Hydraulic and urban management during Roman times based on GIS and remote sensing analysis (Clunia, Spain)

Abstract

The Roman city of Clunia (nowadays at the spanish province of Burgos) became the capital of the Tarraconensis conventus with the Augustan provincial reform, which provided a major boost for its urban development. The suitability of the city's location is evident by the fact it was built on a plateau concealing an underground karst cave that provided direct access to water without requiring major engineering works. The waters in this cave were used and administered by the people, and some of its galleries acted as a shrine for worshipping. This study provides an overview of the modern drainage systems in order to study more profoundly the forms of urban organization, on which we have only partial knowledge currently, given the breadth of the field. We believe that some of these drains are actually tracks of ancient streets that have been fossilized in orography. To reach these conclusions, we analysed several IR photographs, and applied hydrological GIS functions to observe the path of these tracks and their relationship to what is currently known of the city's urban layout. This analysis of the surface was completed by relating it to the karst topography by conducting geophysical surveys in areas where wells giving access to the cave were detected using radiolocation. Finally, we applied a range of hydrological GIS functions and indexes on a high-resolution DEM, obtained from LIDAR technology (5 m/pixel), to confirm how the drainage worked. The results have highlighted landforms on the plateau, providing new hypotheses about Clunia's urban development. Repetitive modulations were also observed in the distances between some of the drains, thus making for a better understanding of the characteristics of an entire sector of the ancient city. We therefore believe that the drainage calculation method may be a useful tool for the study of urban structures that have not been excavated yet.

Following the Roman Army between the Southern Foothills of the Cantabrian Mountains and the Northern Plains of Castile and León (North of Spain): Archaeological Applications of Remote Sensing and Geospatial Tools

“…We also explored multispectral imagery using the datasets from the PNOA series and different spectral bands [114]. The combined use of RGB and NIR bands, allowed us to highlight the visibility of archaeological features through the calculation of vegetation indexes-such as NDVI (Normalised Difference Vegetation Index)-or image statistics like PCA (Principal Component Analysis) [115,116].…”

Tests with SAR Images of the PAZ Platform Applied to the Archaeological Site of Clunia (Burgos, Spain)

“…The third, Cuevas Ciegas (Figure 4c), had also been the result of a study [1,[38][39][40] both in terms of the access roads to the city from the plane, and in determining the main networks drainage of city waters towards the plane.…”

“…Therefore, what we conducted was to use the interpolation functions of SAGA, triangulation, to first generate individual images for each of the bands contained in the points, and then make a combination of them in false colour. With the resulting images, the SAGA function of principal component analysis (PCA) was applied, especially due to the good result obtained by our team when applying them in the published project on the Egyptian landscape of the Oxirrinquita nomos [12] with Worldview 2 images, and in analytics carried out in the Clunia project with SPOT multispectral images [1]. PCA is a multivariate statistical method used to reduce the dimensionality of the data resulting in the reduction of redundant information.…”

“…As mentioned, it was in this area where our team [1] had determined the presence of traces of urban organization with a N/S orientation, in this case applying other techniques and digital sources, such as SPOT-5 images. In this case, we have contrasted results of the radar image (Figure 12b) with the application of the SLRM function (Figure 12c) to the DTM obtained from the LiDAR point cloud.…”

“…This work allowed, among other results, to determine one of the aforementioned four orientations that would structure the urban organization of the city [1] (pp. 142-143).…”