Global assessment of flood impacts on emergency service provision to vulnerable populations, presently and under climate change

Flooding is a globally increasing and non-uniform hazard that is the leading cause of fatality and economic losses amongst all other natural disasters. Vulnerable populations are disproportionately affected by floods and rely on Ambulance and Fire & Rescue services for emergency assistance, rescue, recovery, and evacuation. However, flooded roads combined with short mandatory response times limit the potential emergency service accessibility and population coverage.

Global variations in flood-restricted emergency service provision and the potential for future changes are currently not well understood. Hence, a global analytical framework was created to determine the spatial, temporal, and demographic variability of emergency service provision during floods of various magnitudes under climate change. This includes fluvial and coastal flood hazards at 10- and 100-yr return periods for 2010 and 2050, under the climate scenarios RCP4.5 and RCP8.5. The framework enables accessibility, vulnerability, and hotspot analyses to identify the extent and distribution of emergency service area coverage and vulnerable population accessibility based on road network restrictions by floods (for specified 8- and 30-minute response times). Sensitivity analyses were also performed to investigate the influence of various future socio-economic and climate conditions on the analytical framework outcomes.

The main findings of this research include:

Asia and Africa are top hotspot continents (Bangladesh, Chad, Guyana, and Liberia are the most frequently reoccurring hotspot countries that co-occur for both Ambulance and Fire & Rescue services). These hotspots are locations of vulnerability to emergency service provision based on a correlation between large reductions in provision (service area coverage, accessibility to school facilities, and accessibility to vulnerable populations) and high scores from the ND-GAIN index of climate readiness and vulnerability.

Global emergency service accessibility decreases by 0.5-8% between 2010- and 2050-time horizons, by 0.1-1% between RCP4.5 and RCP8.5 climate scenarios, and by 0.1-6% between 10- and 100-yr flood hazard return periods, whereas the accessibility doubles between the 8- and 30- minute response times.

Globally, between the flood hazard types, it is identified that fluvial flooding causes a 5-9% greater reduction in the number of accessible populations than coastal flooding between the 2010 baseline and high-end 2050, RCP8.5, 100-year return period scenario (for Ambulance and Fire & Rescue services under 8- and 30-minute response times).

Global population accessibility is greater for Ambulance services than for Fire & Rescue services, largely due to the greater number and distribution of stations (and interactions with the flood hazards).

Under the 2010 baseline and 2050 high-end future scenarios (based on 8- and 30-minute response times), 27-58% of the global population is accessible to Ambulance services under the baseline scenario, reducing to 24-57% under coastal flooding, and 20-48% under riverine flooding. Comparatively, 14-35% of the global population is accessible by Fire services under the baseline scenario, reducing to 14-34% under coastal flooding, and 12-29% under riverine flooding.

For both present and future time horizons (between the 2010 baseline and 2050 riverine high-end scenario), Africa has the largest number of accessible at-risk children than elderly (as 33-433% more children are accessible than elderly individuals). Comparatively, Europe has the largest number of accessible at-risk elderly than children (as 7-92% more elderly individuals are accessible than children). This reflects current population demographics and future population projections.

Finally, using the Netherlands as a case study, a plausible worst-case future involving reductions in emergency service funding and centralisation (optimisation) of emergency responders into fewer mega hubs/specialised units results in a service area decrease of 9-10% for Ambulance services and 20-22% for Fire services, relative to the current (flood-restricted) service area. Comparatively, a best-case future involving emergency service funding investments and decentralisation (maximisation) via additional standby hubs results in a service area increase of 64-72% for Ambulance stations and 6-16% for Fire stations, relative to the current (flood-restricted) service area.

All storylines (non-probabilistic plausible future pathways based on long term global megatrends) reduce service area and accessible populations relative to the 2050-adjusted (present station distribution) non-flood accessible populations. This reduction is resultant of future flood footprints restricting a greater number of schools, stations, and land area, than additional stand-by hubs can compensate for.

This global analytical framework, with the highlighted geographical and temporal impacts on emergency service provision, offers a tool for (inter)national organisations and governments to shape real-world policies and plans about emergency responder coverage. This includes strategic planning of emergency service coverage for expected increases in flooding as well as investments in infrastructure and services, to maximise future benefits for most flood-vulnerable populations.