Characteristics of Water Exchange Capacity Changes in Qilihai Lagoon in the Recent Hundred Years

Abstract:

In this paper， MIKE21 is used to establish a two-dimensional hydrodynamic and mass transport model based on the triple nested non-structured grid and the measured data are used to verify the tide level， the current speed， and the current direction. In combination with the satellite remote sensing image data， the evolution of Qilihai Lagoon from 1950 to 2018 is simulated. The water flushing time scale is used to investigate the changing characteristics of water exchange capacity under different conditions and the results show that under natural conditions， the runoff change is more significant on water exchange capacity compared with water level changes. The opening of the tidal sluice is a key factor affecting the water exchange capacity of the lagoon. The reclamation project reduces the tide prism， but the slight reduction has a little impact on the water exchange capacity. The construction change of tidal inlet is the main factor affecting the water exchange capacity. The change of tidal inlet from bending to straight and its widening enhance the water exchange capacity of the lagoon.

Key words:lagoon;water exchange capacity;tidal sluice;numerical simulation