Hydrography and flow at the entrance of Alvarado Coastal Lagoon, Mexico

The purpose of this paper is to exhibit the transient and residual signal of stratification and observed flow at the entrance of Alvarado Lagoon. This Lagoon has a free connection to the sea and it is exposed to microtidal conditions and fluvial/rain bimodal discharge. Temperature, salinity and flow data, collected in two 24 hr campaigns, under different fluvial discharge, were analyzed. According to the stratification parameter value (Sp > 1) and estuarine Richardson number value (RiE > 4), the entrance of Alvarado Lagoon behaves as a saltwedge estuary and is mainly governed by fluvial discharge. The residual flow is dominated by the gravitational circulation in the dry season, and by the fluvial discharge in the rainy season. For both fluvial discharge conditions, the subtidal salinity profiles show strong stratification (Sp >1).