Archaeological sites in Nepal and India: Concerns of lightning risks

This study investigates the present-day lightning risks of a large number of archaeological sites in Asia, with special attention to religious monuments in South Asia with invaluable historical value. The study reveals that in most cases, no lightning protection measures (LPM) have been adopted and in several structures, LPM have been adopted but without conducting a methodical risk assessment or standard system design under experts' advice. In a majority of archaeological buildings in Nepal, appropriate lightning protection systems have not been installed, though an apparent air termination system could be observed in the form of a metallic spire or a metallic roof component. However, a system of down conductors and earth terminations has not been properly installed or not installed at all. Both the Department of archaeology and the Department of Urban Development and Building Construction (DUDBC) have not taken adequate steps to install LPS in archaeological sites fearing losing the aesthetic appearance and historical values of the structures. Appropriate LPM has not been adopted even on the structures that have been rebuilt after they were partly or fully damaged by the 2015 earthquake. In many historical structures in the southern part of India, on the other hand, partial LPM has been adopted. Even those that are designed up to the knowledge and standards that existed at the time of design, have not been maintained, and as a result, the components are most often loosely hanging or partially destroyed. Many authorities argue that concerned monuments have survived for several centuries or even over a millennium thus they do not need lightning protection. However, the environment of many such monuments is now modified with rain shelters, lighting systems, CCTVs etc., without having any LPM, thus their exposure level has been increased. However, there are no attempts made in estimating the new risk with modifications that have been done. Also, in the South Indian region, several highly significant monuments and structures have been observed to have Early Streamer Emission (ESE) devices with single down conductors. Most often, these down conductors have multiple acute bends due to the architectural topography of the building. In many such cases, the earthing system is obscured and impossible to be inspected. On such a backdrop, we propose new compulsory international or national standards or an annexure to existing standards for risk assessment, design, implementation and maintenance of LPS of archaeological structures.