Satellite Image and GIS for the Archaeological Park of Chan Chan

1.The operative project The archaeological site of Chan Chan, located along the northern coast of Peru, represents the largest mud brick pre-Columbian settlement (14 Km2) and it is characterized by three architectural typologies: the palaces or Ciudadelas, the Huacas or stepped pyramids and the intermediate architecture. Though it is inscribed in the UNESCO "List of Word Heritage" and "List of in danger Word Heritage", Chan Chan is suffering a dramatic process of material and urban degrade. In order to stop the process of decay the "Plan Maestro de Conservación y Manejo del Complejo Arqueológico Chan Chan" was approved by the President of the Republic of Peru in January 2000. The main objective of the plan was to integrate all the actions related to archaeological research, conservation and exploitation of the site with all the actions addressed to the promotion and the social development of its population. The MIPE (Italian Mission in Perù) has been operating in Chan Chan since 2001 following the directions of the Plan Maestro and carrying on a work of documentation and study both at the architectural and the territorial scale. The main specific goals of the project are the followings: oPlanning of the Archaeological Park of Chan Chan; oPreparing the restoration project of Palacio Rivero (one of the nine Ciudadelas); oCreation of a Documentation Centre for the planning and managing of the Archaeological Park 2.Use of Quickbird satellite images for the study of the territory The extensive settlement of Chan Chan cannot be analysed and studied without using great scale images as the high resolution ones from the Quickbird satellite (operative since 2002) used for the quantitative measurement of the deterioration and the detailed analysis of the territory. The satellite image (kindly offered by Eurimage) shows us two different factors of territorial decay due to direct anthropic activity (new paths crossing architectural structures, spontaneous vegetation, uncontrolled agriculture) and to the aggressive approaching to the archaeological area by the near town of Trujillo and its airport (Fig. 1). The comparison between the aerial zenital picture of Palacio Rivero, which was taken in the seventies by the University of Harvard, and the Quickbird satellite image (May 2003) is particularly helpful for the evaluation of the degradation process: many structures of the second sector of the palace still visible in the Harvard picture, have almost completely disappeared in the satellite image (Fig. 1). With the aim to improve the quality of the information a fusion was performed between the real colour and the panchromatic images and between the infrared and the panchromatic ones (useful for the study of soil and vegetation). The new images keep all the information of the real colour and the infrared shots but achieve the high resolution of the panchromatic one. The new images show architectural alignments which are not visible on the ground, providing therefore an important tool for the identification of buried structures (fig. 2). 3. Restoration of Palacio Rivero: geometric and photogrammetric documentation The main objective of the present project is namely to use the case study of Palacio Rivero as an example of Chan Chan architecture to create an operating model allowing the execution and relative application of IT to all the phases of documentation, research, and restoration. The geometrical survey of the palace was performed using different techniques: the Total Station for the still visible structures, the GPS for the contour lines of the surface generated by the deterioration of the walls and the aerial photogrammetry for the Plataforma de Entierro (Tomb of the King). A part of Palacio Rivero regarding the wide area of warehouses and Audiencias was recorded using the Laser Scanner Callidus CP3200 (Trimble). Following the usual procedure we have been able to create a 3D model that allows the creation of solid models from which it is possible to extract profiles, sections, elevations and all the other drawings needed for the planning of the restoration project (Fig. 3). 4.Creation of a Geographic Information System During last year we have started the construction of the GIS called "The Archaeological Park of Chan Chan" planned as a mean of managing and valorisation of the archaeological complex and of its territory. During the year 2006 the following data have been added: oCartographic data (maps at scale 1:5.000 and 1: 50.000; aerial photogrammetric survey by Harvard University of the years 1970-1973); oPhotographic data (Quickbird satellite image; aerial photos by Harvard University; aerial photo by MIPE of 2003-2005); oGeometrical data (Topographic survey with Total Station, contour lines survey with GPS of Palacio Rivero, photogrammetric survey of Plataforma de Entierro; polygonal of the archaeological area). The final objective of such a system is the gradual creation of a multidisciplinary data archive that will allow the various research and conservation activities to be updated and to schedule and implement the improvement activities, as well as to regulate the complex economic activities related to the management of the archaeological complex (tourist flow, multimedia products, constraints and integration with the modern city).