Modelización hidrológica e hidráulica aplicada a la estimación de la carga de fondo en cauces torrenciales corregidos (Rambla Del Cárcavo, Murcia)

Abstract

The difficulty in the obtaining of flow information in catchments without gaging station forces to the use of indirect calculation methods, based on the catchment characteristics and stream network. The methods of SCS and Temez unit hidrograph adjusted to a function gamma are applied to a fluvio-torrential catchment of Mediterranean semiarid regime affected by hydrological- forestal restoration projects: catchment of the Cárcavo “rambla” (Murcia). From environmental catchment conditions and rainfall records of a headwater SAIH station and close stations, unit hydrographs have been generated for statistical return period of 25, 50 and 100 years. Maximum daily rainfalls of near meteorological stations and the Log Pearson III method are used in this semiarid catchment. After, a flow routing model (convex method) is applied to evaluate the check dam influence on the peak discharge, according to the slope decrease. The topography of consecutive channel cross-sections, the bed granulometric analysis and roughness estimation allow to transform, using the HEC-RAS program, the values of peak discharge into maximum hydraulic depth. Once obtained the values corresponding to the average hydraulic radius for each cross-section and return period, downstream from several check dams, respective potential bedload transport rates are calculated by means of theoretical equations (Duboys, Meyer-Peter and Einstein-Brown). Results will allow to explain the present check dam effects on the bedload capacity during critical torrential events comparable to floods with return period t G 100 years.