Imaging spectrometry for submerged vegetation mapping in Lake Garda

Abstract

Early results of an investigation carried out in Lake Garda, Italy for mapping submerged vegetation, by means of ground-based and aerial hyperspectral radiometry in the visible and near-infrared, are here presented. Even if the lake has been recently classified at the lowest limits of mesotrophy, the morphometric characteristics of its coastal zone in the southern portion and local climatic conditions allow the growth of lentic macrophytes communities, mainly Potamogeton natans, Vallinsneria spiralis and Lagarosiphon major. Then, the knowledge of the spatial distribution of macrophytes is of primary importance also because these plants, being primary producers, are indicators of the water quality status, and could also give information related to the climatic change (e.g. by the Lagarosiphon major, that in despite of its tropical origin, is very well adapted to the Lake Garda sub-alpine environment). Hyperspectral remote sensing, due to high spatial/spectral resolutions, may provide suitable tool to integrate observations collected from traditional in situ surveys. An experiment was performed in July 2000, within an EU-RTD Project. Two aerial surveyes almost simultaneously were performed at a relative altitude of 15,000 feets, having onboard different imaging spectrometers: Digital Airborne Imaging Spectrometer (DAIS) 7915, Reflective Optics System Imaging Spectrometer (ROSIS), and Multispectral Infrared and Visible Imaging Spectrometer (MIVIS).