Multiple Inflows Muskingum Routing Model

The Muskingum principle of flood routing is applicable to a single channel reach bounded by two measuring sections with no lateral inflow in the reach. The basic Muskingum model provides a forecasting form that may be used to predict the downstream flow, a finite time ahead on the basis of the current flow rates. To apply the Muskingum principle to a channel network having inflows from different subcatchments that join downstream to form a combined outflow, the inflows from the subcatchments may be substituted by an equivalent single inflow for an ideal Muskingum reach. This paper proposes a new multiple inflows Muskingum model; the parameters in the model can be estimated using channel properties, the model may be used for routing in ungauged river networks. The new model appropriately extends the Muskingum philosophy to multiple inflows routing and can be expressed in single inflow-single outflow form; a Muskingum-Cunge model and forecasting model for multiple inflows similar to the basic model can be defined. The multiple inflows single outflow forecasting model is simple with easy calculations, and permits prediction of common downstream outflow a finite time ahead, using the concurrent flow rates observed at different gauging stations. The model performance is compared with the nonlinear kinematic wave model. Application of the model to the flood events in Narmada Basin, in India, shows that the model performance is satisfactory.