Daqing Estuary

The Daqing Estuary opens onto the Bohai, the innermost northwestern extension of the Yellow Sea. The gulf is enclosed by Liaoning, Hebei, Tianjin, and Shandong and connects with the outer sea through the Bohai Strait. Its mean depth is about eighteen metres, and the deepest part, roughly eighty metres, lies in the northern strait. Shallow water makes the basin sensitive to the sediment and seasonal flow delivered by rivers from the surrounding land.

The present gulf rests on an older record of change. During the Pleistocene, the Bohai repeatedly advanced and retreated under shifts in global sea level; sediment cores preserve intervals when the seabed lay beneath river floodplains instead. The estuary's later geography is therefore a single stage in a much longer alternation of sea and land. Near the coast, the junction of river water and tidal basin shapes navigation and the distribution of mud. The Daqing Estuary joins inland drainage to a semi-enclosed sea whose outline has changed repeatedly over geological time.

The Bohai covers roughly seventy-seven thousand square kilometres and joins the coastal economies of four province-level regions. Its enclosed shape gives the strait particular value for movement between inner and outer waters.

The narrow entrance also controls the exchange of water and sediment between inner and outer basins.