Sediment budget of the Yellow River delta, China: the importance of dry bulk density and implications to understanding of sediment dispersal

Abstract

This study constructs sediment budgets for the delta of the Yellow River, one of the world’s largest muddy rivers, and, based on these budgets, discusses the characteristics and related mechanisms of sediment dispersal at the river mouth. The sediment budgets are derived from quantifying deposits in the deltaic lobe formed at the Diaokouhe mouth of the river. A detailed investigation of the dry bulk density of deposits in the delta, which yields models of dry bulk density of deposits in the main depositional settings of the delta, guarantees the reliability of the sediment budgets. Results show that deposits behind the delta front of the Diaokouhe lobe over the period of 1965 to 1974 account for 73.5% of the incoming sediment. The constructed sediment budgets reveal that the proportions of the deposits accumulated behind the delta front vary considerably over time. The main factor responsible for the variations is the change in sediment discharge of the river. There is no evidence for the anticipated positive relationships between the proportion of sediment escaping from the delta and water discharge, clay content of incoming sediment, or mouth channel efficiency. The characteristics of sediment dispersal on the delta are related to the rapid extinction of sediment-charged hyperpycnal underflows, which are dominant in the plumes off the Yellow River mouth, and sediment deposition in the overbank flow on the delta plain because both of these processes trap a higher proportion of sediment at a higher sediment discharge.