An innovative monitoring approach for the preventive conservation of a territorial-scale earthen fortification: the case of the Marrakech walls

Earthen architecture represents a tangible and intangible heritage of global relevance, particularly in southern Morocco, where it constitutes a key element of the built landscape and local identity. The historic medinas of Rabat, Marrakech, Fez, and Meknes, primarily built using adobe and rammed earth, attest to the long-standing construction tradition and environmental adaptability of these techniques. However, the intrinsic fragility of earthen materials, prone to physical degradation, cracking, and structural instability, necessitates the development of advanced and sustainable conservation strategies. Within this framework, a joint experimental project was launched by the École Nationale d’Architecture de Marrakech and the University of Chieti-Pescara, aimed at developing a theoretical model for the predictive maintenance of earthen structures through the integrated application of digital tools and surveying methodologies. The overarching goal is to progressively build digital twins capable of supporting real-time monitoring, structural diagnosis, and the planning of conservation interventions. The project, currently in progress, involved an initial phase of qualitative data collection based on in-situ visual surveys, experimental observations, and photographic documentation of the historic walls and monumental gates of the city of Marrakech. The collected data was used to construct simplified three-dimensional digital models designed as a basis for future refinement. The next phase will integrate quantitative data through advanced instrumentation, including 3D scanning, sensors, radar, and thermographic investigations, to accurately assess the structural behaviour and vulnerability of the heritage assets. Preliminary results highlight the validity of a progressive and integrated approach to earthen heritage conservation, combining traditional techniques, digital technologies, and multidisciplinary expertise. The creation of a shared digital data platform marks a first step toward the dynamic and sustainable management of historic structures, promoting knowledge, valorisation, and the informed transmission of this fragile yet invaluable cultural legacy.