Abstarct: Sedimentation and dredging have always been one of the major problems in ports and access channels that can affect port efficiency and profitability due to the high cost of the dredging operation. Therefore, considering the sedimentation rate as a determinant factor is essential and inevitable in all design stages. Accordingly, to achieve an optimal design that has the lowest sedimentation rate in the long-term, special attention must be paid to this phenomenon in the early stages of design. On the other hand, since there are many primary designs in the early stages of the design process, a fast and reliable method has to be used to calculate the sedimentation rate over the long periods. For this purpose, Van Leeuwen (2015) developed a "hybrid model" for rapid assessment of port and access channel sedimentation in long-term periods and by successful applying of the model to the Ijmuiden Port, he calculated the sedimentation rate at the port and the access channel with excellent compliance. Thus in this study, it has been tried to improve the performance of the “hybrid model” by developing a relationship between shoreline changes and sediment concentration and applying the appropriate assumptions to the Nowshahr port area. The results of applying the "improved hybrid model" to the Nowshahr port area for 20 years show that the accuracy of the "improved hybrid model" in estimating the sedimentation rate changes has dramatically increased by making a relationship between the sediment concentration and shoreline changes. Also, by using the simplifying assumptions and the appropriate relations to the conditions of the study area, the precision of the model in estimation of the sedimentation rate in the port and its access channel has been enhanced.