Estimation of synthetic flood design hydrographs using a distributedudrainfall–runoff model coupled with a copula-based single stormudrainfall generator

摘要

In this paper a procedure to derive synthetic flooduddesign hydrographs (SFDH) using a bivariate representationudof rainfall forcing (rainfall duration and intensity) via copulas,udwhich describes and models the correlation between twoudvariables independently of the marginal laws involved, coupledudwith a distributed rainfall–runoff model, is presented.udRainfall–runoff modelling (R–R modelling) for estimatingudthe hydrological response at the outlet of a catchment wasudperformed by using a conceptual fully distributed procedureudbased on the Soil Conservation Service – Curve Numberudmethod as an excess rainfall model and on a distributed unitudhydrograph with climatic dependencies for the flow routing.udTravel time computation, based on the distributed unit hydrographuddefinition, was performed by implementing a procedureudbased on flow paths, determined from a digital elevationudmodel (DEM) and roughness parameters obtained fromuddistributed geographical information. In order to estimate theudprimary return period of the SFDH, which provides the probabilityudof occurrence of a hydrograph flood, peaks and flowudvolumes obtained through R–R modelling were treated statisticallyudusing copulas. Finally, the shapes of hydrographsudhave been generated on the basis of historically significantudflood events, via cluster analysis.udAn application of the procedure described above has beenudcarried out and results presented for the case study of theudImera catchment in Sicily, Italy.