A Value-Based Risk Assessment of Water-Related Hazards: The Archaeological Site of the Sanctuary of Asklepios at Epidaurus

Abstract

The accelerating impacts of climate change present critical challenges to cultural heritage, particularly in the Mediterranean region where hydroclimatic extremes are intensifying. Future estimates for the Sanctuary of Asklepios at Epidaurus, a UNESCO World Heritage Site, suggest more intense precipitation patterns, increased rainfall intensity and water-induced material degradation. This study aims to identify current and projected climate-related threats to the site and to inform adaptive strategies that safeguard both its physical integrity and its associated heritage values through a value-based approach. Opting for a heritage value-based risk assessment, the study employs a mixed-methods technical approach grounded in the Conceptual Framework for Disaster Risk Reduction of UNISDR and ICCROM’s “ABC Method” for the risk assessment of climatic threats that combines GIS-based hydrological modelling (HAND), field observations and existing material assessments with NARA Grids to link exposure, vulnerability and value loss. Results reveal intensified surface water runoff and localised water inundation threatening key monuments, particularly the Roman Odeion and the central part of the site’s ensemble, while frost-related risks are projected to decline towards 2100. The findings suggest the development of site-specific climate change adaptation that prioritises drainage enhancement, preventive conservation and continuous monitoring to preserve its Outstanding Universal Values under changing climatic conditions.

1. Introduction

The Mediterranean region has been characterised as a hotspot for highly interconnected climate risks with impacts affecting all human infrastructures, economies and, notably, cultural heritage [1]. Cultural heritage emerges in the discussion of climate change in its nature of being a non-renewable resource of knowledge [2], enabling identity formation through the social interpretation of past and present [3]. Recent scientific evidence demonstrates that the Mediterranean region is experiencing rapid intensification of hydroclimatic extremes profoundly affecting the integrity of archaeological sites [4]. Temperature across the region has increased at a rate substantially exceeding the global average, with projections indicating a temperature rise of 1.7 to 4.5 °C by 2100 [1], whilst precipitation patterns have become increasingly unpredictable, characterised by prolonged droughts interspersed with intense rainfall events that exceed historical events [5]. The ICOMOS Climate Action Working Group has emphasised in successive position papers and technical guidance that water-related hazards represent amongst the most pervasive yet systematically under-researched to archaeological sites across the Mediterranean basin [6,7]. This recognition stems from growing evidence that heritage sites face accelerating risks from surface runoff [8] and flooding [9] with documented cases of loss of the archaeological context at sites across the eastern Mediterranean [10]. As a result, practitioners and researchers alike struggle to predict and manage these impacts of these risks at individual locations without site-specific evidence [11].

Greece hosts 19 inscribed World Heritage Sites bearing an outstanding testimony of the past, with Peloponnese Peninsula being home to 5 of those [12]. Several of these sites have already been impacted by climate change aggravated natural disasters. From the wildfires affecting monuments of Mycenae [13] and the close encounter with the archaeological remains of Ancient Olympia [14] in 2020 and 2021, to the deterioration of the building stones of Apollon Vasses due to extreme temperature variations [15], these incidences only highlight the multiplicity of potential threats to cultural heritage. While wildfire risk has received considerable attention and has been the topic of scholarly and public interest, little specialised site-specific research is conducted to elaborate on other potential threats and their impacts, rendering heritage sites even more vulnerable to other natural disasters.

Extreme weather events including intense rainfall and snowstorms have impacted the Sanctuary of Asklepios at Epidaurus with their cascading effects like landslides having already been introduced during past events. As one of the most prestigious archaeological heritage sites in Greece, it boasts a well-preserved natural environment which accommodates all the archaeological artefacts for its complete conception [16]. It bears testimony of the evolution of medicine: from a function of a deity to its development into science [16]. As of today, the Sanctuary is more than just its past; it is a hub of cultural expression [17]. Located at the foothill of Mount Kynortio, future estimates for the region foresee more days of extreme rainfall events which will also be more intensified. Adding in the estimates of more dry days and increased desertification potential, the impacts induced by the effects of water at the core and buffer zones of the site, could become more significant, affecting the integrity and authenticity of the heritage site in the future. This study addresses the gap of knowledge in the methods of quantification of hydroclimatic impacts on cultural heritage in the face of climatic data scarcity and aims to inform targeted adaptation measures to enhance the resilience and conservation of the Sanctuary of Asklepios.

The aim of the paper is to identify the present and future effects of water flow, accumulation and ice formation in the archaeological site of Asklepios and to promote climate change adaptation measures to build resilience. It revolves around the vulnerability analysis of the archaeological site to the climatic conditions to which it is exposed to, to reveal relevant threats and subsequent impacts. Adopting a value-based approach, impacts will be quantified on the grounds of change to the ascribed heritage values to the site to inform climate change adaptation measures to build resilience.

Results of the analysis inform us that projected mid- and long-term hydroclimatic changes are likely to increase surface water runoff, soil erosion, and material weathering at the Sanctuary of Asklepios, which could in turn threaten the site’s structural stability and archaeological fabric. Notably, frost-related risks are projected to decline towards 2100, whilst water-induced threats will intensify throughout the mid and long-term future. Consequently, the study demonstrates that targeted, site-specific adaptation measures are required to safeguard the site’s integrity and values and to build resilience against the projected climatic stresses. These measures prioritise drainage enhancement, preventive conservation and continuous monitoring to preserve the Outstanding Universal Values of the sanctuary under changing climatic conditions, whilst demonstrating a replicable methodology applicable to other data scarce heritage sites facing similar cascading water-related hazards.

1.1. Climatic Indexes of the Region

The archaeological site of the Sanctuary of Asklepios is situated in Argolid, Peloponnese. The natural environment of Argolid is characterised by valley pastures and semi-mountainous fertile lands. From a geological standpoint, it is characterised by its richness in soils, hosting quarries where marble and limestone of exceptional quality had been quarried for centuries [16]. The intense relief of the terrain features multiple geological layers and contributes to the wide array of landscapes [18].

To visualise climatic changes, the Climascape project [19] and the Regional Plan for Climate Change for Peloponnese [20] (RPCCP) are jointly consulted. The high variability of natural systems and the inadequacy of present-day tools to generate high confidence regional models for future scenarios, renders the cross reference of information mandatory. Specifically, the Climascape project provides high confidence data until 2065 with more precise markers of change, but no information post-2065 [21]. This gap is filled with medium confidence regional estimations from RPCCP until 2100 and verifies claims made by the former. Overall, an increase in temperature in all seasons is expected, along with warm days and tropical nights with wind speeds exhibiting a slight increase in winter and summer.

Focusing on the findings of Climascape project for mid-future estimates, annual rainfall is expected to decline overall during all seasons from 1.310 mm/day to 1.142 mm/day with the greatest decrease expected in Spring from 1.377 mm/day to 1.130 mm/day. In detail, even if the wet days are expected to experience a decrease of 0.3 days, the rainfall index is expected to see an increase from 7.114 to 8.290, all rainfall parameters following the same trend. Specifically, the number of heavy and very heavy precipitation days are expected to increase by around 1 day. Maximum height of rainfall for both one and five consecutive days is expected to increase, from around 60 mm to 70 mm and from 83 to 107, respectively. Additionally, dry days are also seeing a rise from around 108 to 121 days and ground humidity indexes for all seasons are also expected to decline considerably. The combination of these indexes could lead to the assumption that, even though overall rainfall is expected to decline, intense rainfall events are expected to become more frequent than before. Adding to this the effects of decreased ground humidity on the degradation of the soil quality [22], there could be experienced higher levels of water runoff due to soil erosion [23]. In general, data from RPCCP for mid-future support the findings of the Climascape project, exhibiting; however, some slight deviation, potentially due to the regional scale of the study.

For the 2100 timeframe, RPCCP informs that Peloponnese is expected to experience meaningful in overall mean temperature, heatwaves, thermal discomfort days, with the occurrence of extreme phenomena expected to increase and precipitation to decrease [20]. Temperature rise is expected to be in the range of 1.7–4.5 °C and a reduction in precipitation of 15–30% with subsequent drop of 5% in humidity levels. Frost days and snow coverage are projected to experience a dramatic decrease on the alpine altitudes experiencing a decrease in freezing days by 10, reaching around 40/year in the far future, whereas regions lower than 500 m in altitude are expected to have 0 freeze days. Snow coverage follows, practically, the same trend. Summer season is expected to extend by incorporating more summer days. Focusing on altitudes lower than 500 m, days when temperature will be higher than 25 °C will reach around 150, 35 °C around 40 and above 37 °C around 25 [20].

1.2. The Sanctuary of Asklepios

The richness of the natural landscape of the peninsula has been a host of various settlements and has given rise to multiple cultural expressions [24]. Argolid hosts 93 cultural heritage sites and museums, out of which a great majority are archaeological sites [25]. Each and every one of these exhibit site-specific vulnerabilities that require tailored studies catering for their unique characteristics and susceptibilities to extreme events. The Sanctuary of Asklepios (Figure 1 and Figure 2) was a prominent site within the landscape. It was one of the most renowned healing sanctuaries of antiquity, and it was the birthplace of a healing cult devoted to Asklepios. It is located in a valley surrounded by mount Tithnio from the North and mount Kynortio from the East [26].

The vast programs of excavations and protection plans since the second half of the 19th century until today, the national and international critical acclaim of the heritage site, along with the invigorated interest of the Greek government to promote its cultural heritage to the new wave of visitors [27] could have potentially contributed to the nomination of the Sanctuary of Asklepios at Epidaurus to be included in the World Heritage List. It was in 1988 that the archaeological site got with UNESCO in recognising the Sanctuary’s remarkable legacy to the promotion of healing practices and worshipping of healing deities during antiquity (criterion iii) and highlights its contribution to the advancement of medicine to science (criterion vi). Additionally, the ensemble of the buildings’ remains denotes the strength of the believers to the deities’ healing powers; the architecturally extraordinary parts and sculptures are tooted for being model representations of 4^th century B.C. art and architecture and engineering (criteria i, iv), while showcasing its influence on other Asklepieia of the Hellenic and Roman eras (criterion ii).

When referring to the restored monuments, the site exhibits all international standards of reversibility and construction techniques that can be distinguished [28]. The authenticity of the site is also influenced by the current condition of the core and buffer zones. By presidential decree, the core zone bans all new construction [29], whereas the buffer zone is subject to specific restrictions and regulations. The premises of the sanctuary and the natural environment surrounding it provide the necessary coherence to the heritage values. Thus, the core zone of protection was extended in 2012 to provide a bigger area of protection [30].

Parallel to the World Heritage Site nomination, national regulations are put in place to safeguard cultural heritage. In general, all archaeological sites are protected under Law 3028/2002 Article 7, stating that all-immovable monuments dated prior to 1453 are under the ownership of the Hellenic Republic [31]. Therefore, all heritage sites belong to the Ministry of Culture and are managed by the Ephorate of the region in which they belong to. Directions for management come from the competent department of the Ministry of Culture. Consequently, decision-making is centralised and the ministry provides guidance through a top-down scheme to the respective regional offices. The Ephorates are generally charged with planning any and every conservation and restoration work and are generally responsible for the integrity of the site, by acting as decentralised authorities reporting back to the ministry. The scope of their function permeates all aspects of heritage protection [32]. They are not only charged with surveying, excavation, and conservation works but also coordinating actions to raise awareness for the archaeological sites and the cultural values ascribed to them [33].

Past and Present-Day Condition

Past impacts generally manifested as flooding, landslides, soil depositions and subsidence. The literature informs that, despite the central role of water in the function of the rituals, the archaeological site has always experienced considerable issues in managing the flow of water [34]. Located in a valley surrounded by mountains, the sanctuary has long been affected by stagnant water and alluvial deposition. As pinpointed by researchers, these problems must have been more intense during Roman times, when climatological changes, particularly high humidity and intense rainfall, led to the transport and deposition of soil masses from Mount Kynortio towards the sanctuary [21]. By contrast, forest fires and earthquakes appear as relatively rare events for the site, as no historical account of extensive forest fire exists, nor does any trace of large-scale fire damage to the entire sanctuary. Earthquakes, although responsible for substantial damage and even phases of abandonment in antiquity, are not associated in the literature with documented cascading environmental events.

Turning to the present day, the 2014 UNESCO Periodic Report [35] identified that phenomena, such as storms, earthquakes, and wildfires, to be the principal current and potential future threats to the site. The more recent Periodic Reporting Cycle 3 (Section II) [36] refines these findings by providing a more systematic assessment of risk factors and management responses. It confirms that the aforementioned key potential hazards remain and further highlights that temperature fluctuations and local conditions negatively affect the physical fabric of the monuments. At the same time, the report underscores that these impacts are presently limited in spatial extent and largely potential rather than acute and that the sanctuary benefits from a robust legal framework, an effective management system, and a comparatively high capacity to respond. An autonomous fire-protection system, continuous surveillance, fire-safety and evacuation plans that are updated annually, and regular fire-drill exercises are conducted.

Overall, the historical and contemporary evidence converge to indicate that weather and environment-related processes act mainly through the amplification of water-related hazards and the degradation of building materials. Although the most recent periodic report concludes that the Outstanding Universal Values of the site is currently preserved and that management is generally effective, it also implicitly underscores the need for continued and more targeted monitoring to address progressively intensifying climate-related and geophysical risks.

2. Materials and Methods

This research aims to quantify the potential impacts on the values of the archaeological site through the examination of current and future threats and the vulnerability of the materials. It employs a mixed-methods technical approach based on the ABC Method, a systematic risk management framework developed by ICCROM and the Canadian Conservation Institute that helps cultural heritage institutions identify, analyse, and prioritise threats to collections and historic sites using quantified scales for threat frequency (A), value loss (B), and number of items affected (C) [37]. In detail, it enables the risk assessment of threats relevant to cultural heritage by providing a framework for risk identification, the estimation of exposure of assets to specific threats and their vulnerability to them. Since detailed studies examining climate change patterns on site scale is generally scarce [38], this study is based upon the climatic data generated by the Climascape project which are related to the 2065 and 2100 timeframes. Eventually, coupling the abovementioned analyses through a value-based approach, NARA Grids are compiled and impacts on heritage values are assessed which, in turn, feed the ABC Method with relevant data to determine the severity of identified risks. Mindful of the intricate network of specific values that make up the Outstanding Universal Values of the archaeological site, recommendations on adaptation measures are proposed.

While a comprehensive watershed-scale vulnerability assessment would enhance this study, the scope focuses on site-specific hydroclimatic exposure and monument vulnerability given data availability constraints. The methodology deliberately concentrates on the documented exposures and vulnerabilities within the immediate boundaries of the site, recognising, however, that upstream watershed processes represent a critical field for future investigation.

More broadly, the hydroclimatic risks examined here are situated within a wider multi-hazard risk context. Drawing from the excellent condition of the site and its extended buffer zone, as well as the management and monitoring of environmental changes, the role of other threats is captured indirectly through their effects on site.

2.1. Exposure Estimation and Vulnerability Analysis

GIS-based tools prove to be useful in the interpretation of environmental data within a specific geographical area. In this research, ESRI ArcGIS Pro v3.0 is used for the purposes of exposure analysis and visualisation of water-related threats through the Height Above Nearest Drainage (HAND) flood mapping methodology [39]. It is a methodology preferred by government agencies for its ability to generate a “low-complexity, terrain-based approach for inundation mapping using elevation data, discharge–height relationships, and streamflow inputs.” [39]. It enables analysis of water drainage potential within a given area as informed by river discharge potential [40,41].

The selection of this methodology here is two-fold. First, it reveals the water flow pattern in situations where hydrological data are scarce or unavailable. Second, it can generate inundation maps that are not bound to soil properties to reveal the general trend of water flow and of inundation potential. Considering the data scarcity for the region of this study, the application of HAND in this study’s context is not to generate an elaborate quantitative hydrology model based on rainfall data, but rather to visualise how different water accumulation heights could potentially affect the heritage site, indicating possible exposures to flooding and water runoff during an extreme event. The elaboration of these maps, however, should not be confined to the delineated boundaries of the core of the heritage site, but it should also be applied to a macro scale that would reveal the trickle down from Mount Kynortio and the surrounding region.

Overall, the design of this study is constrained by the limited availability of long, continuous hydrometric and rainfall records at the scale of the catchment. In the absence of site-specific data, a fully calibrated rainfall–runoff or hydraulic model would provide a level of quantitative precision that would not be supported by existing data. Therefore, the HAND maps provide a conservative representation of potential inundation patterns that is driven by topography rather than by a specific rainfall event. While this terrain-based approach does not explicitly simulate rainfall intensity and duration or dynamic land cover changes, as it aims to place site-level exposure within the broader hydrological behaviour of the catchment.

It is not in the power or the resources of this paper to generate a comprehensive analysis of the watershed conditions and the vulnerabilities of the catchment, as such analysis require data that could not be retrieved. In recognition of these data limitations, the authors have focused the vulnerability assessment on documented material characteristics and observed degradation patterns at the sanctuary. As such, conclusions rest on evidence that could be reliably substantiated and appropriately calibrated through fieldwork and conservation records.

2.2. Fieldwork

Desk-based research regarding exposures and vulnerabilities is complemented by in situ fieldwork. It aims to assess the integrity and the condition of the site and to analyse current threatening natural phenomena, identify the condition of the heritage assets with regard to their materiality to understand vulnerability. It was scheduled from 7 to 10 February 2023 during the forecasted snowstorms in Peloponnese, to elucidate data before, during, and after an extreme event. Based on the situation encountered, risk statements were generated which were then compared to identified literature to pinpoint climate-related accentuated risks.

2.3. The ABC Method Through a Value-Based Approach

The ABC Method [37] follows five steps in the management of risks: establish the context, identify, analyse, evaluate and treat risks. It is a cycle-based approach that comprises three parameters that are in constant application and review. These are the frequency of occurrence of the extreme event, value loss and area of effect which are scored on a 1–5 scale and, in turn, are multiplied with each other (A × B × C) to generate the magnitude of risk.

The scoring of the parameters is also subject to specific protocols. Value A is fixed as it refers to a predefined timeframe, therefore acquiring a fixed score. Value B refers to the loss of value of each item in the analysis or the extent of damage. It is generally conceived on a comparative scale of “How many affected items would amount for the total loss of one item”. The evaluation of the grading is based on the material vulnerability studies, the current condition of ensembles of artefacts, the comparative analysis of reports highlighting their significance for the site and the expert judgement of the authors of this article. When scoring the C value, the method asks for the grouping of affected assets. The value-based analysis is generally accepted and compatible with the ABC Method [37]. It explains that value subgroups can be the heritage values of each group of the asset.

The Nara Grid is a methodological framework derived from the 1994 Nara Document on Authenticity [42] that operationalizes the concept of authenticity for the systematic evaluation of the authenticity of cultural heritage assets and to assess how change could have adverse effects on these values. Furthermore, it is a structured way to inventory and preserve the both the tangible and intangible qualities of cultural heritage [42]. By utilising the NARA Grids, the cultural heritage values of the site can subsequently be quantified along with the impacts of threats upon them.

3. Results

3.1. HAND Analysis

The flow accumulation map (Figure 3) indicates that the main streams originate from the north-east outskirts of Mount Kynortio and flow towards the southwest, eluding the heritage site. Interestingly, the regional geomorphology also indicates that the flow from the sanctuary is directed towards the west with the inclination to join the main stream located next to it. The drainage and inundation potential illustrated by the HAND map (Figure 4) reveal the advantageous position of the site. Flooding potential of the main stream networks does not seem to affect the site, but could slightly affect the road network leading to the site during an extreme event. The HAND analysis for the wider area of the archaeological site reveals that major streams do not affect the site; however, its proximity to them could possibly introduce smaller, yet significant streams.

Zooming in to the heritage site, a change in tile resolution in the DEM is mandatory. Utilising a 3.90 × 3.90 m tile resolution DEM (the author generated the DEM from the extracted contour lines in ESRI ArcGIS Pro which were provided by the masterplan of the archaeological site. The spatial resolution of the generated DEM corresponds to a spatial resolution of 3.90 × 3.90 m a much higher resolution that the European Digital Elevation Model (EU-DEM), version 1.1), raw data have been calibrated to accommodate certain discrepancies in elevations. Specifically, the DEM has been manually updated to provide with the actual height of the wall ruins that the tile resolution could not record. Due to limited resources, all heights were recorded manually during the fieldwork.

The findings of the flow accumulation map indicate 3 major streams (Figure 5) Stream S1 seems to emerge from the parts behind the upper Koilon of the Theatre and the runoff water from the Theatre itself, where it meets contemporary drainage. The second S2 traverses the area between the Gymnasium and the Temple of Egyptian Gods following the downward inclination next to remains of the post-Roman wall to reach Palaistra, from where it changes direction to find the main stream and is carried outside of the site. Finally, S3 also shows the tendency to traverse the archaeological site, but this flow does not seem to pass through the remains, but instead is mitigated by the restoration works, changing its direction to the north and then letting it flow naturally again outside the site.

The HAND hydrology analysis map (Figure 6) illustrates 3 different water accumulation areas. Overall, an inundation of 0.2 m seems to have the potential to affect the majority of the site during an intense rainfall event. Specifically, affected areas can be found along the previously identified streams and particularly, in the junction of the streams S2 and S3. These two parallel streams seem to generate areas of major accumulation (WA1; WA2). Even though seemingly unrelated, the combination of fieldwork findings and HAND map can afford the assumption that they both could contribute to generation of the westernmost accumulation (WA3). The general trend of the map is in line with the findings of the fieldwork observations.

3.2. Findings of the Fieldwork

Focusing on threat identification, the initial snow cover revealed the parts most susceptible to snow accumulation. These were mainly located above the upper koilon of the Theatre, the Roman Odeion, the racing track of the Stadium, and the open space around the north-eastern part of the site. Even though the artefacts themselves were seemingly not affected, closer inspection revealed the high amount of moisture within the materials, which could potentially lead to damage should freezing occur. When accumulated snow started melting, water reels and areas with water accumulation emerged (Figure 7). Specifically, areas within archaeological remains of monuments—the temple of the Egyptian Gods, the Roman Odeion, and the Roman Baths—with no inclination, exhibited accumulation, whereas in open plains water sipped in the soil. Reels emerged within the site on locations with some degree of inclination following the paths generated by previous events, close to the contours of the artefacts, while others just flowed outside the site.

From runoff to stagnant, water-induced threats introduce cascading threats such as soil depositions, efflorescence, and possible structural deformations [43]. Currently, snowstorm events are not recurring phenomena despite the rare incidence that was witnessed during fieldwork. Even if in situ localization of the manifestations of present hazardous climatic events is paramount in understanding the specificities of the site, more quantitative and higher resolution data are required. Future extreme climatic events cannot be assumed to be confined within the indexes expressed in past and present data. Hydrology analysis, specifically, should be examined on various scales and with the use of various available tools to reveal how flow is established within the heritage site.

The combination of fieldwork findings with hydrology maps enforce the notion of water, as being an important influencing parameter to the site and a potential future threat. Currently, intense rainfall events are common on site and they have the capacity to generate large volumes of water that both flow and inundate certain parts of the archaeological site and some of the regions around the monuments themselves. Thus, it is necessary to return to the literature to explore the estimated climate indexes and the impeding changes for Epidaurus.

3.3. Vulnerability Assessment and Future Impacts

Exposure to water runoff and accumulation has been identified as a potential threat to the archaeological site. Assessing this risk requires analysing the vulnerability of both the natural environment and the site’s monuments. Therefore, these factors should also be examined to better understand the potential future impacts of extreme rainfall events.

Starting with the natural environment of the archaeological site, estimations reveal the high vulnerability of the surroundings to drought, heatwaves, and flooding. In detail, the sanctuary of Asklepios is located in an intense Mesomediterrenean bioclimate with low-quality shallow soils prone to intense dryness and high desertification vulnerability due to their low erosion tolerance and high permeability [44]. Regarding the effects of the expected changes to soil humidity parameters, it is generally accepted that soil erosion processes of drier soil are accelerated by intense rainfall events [45]. Future estimates of the area for the ever-decreasing soil humidity in combination to the intensified rainfall and extreme rainfall events could introduce slacking, deterioration of the soil aggregates and micro-fissurations, accelerating soil erosion and decohesion [22]. In parallel, the anticipated decrease in overall rainfall, combined with rising summer temperatures, could affect vegetation leading to an accumulation of flammable biomass, heightening the risk of soil erosion [20] and the proliferation of parasites within the forest ecosystem [46].

In a change in scale, regarding the materiality of the archaeological artefacts, the identified exposures to water present different vulnerabilities based on the material. The archaeological material is mainly found to be several stone types, brick, and mortar. The study of Varti—Matarangas and Mataragas (2000) informs that the major monuments exhibit 12 stone microfacies in total, of which five make up most of the ones used [18]. The main damaging agents for the foundation stone type have been ice formation within the pores and rainwater [47] with the damaged parts exhibiting disintegration by loss of cohesion and specifically crumbling and by layer exfoliation. They also note that other stone microfacies exhibit lower degrees of damage due to their mineralogical profile and their placement, exhibiting good hardness with slight cracking and splitting along the edges. All in all, the five most used stones present high porosity and irregularities in their microfacies rendering them vulnerable to water damage [18].

3.4. Case Analysis, Value Identification and Risk Statements

The combination of water accumulation exposure maps, the vulnerability of the site and the fieldwork findings pinpoint towards three locations exhibiting higher risk of water damage. Water induced threats will now be explored for the Theatre, the Roman Odeion, and Part of the Site. These case studies are now further examined to fully grasp their values, case-specific vulnerabilities and the extent of exposure to hazards. In turn, the identified values per case are compiled into NARA Grids to reveal which values could be possibly affected by the impacts of risks as indicated by the risk statements.

3.4.1. Theatre

The Theatre of the Sanctuary of Asklepios at Epidaurus embodies cultural values that are foundational to the site’s significance (

Table 1. Negative impacts of water (in light blue) and water and ice (in deep blue) on the values of the Nara Grid of the Theatre.

Theatre	Artistic	Historic	Social	Scientific
Form and Design	The restored and preserved parts of the ancient Theatre are a testimony to the theatrical architecture of the Hellenistic period.	An almost complete picture of its original form because of the excellent preservation of the Koilon and the orchestra. It preserves its original architectural form until the end of its function and was never transformed into a roman one.	The building typology nodes to the past social and artistic use of the space. After all, it was an integral part of the healing process of the sick and a recreational spectacle for other visitors.	It possesses such qualities and state of preservation that splendid example of Theatre architecture.
Materials and Substance	The great selection of stone microfacies during anastylosis ensures visual and aesthetic continuity.	The original drainage pipes of the orchestra are still in use.		Extensive research on materiality of the artefacts can contribute to the thorough understanding of the building and its missing parts.
Use and Function	The Theatre is still notorious for hosting spectacular acts and Theatre plays.	The revival of the original use has boosted exponentially both the integrity and the authenticity of the site.	The Epidaurus festival is organised in the premises of the Theatre and brings together visitors and the local community.
Tradition, techniques and workmanship	Rich decorative elements (stonecaps of the retaining walls and engravings of the Koilon seating) add to the design complexity.	The Theatre is closely related to the history of the development of Greek tragedy or Theatre and to Theatre architecture overall.	It is listed and protected by Diazoma—an NGO that caters for ancient Theatres throughout Greece to promote their interests by attracting sponsors.	“The complex design, planning and construction programme of the Theatre highlight the sophisticated knowledge of the workmen and the architects.
Location and Setting	Carved into the natural rock it feels as if it emerges out of it. The acoustics are of outstanding quality.	The Theatre has always been in the forefront of artistic innovation and is still a sought-after performance stage.	Offers unobstructed view of the sanctuary with the imposing remains visible from parts of it, even though parts of them are not in sight by vegetation.
Spirit and Feeling	The original use keeps the spirit of the place alive.	The visitor attending a performance or just visiting the Theatre can still feel both its archaeological importance and its value as a landmark for artistic innovation.	Groups of visitors occupying the space sometimes have a mini lecture, while being seated at the Koilon, to invoke the qualities of the Theatre.	The combination of superb acoustics and architecture of monumental scale interest researchers who try to decipher the science behind the ethereal experience.

). It is touted as being the most perfect and outstanding examples of theatre architecture of the Hellenistic age [28], boasting exemplary proportions and ideal acoustical properties. The theatre is inseparable from the sanctuary’s archaeological function and signifier of cultural life as it acts both as an archaeological site and as the modern revival of performances through the annual Epidauria festival [17]. Thus, Theatre does not only promote its ancient roots but also becomes the stage for contemporary expression. From a scientifically perspective, it offers rich research value through its well-documented excavation history of the nineteenth century conservation campaigns and scholarly archaeological research [48,49,50].

Regarding the exposure to hazards, water flows around and in the Theatre are effectively managed. Runoff follows the natural contours around the retaining walls, where it disperses and is easily absorbed by the soil, requiring no additional management. However, while the current system effectively controls water flow, shifting climatic conditions could eventually render these measures inadequate. In parallel, intense rainfall can cause water from within the Theatre to trickle down into the orchestra and its surrounding areas. The original drainage pipes remain fully operational, directing water into the restored original channels leading to contemporary underground drainage. While the orchestra’s drainage system is generally sufficient, water spill-off can still occur, resulting in secondary downward flow. Even if the current condition is satisfactory in managing the water flows, the changing climatic indexes could render these works obsolete.

As previously discussed, the combination of soil properties, intensified rainfall, rising temperatures, and prolonged dry periods can lead to severe soil erosion. Water runoff may transport soil downhill, depositing it in lower layers. During extreme events, mud and debris from Mount Kynortio’s foothills could wash into the Theatre, covering its surfaces. Additionally, an increase in dying trees raises the risk of falling trunks damaging the delicate edolia. If extreme snowfall replaces heavy rain, similar risks arise. Ice formation on artefacts, soil, and trees could exacerbate erosion once the snow melts, as observed during fieldwork. Frost could further damage stone artefacts and the surrounding environment, compounding water-related risks. However, regional projections indicate a decline in sub-zero temperatures and snowstorms, with their complete disappearance expected by the century’s end, highlighting the uncertainty of such events (

Table 2. Water-related (RM_W_TH) and frost-related (RM_FR_TH) risk statements to be quantified to derive risk magnitudes for the Theatre.

ID	Description
RM_W_TH	Even though the management of the water masses affecting the Theatre during intense rainfall is adequate, the changing climatic conditions can affect its efficacy in the future, leading to more risks.
RM_FR_TH	A snowstorm event, even though decreasing, could lead to the generation of ice particles within the pores and the micro cracks of the weakened material and lead to major cracking.

).

3.4.2. Roman Odeion

The Roman Odeion a culturally rich and typologically distinct monument (

Table 3. Negative impacts of water (in light blue), ice (in grey) and water and ice (in deep blue) on the values of the Nara Grid of the Roman Odeion.

Roman Odeion	Artistic	Historic	Social	Scientific
Form and Design	It is an example of a divergent Roman Odeion. The orchestra is situated lower than the side entrances featuring a floor mosaic. The access to the auditorium was made possible via the use of three staircases.	The Odeion is situated on the northern part of the complex’s courtyard incorporating its walls the columns of the interior colonnade as well as other architectural elements of the former building.		The Odeon should be dated in the end of the 2nd or early 3rd century AD. Several construction phases can be distinguished on the building, which can provide valuable insight for the comparative dating of on-site structures.
Materials and Substance	The walls are made up of semi processed stones, bricks in opus mixtum and reused building stones from the original building. The bonding agent used throughout the structure are several types of mortars.	The structure typology of the Odeion during the Roman times lends itself to the need of a fast and economic construction. The interiors in raw brick and the few embellishments could also attest to this.		The analysis and cataloguing of the structural material are useful practices in tracing original material in other parts of the sanctuary.
Use and Function				A comprehensive conservation and restoration plan could highlight its great reuse potential.
Tradition, Techniques, and workmanship	Example of the craftsmens’ mastery to build upon remains and selecting proper existing material to be reused to ensure structural homogeneity. Deviations to the form of the Odeion could be attributed to this -among other factors.	This building was erect to house “mystical drama” rituals which were previously held in the open space within the Gymnasium.	Tradition, techniques and workmanship	Exemplary typology deviating from the Roman Odeia of the 2nd c. A.D.
Location and Setting	The remains of the Odeion are an indispensable part of the palimpsest of the Gymnasium building and the Sanctuary itself.	These roman remains inform considerable parts of the historic interpretation of the sanctuary and the overall comparative study of Roman monuments.		Set in this intricate archaeological site, it could assist in the interpretation of findings of ongoing research.
Spirit and Feeling	The original form of the building can still be distinguished easily by the visitor.	The preserved remains can still inspire a mental reconstruction of how a concert could have been experienced.	Visitors are drawn by the imposing complex of Gymnasium and they try to obtain a glimpse of the Koilon of the Odeion.

). It is in line with the Roman practice of repurposing and retrofitting existing structures to fit contemporary needs. In this case, a roofed Odeion was inscribed within the footprint of an earlier gymnasium [28], preserving a plan comprising stage, semi-circular orchestra, cavea, and service spaces. Generally, it belongs to the typology of roofed Odeia with an emphasis of simple, yet effective design, devoid of extravagant features [51]. Its materiality and construction technology are illustrative of Roman construction [18,51], thus serving as a comparative case for wider studies of Roman architecture within the region. The Roman Odeion had witnessed diverse social functions with rich performative elements with the most notable uses being hymn concerts and performances complementary to ritual meals [52]. Its excavation and intermittent restoration history [53] makes the Odeion a key node for understanding the palimpsest of the historic phases of the archaeological site.

The Roman Odeion faces major issues with water stagnation which is exacerbated by its current state—as an interior space it was not meant for exposure to the elements. Fieldwork confirms that stagnant water, combined with climate variables, accelerates damage. The extent of deterioration remains uncertain due to dense vegetation covering the cavea and orchestra. However, evidence suggests plant roots may be damaging the underlying material. Aware of the future climate projections, increased rainfall could lead to greater water stagnation, saturating the Odeion’s structural integrity and materiality (

Table 4. Water-related (RM_W_RO) and frost-related (RM_FR_RO) risk statements to be quantified to derive risk magnitudes for the Roman Odeion.

ID	Description
RM_W_RO	The remains of the interior of the Roman Odeion that used to be sheltered from rain are now exposed. Stagnant water is, thus, accumulated and could lead to further material deterioration and loss of value.
RM_FR_RO	The already severely damaged archaeological remains are vulnerable to ice formation, which could further deteriorate the already compromised material.

).

3.4.3. Part of the Archaeological Site

The selected part of the sanctuary is central to the site’s identity by enclosing the Temples of Asklepios and Artemis, the Tholos, the Enkoimeterion/Avaton. These monuments are grouped together as they constitute the core of ritualistic and therapeutic character of the sanctuary [54]. Architecturally, this part of the site demonstrates the evolution from the Hellenistic to the Roman and post-Christian phases of the site, thus attesting to its the multi-layered history [28]. Specifically, this grouping emerged from their significance not only as per their individual values and characteristics, but rather from their juxtaposition and interdependence within this cultural context. Through this grouping, the ensemble testifies to the history of healing and medicinal practices, spanning from prehistory up to the institutionalisation of the medical practice [54]. In parallel, this group was also formed because it exhibits the engineering capacities that enabled its healing practices, as it still preserves evidence of the hydraulic system catering to water supply and sewage of the sanctuary (

Table 5. Negative impacts of water (in light blue) and water and ice (in deep blue) on the values of the Nara Grid of a part of the Archaeological Site.

Site	Artistic	Historic	Social	Scientific
Form and Design	One of the most perfect examples of healing sanctuaries of antiquity exhibiting integrity of the inscribed values, authenticity and sane restoration works.	Exhibits all the various consecutive phases and latter transformations to accommodate the needs of each consecutive era.	Research conducted on key monuments has been published, providing didactic content all types of publics—from laypeople to fellow researchers.	The layout and the remains within the site provide insight in various temporal and spatial scales.
Materials and Substance		The site has witnessed various conservation and restoration works which add to the multilayered reading of the site.		The site is rich in artefacts that are yet to be excavated.
Use and Function		The remains of the buildings still retain the basic spatial planning principles of the latest phase of the sanctuary.	The sanctuary’s addition to the MOREA network proves the potential of the sanctuary to influence cultural routes and to promote the interests of the surrounding communities.
Tradition, techniques and workmanship	Exemplary restoration works complement the existing remains and ensure their longevity.	The most renowned healing sanctuary of the whole Hellenic and Roman world.		Healing practices resembling modern medicine were applied there. Many deem this place to be the foundation of western medicine.
Location and Setting	According to Hippocrates, the site exhibits the qualities that a sanctuary should possess pure water rising from springs and a rich landscape.	Anastylosis restored the third dimension and established the height necessary for the proper understanding of the site.	The strategic position of the sanctuary in the Argolid Peninsula, the revival and enhancement of the archaeological site provide business opportunities to the local community.	The key position of the Sanctuary of Asklepios could inform new research relevant to the development of the surrounding region and NE Peloponnese.
Spirit and Feeling	The artefacts’ positions within the site and the richness of the landscape enhance the narrative of the sanctuary as a place of healing.	The site was devoted to Gods with healing properties since prehistory. Specific remains still attest to this.	Visitors are still intrigued by the expansiveness of the site. The various routes within the sanctuary invite the visitors to wander around and explore.	There is the initiative of enhancing the site to gradually become an archaeological park in the long-term. Few of the incentives are the restoration of key monuments and the reinstitution of the proper entrance to the sanctuary—as it was during its heyday.

) [55].

The Part of the Site indicates a dynamic water flow pattern, transitioning between free flow and accumulation. Water originating from the open plains west of the Avaton building moves around the Temple of Asklepios, briefly accumulating over the remains of the post-Roman wall before continuing along it. Another accumulation point forms over the Palaestra remains before the flow exits the archaeological site through a small natural channel. These flows could impact the surrounding landscape, the supplementary outdoor artefact conservation area and the adjacent workshop building due to the formation of a deep reel in this section. Water accumulation at the sanctuary’s lowest point also affects archaeological remains as area’s topography, does not facilitate its natural drainage (

Table 6. Water-related (RM_W_SI) and frost-related (RM_FR_SI) risk statements to be quantified to derive risk magnitudes for part of the Site.

ID	Description
RM_W_SI	Water reels and channels are formed during intense rainfall originating from NE of the site and accumulating to the W. The constant change between flow and accumulation can lead to mass deposition, accelerate erosion processes and affect buried artefacts on the western part. As a result, major potential for systematic research will be lost.
RM_FR_SI	The compromised archaeological remains scattered in the western part of the site already exhibit heavy damage and they are at the point of losing value. Future frost damage can lead to complete loss of value.

).

3.5. Towards a Risk Assessment—The ABC Method

The detailed elaboration on the exposures, vulnerabilities, and present and potential future impacts have informed the basis of the risk assessment of these cases.

These three cases have revealed specific risk scenarios affecting both their materiality and their values in very different ways. The classification of these risks is now explored utilising the ABC Method for the generation of risk magnitudes to reveal priority areas for the application of disaster risk reduction measures.

Evaluation of ABC Parameters

Scoring of the A, B, and C parameters closely follows the method explained by Michalski and Pedersoli (2016) [37] and in Section 2.3.

The first step in the analysis requires that the asset undergoes grouping, in the form of a value table (

Table 7. Value table of the asset and its groups—estimation of subgroup percentages.

Group	Group as % of Asset	Value subgroup (NARA Dimensions)	Number of Items in Value Subgroup	Subgroup as % of Group (NARA Aspects Out of 6)	Subgroup as % of Asset	Item as % of Asset
Theatre	30	TH—Artistic	6	28.58	8.574	1.429
Theatre	30	TH—Historic	6	28.58	8.574	1.429
Theatre	30	TH—Social	5	23.8	7.14	1.428
Theatre	30	TH—Scientific	4	19.04	5.712	1.428
Roman Odeion	20	RO—Artistic	5	31.25	6.25	1.25
Roman Odeion	20	RO—Historic	5	31.25	6.25	1.25
Roman Odeion	20	RO—Social	1	6.25	1.25	1.25
Roman Odeion	20	RO—Scientific	5	31.25	6.25	1.25
Site	50	SI—Artistic	4	21.05	10.52	2.63
Site	50	SI—Historic	6	31.57	15.785	2.63
Site	50	SI—Social	4	21.06	10.52	2.63
Site	50	SI—Scientific	5	26.32	13.16	2.63

), so that the estimation of C and B values are possible.

In this case the asset (the Archaeological Site of the Sanctuary of Asklepios) is divided into groups of the percentages of the groups of assets. The case studies previously analysed comprise the asset and their group as percentage of the asset is calculated mainly based on their spatial expansion. Adopting a value-based approach, the groups are subdivided into NARA dimensions value subgroups, with each one of them corresponding to the number of values expressed in the NARA grid.

The Subgroup as % of group (NARA Aspects out of 6) is thus expressed in the following formula:

$$\mathrm{S}\mathrm{u}\mathrm{b}\mathrm{g}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p}\% \mathrm{o}\mathrm{f} \mathrm{g}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p}={\displaystyle \frac{\mathrm{v}}{\sum \mathrm{v}}}\times 100$$

where

$\mathit{v}$ is the number of items in value subgroup

$\sum \mathit{v}$ is the sum of the number of items in value subgroup for all value subgroups of a single group.

In turn

$$\mathrm{S}\mathrm{u}\mathrm{b}\mathrm{g}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p}\% \mathrm{o}\mathrm{f} \mathrm{a}\mathrm{s}\mathrm{s}\mathrm{e}\mathrm{t}=\mathrm{S}\mathrm{u}\mathrm{b}\mathrm{g}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p}\% \mathrm{o}\mathrm{f} \mathrm{g}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p}\times \mathrm{G}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p} \mathrm{a}\mathrm{s} \% \mathrm{o}\mathrm{f} \mathrm{a}\mathrm{s}\mathrm{s}\mathrm{e}\mathrm{t}$$

Finally, the “Item as % of asset” is expressed as

$$\mathrm{I}\mathrm{t}\mathrm{e}\mathrm{m} \mathrm{a}\mathrm{s} \% \mathrm{o}\mathrm{f} \mathrm{a}\mathrm{s}\mathrm{s}\mathrm{e}\mathrm{t}={\displaystyle \frac{\mathrm{S}\mathrm{u}\mathrm{b}\mathrm{g}\mathrm{r}\mathrm{o}\mathrm{u}\mathrm{p} \mathrm{a}\mathrm{s} \% \mathrm{o}\mathrm{f} \mathrm{a}\mathrm{s}\mathrm{s}\mathrm{e}\mathrm{t}}{\mathrm{n}}}\times 100$$

where n is the number of items in value subgroup

The first step to derive the C-score for each affected items per damage mode (

Table 8. Estimation of C-value of affected items from water modes.

Affected Items Water Modes	Item as % of Asset	Number of Items Affected by This Risk	Fraction of Asset Value Affected	C Score on ½-Step Scale
TH—Artistic	1.429	3	4.287	3½
TH—Historic	1.429	1	1.429	3
TH—Social	1.428	2	2.858	3½
TH—Scientific	1.428	2	2.858	3½
		ΣTH:	11.432	4
RO—Artistic	1.25	3	3.75	3½
RO—Historic	1.25	2	2.5	3½
RO—Social	1.25	_	_	_
RO—Scientific	1.25	3	3.75	3½
		ΣRO:	10	4
SI—Artistic	2.63	2	5.26	3½
SI—Historic	2.63	3	7.89	4
SI—Social	2.63	1	2.63	3½
SI—Scientific	2.63	2	5.26	3½
		ΣSI:	21.04	4½

and

Table 9. Estimation of C-value of affected items from ice.

Affected Items Ice	Item as % of Asset	Number of Items Affected by This Risk	Fraction of Asset Value Affected	C score on ½-Step Scale
TH—Artistic	1.429	1	1.429	3½
TH—Historic	1.429	_	_	3
TH—Social	1.428	1	1.429	3½
TH—Scientific	1.428	_	_	3½
		ΣTH:	2.858	3
RO—Artistic	1.25	2	2.5	3½
RO—Historic	1.25	2	2.5	3½
RO—Social	1.25	_	_	_
RO—Scientific	1.25	1	1.25	3½
		ΣRO:	6.25	4
SI—Artistic	2.63	1	2.63	3½
SI—Historic	2.63	1	2.63	4
SI—Social	2.63	_	_	3½
SI—Scientific	2.63	_	_	3½
		ΣSI:	5.26	3½

) is the estimation of the “Fraction of asset value affected”, and it is expressed by

$$\mathrm{F}\mathrm{r}\mathrm{a}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{o}\mathrm{f} \mathrm{a}\mathrm{s}\mathrm{s}\mathrm{e}\mathrm{t} \mathrm{v}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e} \mathrm{a}\mathrm{f}\mathrm{f}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{e}\mathrm{d}=\mathrm{I}\mathrm{t}\mathrm{e}\mathrm{m} \mathrm{a}\mathrm{s} \% \mathrm{o}\mathrm{f} \mathrm{a}\mathrm{s}\mathrm{s}\mathrm{e}\mathrm{t}\times \mathrm{N}\mathrm{u}\mathrm{m}\mathrm{b}\mathrm{e}\mathrm{r} \mathrm{o}\mathrm{f} \mathrm{i}\mathrm{t}\mathrm{e}\mathrm{m}\mathrm{s} \mathrm{a}\mathrm{f}\mathrm{f}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{e}\mathrm{d} \mathrm{w}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}/\mathrm{i}\mathrm{c}\mathrm{e}$$

After the scoring of C-values, the scoring of B-values of the framework follows the one expressed by the Michalski and Pedersoli (2016) [37]. The B-values is estimated by damage mode for the two timeframes (

Table 10. Estimation of B-value for 2065—Water Damage.

Water Damage	Score	Number of Damaged Items Equivalent to One Total Loss
Theatre	2	~500
Roman Odeion	3½	~30
Site	4	~8

,

Table 11. Estimation of B-value for 2065—Frost Damage.

Frost Damage	Score	Number of Damaged Items Equivalent to One Total Loss
Theatre	2½	~300
Roman Odeion	4½	~7
Site	4	~10

,

Table 12. Estimation of B-value for 2100—Water Damage.

Water Damage	Score	Number of Damaged Items Equivalent to One Total Loss
Theatre	2½	~200
Roman Odeion	4	~10
Site	4½	~5

and

Table 13. Estimation of B-value for 2100—Frost Damage.

Frost Damage	Score	Number of Damaged Items Equivalent to One Total Loss
Theatre	2	~400
Roman Odeion	3	~50
Site	3½	~25

).

Similarly, the A-values for the timeframes 2065 and 2100 are scored 3 and 3½ accordingly.

The analysis of the A, B, and C parameters have assisted in assigning various values indicative of each case study and their parameters. Risk magnitude is the generation of a single value which can quantify the overall risk and enable a comparison among them to prioritise action.

The evaluation of the results for the 2065 timeframe shows clear differences in how the three monuments respond to existing risks (

Table 14. Risk magnitudes per Risk type for the 2065 timeframe.

Risk Types for the 2065 Timeframe	Risk Magnitudes
Risks related to water damage	RM_W_TH = A × B × C = 3 × 2 × 4 = 24
	RM_W_RO = A × B × C = 3 × 3½ × 4 = 42
	RM_W_SI = A × B × C = 3 × 4 × 4½ = 54
Risks related to frost damage	RM_FR_TH = A × B × C = 3 × 2½ × 3 = 22.5
	RM_FR_RO = A × B × C = 3 × 4½ × 4 = 54
	RM_FR_SI = A × B × C = 3 × 4 × 3½ = 42

). The central part of the sanctuary already appears as the most vulnerable area, mainly because of its large extent and the concentration of valuable monuments within it. The Roman Odeion follows exhibiting sensitivities to both water accumulation and to temperature-related fluctuations resulting in frost. The Theatre remains more stable overall; however, it still shows measurable risk exposures to identified threats, though at a lower level than the other two. The 2065 data suggest that the site’s wider landscape features and the monuments’ material conditions together define a hierarchy of vulnerability. Spatially extensive areas that include artefacts of compromised materiality, such as the central sector and the Odeion, require more immediate attention than the Theatre.

By 2100, all three cases show increasing exposures but at different rates (

Table 15. Risk magnitudes per Risk type for the 2100 timeframe.

Risk Types for the 2100 Timeframe	Risk Magnitudes
Risks related to water damage	RM_W_TH = A × B × C = 3½ × 2½ × 4 = 35
	RM_W_RO = A × B × C = 3½ × 4 × 4 = 56
	RM_W_SI = A × B × C = 3½ × 4½ × 4½ = 70.875
Risks related to frost damage	RM_FR_TH = A × B × C = 3½ × 2 × 3 = 21
	RM_FR_RO = A × B × C = 3½ × 3 × 4 = 42
	RM_FR_SI = A × B × C = 3½ × 3½ × 3½ = 42.875

). The Theatre demonstrates the largest proportional rise in water-related risk at about a 45% increase, suggesting that although its overall vulnerability is still lower, its condition could worsen faster than expected if left unmonitored. The Roman Odeion also records a significant growth of around 30% in water-related risk, confirming that moisture-related risks will still be present in the future. Its frost-related sensitivity gradually decreases by about one-fifth for this timeframe. The central part of the archaeological site retains the highest overall exposure, but its relative growth between timescales is slightly smaller. This finding does not support the idea that the risk stabilises in the future, but rather that the risk scales reach their overall highest scales with regard to the ABC dimensions. This means that risks will remain constantly high and reveal the need of a more targeted risk assessment study to specific assets.

The parallel analysis of the findings of both timeframes reveals a pattern that highlights complementary priorities spanning these two timeframes for the protection of the most exposed artefacts. In the short term, immediate measures should focus on the central part of the archaeological site and the Roman Odeion as they both combine high exposures to risk with significant material sensitivity. In the longer term, attention should gradually extend to the Theatre, whose proportional increase warns of future possible impacts if preventive action is delayed. Overall, the comparison between the 2065 and 2100 timeframes suggest that water-related risks will be the main the ones that will need to be managed, while in contrary, frost-related ones are expected to gradually decrease over time.

This analysis calls for a conservation strategy that would address the issues based on strategic priorities. Therefore, gradual interventions should be planned where exposures of both artefacts and associated values are already severe. Continuous monitoring options should be explored where the trend suggests future emerging risks.

4. Discussion

The risk assessment of the previous part has been a critical step towards understanding how water constitutes a damaging agent to the values of the heritage site. So far, research supports that both the Sanctuary of Asklepios at Epidaurus and the surrounding natural environment could be susceptible to the impacts of the intensified rainfall events.

Moving forward from understanding risk and the subsequent impacts of inaction, it is suggested that adaptation actions for the archaeological site of the Sanctuary of Asklepios at Epidaurus should become a strategic priority. This study examines site-level hydroclimatic exposure and vulnerability, but a more comprehensive understanding would be beneficial. In detail, a catchment-scale vegetation and soil degradation assessment upstream of Mount Kynortio would benefit the archaeological site as soil and mass deposition potentials would be revealed. Regarding the characteristics of rainfalls, intensity-duration-frequency curves [56] account for rainfall characteristics, constituting critical components for upstream climate change adaptation strategies. As such, future work integrating watershed-scale vulnerability alongside site-level risk assessments would strengthen adaptive planning of both the archaeological site and the catchment area.

UNISDR defines resilience as “… the ability of a system, community or society exposed to hazards to resist, absorb, accommodate to and recover from the effects of a hazard in a timely and efficient manner, including through the preservation and restoration of its essential basic structures and functions.” [57]. To build resilience, the risks illustrated should be subject to disaster risk reduction (DRR) practices to these uncharted conditions, through climate change adaptation (CCA) practices. CCA refers to all those necessary region-specific modifications on human and natural systems to be able to better respond to the influence of the changing climate [58].

Striving for a holistic approach to CCA, adaptation measures should also be mindful of the specific threats and vulnerabilities of the monuments located within the archaeological site to minimise the impacts of the interventions. Regarding the Theatre, focus should be given to the establishment of preventive measures that are climate change-aware and mindful of the Theatre’s high value. Given its well-conserved state and medium vulnerability, damage may not occur during this study’s selected timelines. Therefore, an extensive monitoring system is recommended to track potential impacts from intensified rainfall events. Additionally, elaborate hydrology studies should analyse water flow patterns from Kynortio Mount to the Theatre and its drainage network, so as to lower any uncertainty during hydrological modelling. This approach supports the “no project” option while ensuring informed decision-making for future preservation efforts.

For the Roman Odeion, a procedural approach is needed due to significant deterioration from excavation and lack of conservation. Initial pilot unearthing of archaeological remains and technical evaluations will guide preservation strategies, combining preventive and remedial measures. If the remains are stable, restoration could revive its original function, requiring drainage studies and possible roofing. However, high costs may render restoration unfeasible. If funding is unavailable or the remains are too fragile, preventive conservation through re-excavation and a baseline plan would be necessary, though only as a step toward eventual sheltering. A low-cost alternative includes integrating extreme rainfall management into emergency plans, with a mechanical drainage pump and monitoring technologies for better site protection.

Regarding the part of the Site, action should aim towards the segmentation of the northwestern water flow into three smaller, more manageable streams by establishing separate drainage systems for WA1-3 (Figure 6). Adjusting inclinations around accumulation areas W1 and W2 is crucial, as their current elevations may differ from the original archaeological levels due to past excavations. Targeted groundworks should direct water westward to the new drainage system, reducing stagnation in WA3.

In addition to on-site drainage improvements and preventive conservation, effective long-term adaptation should also consider measures in the upstream catchment. These include maintaining and enhancing forest and shrub cover on the slopes of Mount Kynortio, promoting soil and erosion control practices that stabilise shallow, erosion prone soils and ensuring regular maintenance of the interception gutter and related drainage infrastructure that currently divert runoff from the upper slopes around the Theatre. Coordinated management of both the sanctuary and its contributing catchment is therefore essential to reduce cascading hydroclimatic impacts under future climate scenarios.

Delving even deeper, rethinking the efficacy of the national centralised management of the archaeological sites to accommodate the follow-up monitoring and any emergency response actions during an extreme event would be beneficial. A management plan tailored to the site could potentially enforce and operationalise the monitoring scheme in regular intervals by also implementing DRM cycles.

Considering CCA as a systems-wide process, action to mitigate damage should not be confined within the margins of the core and the buffer zone. Striving to achieve the Sustainable Development Goals, respecting the Sendai Framework and being mindful of the Paris Agreement, CCA efforts of the Sanctuary of Asklepios at Epidaurus should also prioritise the inclusion of the relevant communities. Mitigation of value loss is not only a matter of archaeological site protection from the impacts of climate change but also a matter of providing with the means to promote sustainable CCA solutions to other affected sectors to ensure resilient ecosystems that drive sustainable development.