The Muskingum-Cunge flood routing model is extended to the realm 'of looped
ratings. This is accomplished by reformulating the conventional four-point
model to use the local water surface slope and the Vedernikov number in th
e expression for hydraulic diffusivity. The developed model was successful
in generating looped ratings under a wide range of kinematic/diffusive unst
eady flow conditions. Numerical experiments were used to test the looped-ra
ting Muskingum-Cunge model. Resolution level, flood wave period, baseflow,
and peak-inflow/baseflow ratio were varied to determine loop thickness and
percentage mass conservation. Comparison of the looped-rating Muskingum-Cun
ge model with a dynamic wave model (a complete solution of the St. Venant e
quations) showed that both models are capable of generating looped ratings
and outflow hydrographs of comparable accuracy.