Understanding and Modeling Variability of Space-Time Hydroclimate and Extremes

Balaji Rajagopalan

University of Colorado Boulder

Tuesday, May 20, 2025, 2:00 pm MT
DSRC Room GC402

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Abstract

In recent decades, the frequency and magnitude of hydroclimate (precipitation, temperature, streamflow etc.) extremes are exhibiting increasing trends across the globe. They inflict destructive punches on the infrastructure, ecology and, consequently, on socio-economy of countries, besides taking many human lives. This impact is particularly severe for developing countries like India. The recent line of extreme flooding events (Chennai floods late last year) over India underscores this. Thus, to effectively mitigate the negative impacts of these extreme events, we need to understand and model their space-time variability along with their attendant uncertainties. For, this will enable risk-based management, planning and adaptation for a range of sectors – infrastructure, water resources, public health, agriculture etc. and help mitigate the risks from these extremes. With this driving motivation we in our group continue to develop statistical learning models for these hydroclimate variables. Bayesian hierarchical models (BHM) and tree-based methods are the two main modeling frameworks that we adapted and developed. My talk will showcase the applications of these methods to a variety of problems - stochastic space-time weather generation, precipitation extremes in space and time, streamflow on a river network, satellite and ground observations, Arctic sea-ice retreat, Colorado River flow variability and, paleoclimate reconstructions. The potential extensions of these modeling approaches for other extremes such as droughts, precipitation, and temperature spells, etc., and applications of these for a suite of disaster mitigation, management and planning efforts will be readily apparent.

Bio: Professor Rajagopalan Balaji is a Professor in the Department of Civil, Environmental and Architectural Engineering (CEAE), a Fellow of Cooperative Institute of Research in Environmental Sciences (CIRES), CU Boulder and the former Chair of the Department during 2014 – 2022. He pursues research in diverse interdisciplinary areas spanning – hydro-climatology, water resources management, Indian summer monsoon, paleoclimate, large scale statistical analysis and modeling for applications to water and wastewater quality, construction safety, building energy efficiency and others. He publishes widely in leading and prestigious peer-reviewed journals. He was elected Fellow, American Geophysical Union, in 2018, of American Society of Civil Engineers, and awarded the Fulbright-Kalam Climate Fellowship in 2023, all prestigious honors.