Tidal landforms, patterns of halophytic vegetation and the fate of the lagoon of Venice

We review recent advances in the study of tidal landforms and their embedded vegetation patterns within the lagoon of Venice, aiming at clues on the coevolution of their morphodynamic and ecological features. The observation and analysis of network and vegetation patterns in a tidal environment, from accurate topographic surveys and remote sensing, provide significant insight both into the hydrodynamic regimes and the interactions of geomorphic and ecological processes. A dynamically based procedure for watershed delineation may be introduced which identifies the 'divides' for every subnetwork, and allows the objective study of the parts and the whole, in particular the network. Techniques for the study of channel meandering through the objective identification of their geometric properties are also reviewed and discussed. Mapping of halophytic vegetation from remote sensing and analyses of its spatial patterns are also discussed. Links between vegetation patterns and geomorphic features indicate an important role of vegetation in the dynamics of tidal marshes. We suggest that the great diversity exhibited by the residual tidal landforms in the Venice lagoon stems from pronounced spatial gradients of landscape-forming hydrodynamics and from the imprinting of several crossovers related to competing eco-geomorphic processes. We also rationalize the observed variability, in particular of marsh vegetation patterns, and indicate links with interacting geomorphic processes - and thus we supposedly provide elements for the prediction of the morphological fate of the Venice lagoon. © 2004 Elsevier B.V. All rights reserved.