Impact of Geoengineering in Offsetting Climate Change-Induced Dam Break Risk

Dam safety is a primary concern for countries worldwide, as dam failure can have catastrophic consequences, including fatalities and losses to the economy, ecology, and environment. In recent decades, there has been growth in consensus that climate change has enhanced the risk to dams due to floods triggered by more frequent and intense extreme precipitation events. It necessitates reviewing the Probable Maximum Floods (PMFs) considered for planning and designing large dams and updating them for different speculated climate change scenarios to determine the projected future changes in dam break risk. Global initiatives, such as the Paris Agreement, are focused on developing strategies to limit the increase in global temperatures well below 2°C (preferably 1.5°C) above pre-industrial levels by 2050. However, significant discrepancies have been identified between the current global greenhouse gas emissions trajectory and the reductions needed in emissions to achieve the Paris Agreement's target. To bridge this gap, geoengineering climate intervention methods such as Stratospheric Aerosol Injection (SAI) and Solar Dimming (SD) have been proposed as potential solar radiation management (SRM) options to offset climate change effects. The latest Geoengineering Model Intercomparison Project (GeoMIP6) provides simulations from a suite of climate model experiments designed to assess the effect of potential SRM methods, including SAI and SD. To shed light on the effectiveness of geoengineering, this study assesses the impact of the current generation climate models (from Coupled Model Intercomparison Project Phase 6, CMIP6) and geoengineering models (from GeoMIP6) on Probable Maximum Precipitation (PMP) and the corresponding Probable Maximum Flood (PMF) at a typical large dam (Hemavathi) located in the Cauvery River basin in India. The current PMF of the dam is compared with future projections of the same derived corresponding to a CMIP6 high forcing scenario (SSP585) and two GeoMIP (G6sulphur and G6solar) scenarios. For both near and far future periods, the PMF hydrograph’s peak for the SSP585 scenario (GeoMIP6 scenarios) is significantly (marginally) greater than that of the current PMF of the dam. It indicates that geoengineering methods can offset climate change's impact on PMP and the corresponding PMF (depicting hydrological risk) at dams, which is of significance as worldwide many large dams have completed their design life.