{"691371":{"#nid":"691371","#data":{"type":"event","title":"EAS Seminar Series - Dr. Donghui Xu","body":[{"value":"\u003Cp\u003EEarth System Models (ESMs) are essential tools for simulating global water and energy cycles and supporting water resource assessments. However, the accuracy of their hydrologic simulations is often limited by parametric uncertainties and process simplifications. In this presentation, I will present my research efforts to enhance the representation of hydrologic and hydrodynamic processes in a fully coupled ESM. However, its coarse resolution (e.g., 50 km \u2013 100 km) further limits their ability to simulate urban flooding dynamics at the scale relevant to human activities and infrastructure. To address this challenge, I contributed to the development of a new river dynamics core that solves two-dimensional shallow water equations, enabling efficient high-fidelity hydrodynamic simulations (e.g., 30m) at large scales. I will demonstrate this new capability using a case study of compound flooding driven by Hurricane Irene. By coupling with a regionally refined atmospheric model, a two-dimensional barotropic ocean model, and a high-resolution land surface model within an ESM, the multi-scale modeling framework captures unprecedented details of flooding processes in complex urban environments. Despite these advances, such actionable-scale flooding simulations remain computationally infeasible for real-time forecasting. To further improve the model efficiency, I proposed a real-time flooding forecast framework based on a machine learning based surrogate model trained on outputs from the physical flooding model prior to flood events. During an event, the surrogate model can rapidly predict flooding extent using forecasted precipitation within seconds on a low-end computer, while also quantifying uncertainties associated with precipitation forecasts.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 12-12:30 PM, ES\u0026amp;T Atrium\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EEarth System Models (ESMs) are essential tools for simulating global water and energy cycles and supporting water resource assessments. However, the accuracy of their hydrologic simulations is often limited by parametric uncertainties and process simplifications. In this presentation, I will present my research efforts to enhance the representation of hydrologic and hydrodynamic processes in a fully coupled ESM. However, its coarse resolution (e.g., 50 km \u2013 100 km) further limits their ability to simulate urban flooding dynamics at the scale relevant to human activities and infrastructure. To address this challenge, I contributed to the development of a new river dynamics core that solves two-dimensional shallow water equations, enabling efficient high-fidelity hydrodynamic simulations (e.g., 30m) at large scales. I will demonstrate this new capability using a case study of compound flooding driven by Hurricane Irene. By coupling with a regionally refined atmospheric model, a two-dimensional barotropic ocean model, and a high-resolution land surface model within an ESM, the multi-scale modeling framework captures unprecedented details of flooding processes in complex urban environments. Despite these advances, such actionable-scale flooding simulations remain computationally infeasible for real-time forecasting. To further improve the model efficiency, I proposed a real-time flooding forecast framework based on a machine learning based surrogate model trained on outputs from the physical flooding model prior to flood events. During an event, the surrogate model can rapidly predict flooding extent using forecasted precipitation within seconds on a low-end computer, while also quantifying uncertainties associated with precipitation forecasts.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 12-12:30 PM, ES\u0026amp;T Atrium\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Actionable-scale Flooding Simulations with a Multi-scale Modeling Framework"}],"uid":"36678","created_gmt":"2026-07-31 14:08:48","changed_gmt":"2026-07-31 14:24:35","author":"tbuchanan9","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2026-09-17T11:00:00-04:00","event_time_end":"2026-09-17T12:00:00-04:00","event_time_end_last":"2026-09-17T12:00:00-04:00","gmt_time_start":"2026-09-17 15:00:00","gmt_time_end":"2026-09-17 16:00:00","gmt_time_end_last":"2026-09-17 16:00:00","rrule":null,"timezone":"America\/New_York"},"location":"EST L1205","extras":["free_food"],"hg_media":{"680737":{"id":"680737","type":"image","title":"Xu Headshot","body":null,"created":"1785507154","gmt_created":"2026-07-31 14:12:34","changed":"1785507154","gmt_changed":"2026-07-31 14:12:34","alt":"Xu Headshot","file":{"fid":"265044","name":"Xu-Headshot.jpg","image_path":"\/sites\/default\/files\/2026\/07\/31\/Xu-Headshot.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2026\/07\/31\/Xu-Headshot.jpg","mime":"image\/jpeg","size":1021270,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2026\/07\/31\/Xu-Headshot.jpg?itok=uN99W429"}}},"media_ids":["680737"],"related_links":[{"url":"https:\/\/scholar.google.com\/citations?user=D1cho0wAAAAJ\u0026hl=en","title":""}],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}},"691370":{"#nid":"691370","#data":{"type":"event","title":"EAS Seminar Series - Dr. Ignacio Sepulveda","body":[{"value":"\u003Cp\u003EThe seminar will highlight three research efforts developed in Chile during my stay in 2025. First, through collaborations with private organizations, we measured the Kamchatka tsunami as it entered the Valdivia River Estuary in Chile. These unique ADCP measurements included currents and water levels, providing rare observations of tsunami-river-tide interactions. Building on the success of this deployment, we installed two permanent monitoring stations in the Valdivia River to continuously measure water levels, waves, temperature, salinity, and dissolved oxygen.\u003C\/p\u003E\u003Cp\u003ESecond, I introduce the \u003Cem\u003ETRIDENT \u003C\/em\u003Emodel (Tides and Rivers Influencing the Dynamic Evolution of Nearshore Tsunamis), a modeling framework designed to simulate the coupling between tsunamis, tides, and river flows. The coupled model is designed for estuaries, tidal channels, and fjords, and it addresses key challenges when simulating these interactions.\u003C\/p\u003E\u003Cp\u003EFinally, I will present results from a study that links dispersive tsunami wave trains visible in satellite imagery to near-trench earthquake rupture. By analyzing tsunami dispersion in the near-source wave field, this approach provides a new observational footprint for constraining source processes that improves resolving power near the trench compared with traditional seismic, geodetic, and tsunami sensing technologies.\u003C\/p\u003E\u003Cp\u003ECollectively, these studies demonstrate complementary advances, from field deployment to coupled modeling for hazard prediction to remote-sensing-based discovery, that expand the toolkit for understanding and assessing tsunami hazards and risks.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 12-12:30 PM, ES\u0026amp;T Atrium\u003C\/p\u003E","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EThe seminar will highlight three research efforts developed in Chile during my stay in 2025. First, through collaborations with private organizations, we measured the Kamchatka tsunami as it entered the Valdivia River Estuary in Chile. These unique ADCP measurements included currents and water levels, providing rare observations of tsunami-river-tide interactions. Building on the success of this deployment, we installed two permanent monitoring stations in the Valdivia River to continuously measure water levels, waves, temperature, salinity, and dissolved oxygen.\u003C\/p\u003E\u003Cp\u003ESecond, I introduce the \u003Cem\u003ETRIDENT \u003C\/em\u003Emodel (Tides and Rivers Influencing the Dynamic Evolution of Nearshore Tsunamis), a modeling framework designed to simulate the coupling between tsunamis, tides, and river flows. The coupled model is designed for estuaries, tidal channels, and fjords, and it addresses key challenges when simulating these interactions.\u003C\/p\u003E\u003Cp\u003EFinally, I will present results from a study that links dispersive tsunami wave trains visible in satellite imagery to near-trench earthquake rupture. By analyzing tsunami dispersion in the near-source wave field, this approach provides a new observational footprint for constraining source processes that improves resolving power near the trench compared with traditional seismic, geodetic, and tsunami sensing technologies.\u003C\/p\u003E\u003Cp\u003ECollectively, these studies demonstrate complementary advances, from field deployment to coupled modeling for hazard prediction to remote-sensing-based discovery, that expand the toolkit for understanding and assessing tsunami hazards and risks.\u003C\/p\u003E\u003Cp\u003E*Refreshments: 12-12:30 PM, ES\u0026amp;T Atrium\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"From Observation to Prediction: A Year of Tsunami Science in Chile"}],"uid":"36678","created_gmt":"2026-07-31 14:00:29","changed_gmt":"2026-07-31 14:08:02","author":"tbuchanan9","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2026-09-24T11:00:00-04:00","event_time_end":"2026-09-24T12:00:00-04:00","event_time_end_last":"2026-09-24T12:00:00-04:00","gmt_time_start":"2026-09-24 15:00:00","gmt_time_end":"2026-09-24 16:00:00","gmt_time_end_last":"2026-09-24 16:00:00","rrule":null,"timezone":"America\/New_York"},"location":"EST L1205","extras":["free_food"],"hg_media":{"680736":{"id":"680736","type":"image","title":"Sepulveda Headshot","body":null,"created":"1785506800","gmt_created":"2026-07-31 14:06:40","changed":"1785506800","gmt_changed":"2026-07-31 14:06:40","alt":"Sepulveda Headshot","file":{"fid":"265043","name":"Sepulveda-Headshot.png","image_path":"\/sites\/default\/files\/2026\/07\/31\/Sepulveda-Headshot.png","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2026\/07\/31\/Sepulveda-Headshot.png","mime":"image\/png","size":1478324,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2026\/07\/31\/Sepulveda-Headshot.png?itok=5F-Jte4k"}}},"media_ids":["680736"],"related_links":[{"url":"https:\/\/ignaciosepu.wixsite.com\/sepulveda","title":""}],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}