Dredging Volume Estimation and Dredging Timing for Waterway Maintenance: A Case Study Using a Depth-Averaged Hydrosediment–Morphodynamic Model with Transient Dredging Effects

Abstract

Dredging is an important measure for maintaining sufficiently high water depths in waterways. However, previous dredging studies have rarely focused on modeling the transient effects of dredging activities on bed evolutions. Here, the transient dredging effects are parameterized as source terms in the mass conservations of bed materials. The parameterization is implemented into an existing depth-averaged hydrosediment–morphodynamic model. This facilitates detailed numerical case studies of dredging effects in the multiple-branched Dongliu waterway in the Lower Yangtze River. The dredging volume of the Dongliu waterway is estimated using the present method and two traditional methods. It is shown that consideration of the transient dredging effects can considerably reduce uncertainty. By systematic parametric studies, a dredging timing before the low water stage is recommended. It is shown that this dredging timing has the advantage of not only avoiding operation difficulties related to high water level as well as intense back-siltation for an earlier dredging but also avoiding the risk of sudden water level drop for a later dredging.