Regarding to the desorption of the soluble matter erosion in rivers, the currently used steady-state models including Herry model, Langmuir model, Freundlich model and Surface Complexation model for predicting the desorption quantity of soluble matters were summarized. Taking Ca2+ as the representative index of soluble matters and based on the static state experimental results, the validity of the above four models were checked. The comparison indicated that because the initial occurrence of soluble matters in desorption was greatly different from it in sorption, the diffusion process in desorption was not considered in any of the above models. Then by the analysis of the desorption mode of soluble matters, it was found that the desorption was an integrated process of diffusion and ion exchange. At last, the above models were improved in which the total desorption quantity of soluble matters was devided into diffusion quantity and ion exchange quantity.
