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REMOTE SENSING TO EVALUATE SOIL HYDROLOGICAL STATUS IN THE ARNO BASIN, ITALY
I. Becchi, E. Caporali, F. Caparrini, G. Profeti
Dipartimento di Ingegneria Civile, Università di Firenze
Remote sensing can be a very interesting source of distributed data for large or medium scale hydrological modelling, where soil status and land conditions can be extremely different from one zone to the other and a large amount of in-situ measurement would be necessary. In this study two Landsat TM images of the lower part of the Arno basin taken in 1991 were processed using several techniques. Cluster analysis gave interesting results in monitoring the state of soil and vegetation in the two different periods of the year. Clusters obtained have been compared with the distribution of different pedological classes and soil use and with geomorphological information from the DTM. Landsat data were used also to obtain several soil water content indexes, and produce maps of soil moisture. A principal component analysis has been used to obtain data that are directly dependent on soil and the less influenced as possible by other factors like vegetation. Finally, an algorithm to retrieve soil hydraulic properties (permeability, gravitational storage, capillary storage) from geomorphological data (slope, aspect) and pedological class has been studied, using Monte Carlo simulation and optimization techniques. The spatially distributed soil hydraulic properties have been applied in a phisically based hydrological model. The results were compared with soil water content indexes obtained from Landsat data analysis on two sub-basins of the Arno river.
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