Gasparetto-Stori, Giuseppe

Digital Elevation Models (DEMs) of flat lowlying coastlands are becoming even more important for environmental risk analyses, for example the development of effective plans for flooding protection. The need of information at high spatial resolution over very large areas, of the order of 100×100 km2, practically precludes the use of traditional methods (e.g., leveling and DGPS) due to their intrinsic limitation in covering wide zones and reduces the possibility of using Lidar because of its high cost. Starting from the last decade, space-borne radar sensors have been used extensively for this purpose. The most known is the SRTM (Shuttle Radar Topographic Mission) DEM which covers most of the land area between ±60° latitude. This DEM was generated using singlepass interferometry and is widely available at 3-arc-seconds. In this work, we present the results obtained for the Veneto plain, Italy, using the spaceborne SAR (Synthetic Aperture Radar) crossinterferometry.

Abstract. The Venice Lagoon is characterized by a fast morphodynamics appreciable not only over the geological scale but also in historical and modern times. The lagoon environment proves very sensitive to even minor modifications of the natural and anthropogenic controlling factors. An important human endeavor accomplished in the past century is the reclamation of the southernmost lagoon area that has been turned into a fertile farmland. The reclaimed soil is reach in organic matter (peat) that may oxidize with release of carbon dioxide to the atmosphere. The continuous loss of carbon is causing a pronounced settlement of the farmland that lies below the present sea/lagoon level. This enhances the flood hazard and impacts noticeably on the maintenance and operational costs of the drainage system. Total peatland subsidence is estimated at 1.5 m over the last 70 years with a current rate of 1.5-2 cm/year. The geochemical reaction is primarily controlled by soil water content and temperature, and is much influenced by agricultural practices, crop rotation, and depth to the water table. A small (24 km2) controlled catchment located in the area has been instrumented for accurately monitoring the basic parameters and recording the ground motion. The in situ measurements have been integrated with the combined use of remote sensing data to help cast light on the process and identify the mitigation strategies.