Environmental geology of the Miramichi Estuary: physical oceanography

The Miramichi Estuary system consists of Inner Bay and the river estuary, each behaving differently under changing rates of freshwater inflow. In the river estuary, higher inflow rates intensify the halocline, with little effect on bottom salinities, whereas Inner Bay water is diluted almost equally throughout the water column. Increased freshwater inflow increased ebb currents in the river estuary, while the flood currents remain relatively unchanged. Under extremely high inflow the two layer estuarine flow may not exist in the river estuary and the residual currents may beebb directed throughout the water column. The tidal and nontidal variabilities of salinity are comparable in the restricted channels, but the nontidal variability is greater in the open Inner Bay. For currents, the two scales of variability are comparable in Inner Bay, but tidal variability is greater in the restricted channels. The circulation in Inner Bay is cyclonic, but may be reversed to anti-cyclonic during periods of high freshwater inflow. The total flushing time rages from 43 tide cycles for a low inflow of 150 m3 s to 17 tide cycles for a high inflow of 1250 m 3 s during the spring freshet.