UPC's Hydraulic Department has developed the model named CARPA (Cálculo en alta resolución de propagación de avenidas), a hydrodynamic simulation model to perform flood routing computations.

CARPA has been specifically adapted for the simulation of unsteady free surface flow for one and two dimensional domains. CARPA solves the Saint Venant equations in one or two dimensions, depending on the domain discretization.

One-dimensional modelling of flood routing requires considering the river as a single line with a number of cross sections separated some distance between them. The results are mean values of hydraulic variables (depth, velocity). Two dimensional modelling requires the generation of a mesh representing the terrain. CARPA uses indistinctly triangular or quadrilateral unstructured or structured meshes. CARPA allows simultaneous 1D and 2D simulation, discretising different regions of the area of interest according to its topographic characteristics and expected patterns of flow. The reason of not considering the whole area of interest as a 2D domain is the possibility of greatly reducing information costs and computing time.

The numerical scheme used for flood propagation is explicit and uses a domain discretization in finite volumes, which means that the results are obtained as averages within one volume (reach in 1D, mesh cell in 2D) and not at sections or mesh nodes. Saint Venant equations allow the modeling of flood propagation in rivers but also overland flow in floodplains, cities, etc. 2D Saint Venant equations are obtained from Navier Stokes equations, once mean variables are considered to account for turbulence (Reynolds equations) and then depth averaging is performed.

References

• Bladé, E; Gómez, M.. (2006). Modelación del flujo en lámina libre sobre cauces naturales. Análisis integrado en una y dos dimensiones. 1 ed. Barcelona: CIMNE. 227 p. ISBN: 84-95999-98-6
• Oñate, E; Piazzese, J; Dolz, J;Gómez. M; Bladé, E.. (2005). Decision Support System for Risk Assessement and Management of Floods. 1 ed. Barcelona: CIMNE. 115 p. ISBN: 84-95999-75-7
• Blade I Castellet, Ernest (2005). Modelación del flujo en lámina libre sobre cauces naturales. Análisis integrado con esquemas en volúmenes finitos en una y dos dimensiones. GOMEZ Valentin, Manuel (director/a) . Tesi doctoral. Departament d'Enginyeria Hidràulica, Marítima i Ambiental. UPC