, Society and Enterprise (DEIM), University of Tuscia, Via San Camillo De Lellis snc, 01100 Viterbo, Italy
2
Department for Innovation in Biological, Agro-food and Forest systems (DIBAF), University of Tuscia, Via San Camillo de Lellis snc, 01100 Viterbo, Italy
3
Freelance, Rome, Italy.
CORRESPONDING AUTHOR
Andrea Petroselli   

Department of Economics, Engineering, Society and Enterprise (DEIM), University of Tuscia, Via San Camillo De Lellis snc, 01100 Viterbo, Italy
Publication date: 2020-03-05
Submission date: 2019-09-16
Final revision date: 2019-11-13
Acceptance date: 2019-11-13
 
Acta Sci. Pol. Formatio Circumiectus 2019;18(4):113–124
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ABSTRACT
Aim of the study:
Aim of the study is to provide a comparative assessment of event based (EBA4SUB) and continuous (COSMO4SUB) modelling approaches for rainfall-runoff modeling for small and ungauged basins, focusing on the influence of the Antecedent Moisture Condition (AMC) of the soil on the estimated design peak discharge.

Material and methods:
The event based approach is the EBA4SUB software. It consists in selecting a design rainfall event, in estimating the rainfall excess and in transforming it into the direct hydrograph. The continuous approach is the COSMO4SUB framework. It consists in generating a long synthetic rainfall time series at sub-daily resolution that feeds a continuous rainfall–runoff model. Then, a discharge time series is determined, providing the estimation of the runoff and the related peak discharge.

Results and conclusions:
Results show the critical role of antecedent moisture condition (AMC) and how subjective the event-based approach is for determining the design hydrograph and peak discharge. In the event-based approach, AMC is arbitrarily selected by the analyst, while in the continuous modelling it is automatically determined using the synthetic rainfall input. Our findings indicate that the event-based approach systematically leads to a considerable overestimation of floods if AMC III (wet soil) is assumed or to a slight underestimation of floods if AMC II (average condition for soil humidity) is selected.

ISSN:1644-0765