Approaches to morphological evolution in long-term morphodynamic model

PRD LTMM (long term morpho dynamic model on the Zhujiang River Delta) is a morphodynamic model representing medium-long term evolution processes of delta.Reduction approaches should be considered in a modelinput, a modeling physical system and a model out put.Representative input conditions are the base of modeling reduction, and the increase of the morphological time step is a key point of improving modeling efficiency, the most common approaches are a straight forw ard extrapo lation, a time centered extrapolation, a lengthening tide and a linearity of sediment transport.The sensitive experimentindi-cates that the PRD LTMM should adopt the lengt hening tide method to increase morphological time step, and increasing time scale is 10 a.On the basis of the approaches, the stability of PRD LTMM is very good, and its modeling precision is very high also.