Emerging flood risks for dams: addressing climate change and advancing engineering solutions

Overview

The BDS Annual General Meeting (AGM) will start at 18:00, followed by the lecture.

Floods are the leading external threat to dam safety worldwide. In recent decades, extreme rainfall has caused overtopping incidents, near-failures, and catastrophic breaches, including the 2023 Derna failures in Libya and the 2024 Arbaat Dam collapse in Sudan.

Glacial lake outburst floods (GLOFs) further highlight the growing risk, showing how climate change is altering flood magnitude and timing beyond traditional design assumptions. Poor dam management increases vulnerability to these events.

Evidence shows climate change is intensifying extreme rainfall and floods while increasing uncertainty in hydrological predictions. Shifts in atmospheric circulation, glacier retreat, and changing snowmelt are creating more unpredictable hydrological regimes.

As a result, relying solely on historical data underestimates future extremes, making climate considerations essential in dam design.

Globally, flood magnitudes and river flows are rising and will likely continue increasing this century. Many existing spillways may lack capacity for future floods, raising safety concerns.

Common issues in recent failures include inflow exceedance, poor operation and maintenance, overtopping, and underestimation of hydrological risk. Under-designed or poorly maintained dams face the highest risks.

For many dams—especially medium-sized ones—original design flood estimates are now outdated. Small and medium embankment dams are particularly vulnerable, requiring strategic upgrades to spillway capacity and overtopping resilience.

Cemented Material Dams (CMDs), which combine embankment and concrete/RCC features, offer improved overtopping resistance for both new and existing dams. Concrete, RCC, and CMD dams have shown strong resilience, as demonstrated by Bhutan’s Tala dam in 2025.

Where foundations are erosion-resistant, controlled overtopping may be feasible, while embankment dams can be strengthened with RCC or CMD downstream protection to withstand extreme events.