Abstract
Parameters in the lumped sedimentation formula rating curve Q~s~ = KQ^P^ are discussed to estimate sedimentation in a basin without calibration in that basin. We were unable to determine the physical meaning of the parameters that are widely used by many researchers. A physically based sediment equation, the Itakura–Kishi equation, prepares a numerical experiment system to discuss rating‐curve parameter characteristics. Experimental results suggest a method to estimate K and P parameters from geomorphologic data, particle diameter, riverbed slope, and roughness by changing experimental conditions. The results yield P from the particle diameter and riverbed gradient, and K from the exponential function of the gradient, particle diameter and roughness. Both the proposed rating curve and the Itakura–Kishi methods are applied to the Mekong River basin combining with the BTOP‐MC (block‐wise TOP model with Muskingum–Cunge routing) model, a distributed hydrologic model, to discuss estimations and their characteristics in practical fields. The proposed methods for K and P provide good agreement with mainstream data from the Mekong River under conditions of gradual water‐level variation. Copyright © 2005 John Wiley & Sons, Ltd.