Nearly Three-Quarters of World Heritage Sites Are at High Risk from Water-Related Hazards

A new analysis by UNESCO and World Resources Institute (WRI) reveals that 73% of World Heritage sites are highly exposed to water-related hazards, such as drought, water stress, or riverine and coastal flooding. Strengthening water stewardship is essential to protect these sites and the communities and ecosystems they sustain.

A Precious Resource Under Growing Threat

Water-related hazards—including floods, droughts, and storms—have accounted for over 90% of the world’s major disasters since 1970, resulting in more than 2 million deaths and economic losses exceeding USD 3.6 trillion, according to the World Meteorological Organization (WMO). World Heritage sites have not been exempted from these hazards and face increasing threats to their natural and cultural values. These sites stand as powerful reminders of humanity’s enduring relationship with water. From awe-inspiring landscapes shaped over millennia to cultural landmarks forged through human ingenuity—such as ancient irrigation systems, historic canals, and modern engineering achievements—they reflect the cooperation with nature that has enabled societies to flourish across generations. Yet, while water is fundamental to their significance, it can also pose serious risks when its balance is disrupted, threatening the integrity of these irreplaceable places.

A new analysis by UNESCO and World Resources Institute (WRI) highlights the scale of these threats: 73% of World Heritage sites are highly exposed to at least one water-related hazard—such as drought, water stress, or riverine and coastal flooding—and 21% face multiple overlapping risks. Around the world, World Heritage sites are increasingly caught between the extremes of too much and too little water, with climate change, urbanization, river regulation, and upstream water withdrawals intensifying these pressures, especially in regions such as the Middle East, North Africa, parts of South Asia, and northern China.

“The Aqueduct Water Risk Atlas gives us critical data to track how water risks are evolving around the world. These insights are more urgent than ever, helping governments, site managers, and communities take targeted action — before floods, droughts, or water shortages cause irreversible damage to treasured places that serve as lifelines for both people and ecosystems,”

Samantha Kuzma, Aqueduct Data Lead at World Resources Institute.

Approximately 600 World Heritage sites are highly exposed to water scarcity conditions — reflected in water stress or drought— making it the most widespread water-related risk, threatening nearly half of all properties. The vast majority (around 90%) of these exposed sites are cultural properties . While natural sites face a comparatively lower level of exposure, they are increasingly experiencing conditions that place growing stress on ecosystems and biodiversity. Sites such as the Ahwar of Southern Iraq and Mosi-oa-Tunya / Victoria Falls (Zambia / Zimbabwe) have endured severe multi-year droughts since 2020. Drought also heightens the risk of wildfires, compounding the damage: in the Pantanal Conservation Area (Brazil) and Noel Kempff Mercado National Park (Bolivia), prolonged dry conditions have fueled intense fires with severe impacts on flora, fauna, and local communities.

Drought at Mosi-oa-Tunya / Victoria Falls (Zambia / Zimbabwe) in 2019 / Source: Copernicus Browser

Severe flood risk, both riverine and coastal, affects approximately 400 World Heritage sites. Floods have already impacted both natural and cultural World Heritage properties, highlighting the urgent need for strengthened resilience. In 2020, Rwenzori Mountains National Park (Uganda) experienced significant climate-related flooding that that disrupted river systems, posing challenges for both local communities and wildlife. In 2022, major flooding led to the temporary closure of Yellowstone National Park (United States of America), with over $20 million required for infrastructure repairs before the park could reopen. More recently, in 2024, severe flooding in Kaziranga National Park (India) resulted in the loss of more than 200 animals, including 10 endangered rhinos, while Sagarmatha National Park (Nepal) has been affected by Glacial Lake Outburst Floods (GLOFs) linked to accelerating glacial retreat.

© ICIMOD

Cultural sites have also experienced serious impacts from flooding. The catastrophic floods that left nearly one-third of Pakistan submerged in 2022 caused significant damage to the Archaeological Ruins at Moenjodaro. Other ancient sites such as the Minaret and Archaeological Remains of Jam (Afghanistan), Angkor (Cambodia) and Petra (Jordan), have also been affected by flooding, with damage to their integrity. In parts of Africa, communities in Timbuktu (Mali) and the Historic Centre of Agadez (Niger) are facing the compounded challenges of severe drought followed by intense flooding — a clear illustration of increasing climate variability.

Flood at Archaeological Ruins at Moenjodaro (Pakistan) in 2022 / Source: Copernicus Browser

Around 50 World Heritage sites are highly exposed to coastal flooding. Some cultural sites are already experiencing the impacts, with growing risks to their integrity. The Complex of Hué Monuments (Viet Nam) has endured repeated flooding in recent years, accelerating deterioration. The Forts and Castles along the coast of Ghana, face increasing danger from shoreline erosion and rising seas, putting at risk these important remains of fortified trading posts that formed part of early global trade history. While coastal flooding has not yet caused major reported damage at natural World Heritage sites, the risk is rising. Sites such as the Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China and Banc d’Arguin National Park (Mauritania) are highly vulnerable, as sea level rise could transform or submerge critical coastal habitats essential for migratory species.

"This analysis underscores the urgent need to address water-related risks to World Heritage sites, which are being intensified by climate change. Strengthening resilience through innovation, traditional knowledge, and cooperation is essential to safeguarding these irreplaceable places for future generations."

Lazare Eloundou Assomo, Director of World Heritage

Towards Solutions: Protecting Heritage Through Water Stewardship

Despite these challenges, examples of effective action demonstrate that solutions are possible—particularly when supported by international cooperation, innovation, and traditional knowledge. UNESCO actively supports States Parties in addressing water-related threats through a combination of emergency mechanisms, technical guidance, and long-term cooperation. Emergency support is provided through instruments such as the World Heritage Fund’s International Assistance, the Rapid Response Facility (RRF) and the Heritage Emergency Fund (HEF), while expert missions under the World Heritage Convention’s Reactive Monitoring process help guide response efforts. UNESCO also provides capacity building and technical support to strengthen local responses, contributing to long-term resilience, disaster risk reduction, and sustainable water management at World Heritage sites through programmes such as the Intergovernmental Hydrological Programme (IHP).

Integrated water resource management (IWRM) — which promotes the coordinated development and management of water, land, and related resources — is increasingly being incorporated into conservation strategies for World Heritage properties. At Petra (Jordan) and the Old City of Sana’a (Yemen), for example, IWRM principles are guiding flood risk reduction strategies such as early warning systems, which help safeguard monuments from increasingly severe flash floods. Similarly, in the Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China, a government ban on land reclamation, followed by wetland restoration efforts, has led to a fivefold increase in bird populations in some areas, providing renewed habitat for migratory species.

© UNESCO / Community Engagement through Risk Prevention in Petra

Heritage-sensitive climate adaptation is also key. The Chan Chan Archaeological Zone (Peru) illustrates how site managers are applying innovative water management measures — including drainage improvements and protective earthworks — to reduce the impact of increasingly intense rainfall and flooding on fragile adobe structures. At the Minaret and Archaeological Remains of Jam (Afghanistan), UNESCO has supported emergency measures to stabilize the structure following flood events that endangered its integrity, along with technical assistance for improved flood management in the surrounding valley.

© UNESCO / The Minaret and Archaeological Remains of Jam, a UNESCO project to safeguard the iconic site

Transboundary cooperation plays a vital role where shared water systems support World Heritage values. The Permanent Okavango River Basin Water Commission (OKACOM), through collaboration between Angola, Namibia, and Botswana, coordinates efforts to protect the seasonal flooding that sustains the Okavango Delta’s biodiversity and local livelihoods. Similarly, at Iguaçu National Park, on the border between Brazil and Argentina, park managers work with upstream stakeholders to maintain sustainable water flows that protect the falls’ ecosystem while supporting vital hydroelectric production at the Itaipu Dam. To address the consequences of melting glaciers and increased occurrences of Glacier Lake Outburst Floods (GLOFs) due to climate change impacts, UNESCO is engaging with communities in the Sagarmatha National Park (Nepal) to identify potential adaptation pathways using the Climate Risk Informed Decision Analysis (CRIDA).

Traditional knowledge, community stewardship, and partnerships between local communities, national authorities, and international organizations are central to many successful initiatives. In the Rice Terraces of the Philippine Cordilleras, the revitalization of ancient irrigation systems and forest restoration supports both cultural heritage and resilience to drought and erosion. In the Ahwar of Southern Iraq, joint efforts have facilitated the restoration of marshlands, enhancing water governance and helping buffer against drought and salinity.

Modern technology further complements these approaches. Tools such as GIS mapping, remote sensing, and water quality monitoring provide real-time data to inform decision-making and enable site managers and authorities to respond effectively to emerging threats. To support this, UNESCO’s World Heritage Online Map Platform (WHOMP), serves as an important resource for monitoring water-related risks and informing site-level planning.

These efforts and solutions are among the many actions contributing to the protection of World Heritage sites and the strengthening of their resilience for generations to come. World Heritage sites are not static relics of the past, but dynamic systems shaped by human ingenuity, natural forces, and the enduring relationship between people and water. Strengthening their protection calls for an integrated approach that combines time-honoured practices with scientific innovation, draws on both traditional knowledge and modern science, and fosters inclusive governance and transboundary cooperation. Advancing water stewardship that supports both cultural and natural heritage is essential to safeguarding their Outstanding Universal Value and ensuring their continued contribution to sustainable development and the well-being of communities worldwide.

UNESCO gratefully acknowledges the support of the Government of Flanders (Belgium) for the World Heritage Online Map Platform (WHOMP), which made this analysis possible.