A Combined Use of GPR Data With Historical Archives for Identifying Pavement Construction Periods of Valencian Silos (16th Century, Spain)

Abstract

This paper describes the combined use of ground penetrating radar (GPR) data with historical archives performed in the silo-yard of Valencia (Spain) to identify and map various pavement construction periods. The Valencian silos were constructed to house the underground grain storage of Valencia City. This architectural complex is composed of three buildings and a big square (silo-yard), under which 41 silos are placed. The construction of the silo-yard pavement extended for two centuries (16-18th century) following different construction systems. Historical archives confirmed seven pavement construction periods. However, archive data provided scant information on pavement layers and the construction periods. A GPR survey was carried out for pinpointing the seven pavement construction periods. A GSSI SIR-3000 equipment with a 400-MHz frequency antenna was used for collecting ${1} \times {1}\;\text{m}$ grid $- {141}$ profiles across the square (${5110}\;{\text{m}^{2}}$), reaching 1.5-m depth. In addition, a GPS survey was performed specifically for surface mapping the silo-yard in detail. The combined use of the GPR data (2-D reflection profiles, spectra, and amplitude slice maps) with the historical archives allowed identifying and delineating the different pavement construction periods on the silo-yard map in terms of materials and thicknesses. These results demonstrate GPR is a noninvasive and nondestructive technique for mapping soils and near surface horizons. Additionally, the combined use of the GPR data with the historical documentation makes this technique even more efficient for the comprehension of shallow ground layers, especially in cultural heritage studies.