Multivariate Approach Reveals a Higher Likelihood of Compound Heat
Stress-Pluvial Floods in Urban India
Abstract
The cascade hazard, heat stress (preconditioned) and heavy rainfall
(response) in close succession have become frequent in several areas of
the globe, causing critical infrastructure failures. Although some
regions of South Asia witness deadly humid heat stress, little is known
about the linkage of humid heat stress (HHS; high temperature
compounded by humidity) versus record rainfall and cascade hazard due to
compound (same or lagged-day) occurrences of both extremes. We leverage
ground-based meteorological records from 1970-2018 to analyze the risk
of extreme precipitation preceded by heat stress over selected urban
locations of India using a multivariate conditional-probability
approach. We show that humid heat is likely to intensify the
extreme rainfall, especially during the core monsoon (June-September)
season. This phenomenon is associated with moisture convergence and
large upper tail distributions of peak precipitation over several sites.
Our insights to compound flood hazard would benefit (re)-insurance and
flash flood forecast, devising adaptations.