Salt Intrusion as a Function of Estuary Length in Periodically Weakly Stratified Estuaries

Estuarine salt intrusion greatly threatens freshwater supply in surrounding lands. Physical barriers, which reduce the estuary length (L), are widely constructed to control intrusion. Yet, role of L remains unknown. Using a process-based, idealized, semi-analytical three-dimensional model, we systematically investigate for first time this unknown tide-dominated, periodically weakly stratified estuaries. Results show decreasing significantly reduces salinities short estuaries (L < Lw/4, with Lw dominant tidal wavelength), but not long Tidal pumping key importer most estuaries, regardless L. However, substantial decreases relative Lw/4 can change landward from horizontal diffusion. The latter, together gravitational circulation, weakens responses changes and river forcing This study highlights importance considering understanding mitigating