The influence of catchment changes on river deltas is an issue of global importance. As far as the Changjiang River is concerned, the fluvial sediment discharge has been decreasing since the early 1980s in response to catchment human activities, which results in significant sedimentological and geomorphological changes over the deltaic areas. In the present contribution, some research topics are proposed on the basis of a review of the progress made in recent years. In terms of geomorphology, bathymetric changes and coastal accretion/erosion patterns indicate that the sediment discharge is now below the critical quantity for the maintenance of the delta, i.e., the delta has reached an eoroding stage. Analysis carried out in the present study demonstrates that the critical value on the basis of chart comparison and localized deposition rate measurements is actually underestimated. For the entire subaqueous delta, accurate calculations for the critical value will depend upon a sound understanding of the sediment retention of the deltaic system. Moreover, it would be appropriate to consider two critical discharges, one for the maintenance of the delta volume, and the other for the maintenance of the surface area of the delta on land. In sedimentology, sediment cores collected from the depocentre of the subaqueous delta show a trend of decrease in accretion rate over the last 30 years, representing the effect of catchment sediment discharge changes. In the future, analysis of the sediment samples from the entire sub-aqueous delta will be beneficial to an improved understanding of the deltaic response to the cathcment changes. At the same time, such a data set will be useful for the study of the sediment retention index and the material cycling patterns (e.g. carbon cycling) over the estuarine waters. Furthermore, in order to improve the interpretation of the deltaic sedimentary record, e.g., to identify climate and environmental changes using the record, the various parameters derived from analyses of the cores should be standardized by evaluating the temporal changes caused by early diagenesis and decay, and by determining the rate of deltaic shoreline changes which control the relative position of the record within the deltaic sedimentary system.