Dynamic response of the Yellow River estuarine sandspit to new water and sediment regimes

The estuarine sandspit is in the river-sea interaction zone, where it shows fast responses to changes in water and sediment volumes.High-resolution satellite and hydrological data were used to analyze the current Yellow River water and sediment regime and the evolution of the estuarine sandspit.The results show that: ① The water and sediment input into the sea have continuously decreased since 1999, and its transport has changed from linear to periodic fluctuations, with a fluctuation period of 6—8 a.It is in a rising period from 2018 to 2021.From 2018 to 2021, the water and sediment input have increased.② Since 2018, the northern and eastern branches of the estuarine sandspit have alternately become the main body of siltation with an average river extension length of 0.7 km, and an average land creation zone of the sandspit with an area of 16.9 km².③ Even though less water and sediment entering the delta are not conducive to the seaward deposition of the delta, the area of estuarine the sandspit will still increase due to the strong sediment transport into the sea brought on by extreme runoff.④ The branching pattern slows down along the length of the river extension, but the land creation in sandspit is speeding up.These factors positively affect the long-term stability of the Qingshui channel.However, it is not conducive to the ecological security of the estuary wetland.