The world’s population living on low-lying deltas is increasingly vulnerable to flooding, whether
from intense rainfall, rivers or from hurricane-induced storm surges. High-resolution SRTM and
MODIS satellite data along with geo-referenced historical map analysis allows quantification of
the extent of low-lying delta areas and the role of humans in contributing to their vulnerability.
Thirty-three major deltas collectively include ~26,000 km2 of area below local mean sea level and
~96,000 km2 of vulnerable area below 2 m a.s.l. The vulnerable areas may increase by 50% under
projected 21st Century eustatic sea level rise, a conservative estimate given the current trends in
the reduction in sedimentary deposits forming on the surface of these deltas. Analysis of river
sediment load and delta topographical data show that these densely populated, intensively farmed
landforms, that often host key economic structures, have been destabilized by human-induced
accelerated sediment compaction from water, oil and gas mining, by reduction of incoming
sediment from upstream dams and reservoirs, and from floodplain engineering.