Conservation of andalusian monumental heritage: the case study of the Niebla walls in Spain

Abstract

The conservation process through interventions in a building requires adequate prior expert opinion. The diagnosis and subsequent safety assessment - raised in ICOMOS guidelines - are suitable mechanisms for the study of a heritage structure. Diagnosis involves a historical analysis of the past, as a tool to predict future responses; qualitative analysis determines the deterioration and the origin of the pathological process; and quantitative analysis characterizes components by observations and experimental measurements. However, in the short or medium term ineffective decisions might be taken if assessing the state of a building using only the aforementioned tools.The Declaration of Assisi (ISCARSAH, 2000) stresses the need for prevention and the successful management of a risk-prevention program. By completing all assessment reports, in addition to a suitable risk assessment focused on the intervention and design of appropriate preventive measures, ensures a reduction in the vulnerability of a structure by managing a significant improvement in durability and, therefore, the sustainability of conservation and maintenance processes.In order to verify such vulnerability of different degrees of interventions (comprehensive, partial, or none), the Almohad rammed earth walls of Niebla, Huelva, Spain was considered as a representative case study. It is almost 2-km long and includes 47 towers. The fortification complex currently has heterogeneous characteristics, although an almost entirely uniform appearance has been maintained. Since 1980, there have been several restorations that, from the beginning, reflect mixed results over time. Based on the results of an assessment, current circumstances and risks, a diagnosis was made in order to design and prioritize preventive and corrective measures that will permit greater durability of the walls of Niebla