Abstract

The analysis of the flow in rockfill materials are often fulfilled by solving differential equations that combine non-linear equation [i=mvⁿ] and continuity equation. This differential equation has first been developed by Parkin and resolving it would be by the finite difference method, proportion with restricting boundary terms at this particular case as seemed to be massive and time taking. These calculations would end up with bigger problems if they are not at the situation where the water profile isn't specified inside the rockfill material. For the analysis of the flow in rockfill material other ways can be use based on the gradually varied flow method. Calculations based on this method are simpler and more compact. The researches that have been made this paper shows that without including drag force in the gradually varied flow method would create massive errors in parts of the flow which the curvature of the flow is high. For the first time, recent studies, by the help of authors and their results of the experiments that have been taken through different rockfill materials, a rise of attention and development has been made through the influence of drag force on the water profile calculation accuracy which has been taken up by the accommodation of gradually varied flow method. The results say that with the drag force the calculation accuracy of water profile at permanent flow especially at curve level are most high, would eventually rise up and finally good results could be expected.