Numerical Study on the Influences of Hydrodynamic Factors on Water Age in the Liao River Estuary, China

The concept of water age (WA) is applied to the Liao River Estuary to estimate the timescale quantifying transport processes. A series of numerical experiments under different hydrodynamic conditions based on a real-time calibrated three-dimensional model have been conducted to investigate the influences of runoff, tide and wind on WA distribution. The model result shows that the WA distribution in a real situation can be estimated roughly by the real-time monitoring runoff with a natural logarithmic function. The influences of tide on WA distribution in the river channel and outside the mouth of estuary are reverse. The variation of tidal forcing affects the fluctuation range of WA in a semidiurnal tidal cycle. The wind-induced estuarine circulation as well as the WA distribution is varied significantly under different seasonal winds. In addition, the vertical difference of WA is more pronounced during neap tide in the rainy season, and it is reduced under wind conditions.