The flow trough the Strait of Gibraltar could be analyzed as a problem oftwo-layerhydraulic exchange between the Atlantic ocean and the Mediterranean sea. Theshallow waterequations in both layers coupled together are an important tool to simulate thisphenomenon. Inthis paper we perform an upwind schemes for hyperbolic equations based on theRoe approximateRiemann solver, to study the resulting model. The main goal assigned was topredict the locationof the interface between the two layers. Therefore the computational resultsobtained are comparedto previous results and experiments.