Reliable Soil Property Maps over Large Areas: A Case Study in Central Italy

Abstract

In this article we present results of a data collection project carried out to create a reliable georeferenced database to characterize the soil types constituting the near surface cover of study areas located in central Italy. The database includes the following features: i) the coordinates of the site investigations; ii) the geotechnical parameters; iii) the shear wave velocity in the upper 30 m of soil; iv) the type of test used to evaluate the geotechnical parameters and the shear wave velocity; and v) the general description of the stratigraphy. Preliminary analyses on the data were performed to determine the average values, the distribution of the measured data over the intervals, and the probability density function that best fits the measured values. Secondly, geostatistical analyses were done to assess the spatial correlation between data. Among the soils considered, only gravels show a low correspondence between the experimental variograms and the mathematical curve fitting them, while for all of the other soils, such agreement is high. Finally, two applications of the newly developed database are proposed. The first one is the development of continuous soil property maps for a selected study area, created from the information included in the database, which is constrained by a discrete amount of information. In the second application approximately the 80 percent of the measured data are considered to provide spatial predictions, which are tested with the remaining 20 percent of the data.