Diachronic land use analysis for the evaluation of the impact on agriculture and natural vegetation of the high-speed railway tunnel in Central Italy 1

摘要

INEA has developed a study, based on remote sensing and Geographic Information System (GIS) technologies, on the changes in land use, vegetation conditions and crop water requirements after the realisation of a tunnel in the Apennine. In fact, this tunnel has significant effects on the drainage of superficial and underground waters. The diachronic NDVI and land use analysis in 1992 and 2001 (before and after the tunnel realisation) show significant negative changes in vegetation index, and certain vulnerability of some agricultural surfaces. For a better estimation of the influence of water drainage on NDVI and to establish the exact correlation between the changes in vegetation index and lower levels of humidity in soils and in vegetation, the NDVI analysis was made on clusters of pixel corresponding to each zone of water drainage/gallery. For each drainage zone the drained volumes of water were also related to the total crop water requirements. To complete the analysis and to isolate the effects due to the gallery from a generalised reduction of NDVI in the area, an examination of the differences of the index between 1992 and 2001 in both areas (influenced and not by the gallery) was made.