Salt Marsh Vertical Accretion Equilibrium

Salt marshes survive sea-level rise not by staying still but by building upward — trapping mineral sediment and accumulating their own dead roots and stems fast enough to keep the platform in the tidal window where marsh plants can grow. This simulator renders a tidal marsh as a grid of surface patches, each following the Morris et al. marsh-equilibrium model: vertical accretion rises with how deeply a patch is flooded at high tide, up to an optimum, then falls off as flooding gets excessive. Push the sea-level rise slider past what the current sediment supply can sustain and watch the negative feedback fail — patches fall behind, flood deeper every year, and convert one by one into drowned mudflat, exactly the collapse mechanism used in real coastal-wetland vulnerability models.