Bed shear stress and sediment transport equations for predicting morphological and shoreline changes: a review

Abstract Coastal sediments can be transported as bedload and suspended-load transport by waves and currents. The waves stir up the sediments, then currents transport sediments. Waves on the bottom can generate bed-shear stress. Meanwhile, the combination of bedload and suspended-load transport is known as total sediment transport. Prediction of total sediment transport has become important related to coastal morphological change and also shoreline change. Most of the sediment transport equations and approaches are developed from the physical principles. There are so many researchers proposed some formulas and methods with some considerations and difficulties. Due to the complexity of coastal conditions, the existing sediment transport rate prediction formulas are still not finished yet. Several well-known equations of bed-shear stress, bedload-suspended transport, and cross shore-longshore sediment transport; are discussed and reviewed in the present study. Thus, an overview of approaches and formulations that are reliable and nearly accurate for calculating the total sediment transport rate based on the characteristics of each coastal waters will be obtained. Accurate estimation of sediment transport rates will provide good results for predicting and monitoring changes in coastal morphology and shoreline changes. Moreover, coastal monitoring can be used for actions related to coastal protection system and coastal management.