Subsidence due to peatland oxidation in the Venice Lagoon catchment

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.Published81-906A. Monitoraggio ambientale, sicurezza e territorioope

The ISES Project subsidence monitoring of the catchment basin south of the Venice Lagoon (Italy)

The catchment located south of the Venice Lagoon experienced during the last century a general land settlement owing to groundwater pumping, oxidation of organically rich soils enhanced by agricultural activities, and natural sediment compaction. High land subsidence rates (2-4 cm/year) have been estimated in the area comprised between the lagoon edge and the Adige River and located between two leveling lines of the Italian national network (IGM lines n 7 and n 19). Only a partial knowledge on the behavior of land elevation is available in this region. To overcome this lack of information, a new fine leveling and GPS network has been established in the area within the ISES Project funded by National/Local water and administrative Authorities. The first field measurement carried out in 1999 have produced as a major result an accurate knowledge of the geoid height in this part of the Po River plain and has pointed out the stability of the area located along the lagoon boundaries during the six-year period from 1993 to now

Subsidence due to peat oxidation and impact on drainage infrastructures in a farmland catchment south of the Venice Lagoon

Large agricultural areas reclaimed in the past century, south of the Venice Lagoon, have experienced significant land subsidence due to oxidation of peat organic soils. This has exposed the region to flood hazard particularly during severe storms and has contributed to increase the marginal management cost of the infrastructures (ditches, levees, pumping stations) designed to operate the drainage system. Direct measurements and indirect evidence from the channel network suggest a land settlement between 1.5 and 2 m over the past 70 years. This paper provides an overview of the problem with important information on its most recent evolution

DEM OF THE VENETO PLAIN BY ERS2-ENVISAT CROSS-INTERFEROMETRY

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.PublishedBologna, Italy5IT. Osservazioni satellitariope