ERS & ENVISAT SAR : Identification of Seasonally Flooded Areas in Archaeological Contexts (Gujarat, India)
DevanthÚry, N˙ria1; C. Conesa, Francesc2; Balbo, Andrea2; Rondelli, Bernardo2; Crosseto, Michele1; Madella, Marco2
1Active Remote Sensing Unit, Institute of Geomatics, Government of Catalonia-UPC, SPAIN; 2CaSEs research group, MilÓ i Fontanals Institution, Spanish National Research Council, SPAIN
Here we present the framework and the first exploratory results of an ESA EOPI collaboration between the North Gujarat Archaeological Project (National Spanish Research Council) and the Active Remote Sensing Unit from the Institute of Geomatics (UPC-Government of Catalonia).
Optical satellite imagery and historical photography have become mainstream tools in archaeological research with increasingly improved data quality and acquisition facilities (Lasaponara and Massini 2011, Wilkinson et al. 2012). In counter tendency, SAR satellite imagery has had a minor impact despite its strong potential for the detection of archaeological structures (Di Iorio 2008, Patruno et al. 2009) and the manifold applications for understanding past archaeological landscapes in arid environments (Wiseman & El-baz, eds., 2007).
North Gujarat in north-western India is a semi-arid region characterised by:
a. A long-term archaeological record (from hunter-gatherer groups to the peripheral Indus civilization communities)
b. A fossilized landscape dominated by relict sand dunes and floodable interdunal areas.
Present day geomorphology reveals a longstanding hydrologic and edaphic variability highly influenced by the regional patterns of the Indian Summer Monsoon (ISM) and the tectonic implications of the Cambay basin. Within this actualistic scenario, the project integrates multi-scale and multi-temporal satellite imagery and geoarchaeological data for understanding settlements patterns and resource exploitation strategies in a long-term perspective.
This presentation explores the potential of ERS II and ENVISAT SAR data for addressing socio-ecological issues in archaeological contexts. The amplitude component of multi-temporal SAR images from pre-monsoon, monsoon and post-monsoonal seasons have been analysed in ENVI packages. The mean extend of floodable areas have been estimated by comparing the mean amplitude of seasonal periods. In addition, individual amplitude images from exceptional dry and wet ISM yearly averages have been evaluated for a better understanding of N. Gujarat landscape sensitivity to extreme rainfall events. The integration of SAR data and geoarchaeological data allows us to suggest a good correlation between settlement patterns and the distribution and extension of seasonal floodable areas.
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