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Future coastal flooding scenarios for the world's largest mega-city
M. De Dominicis, J. Wolf, S. Jevrejeva, P. ZhengZ. Hu
10th UK FVCOM users’ workshop 27th - 28th November 2019, Liverpool
• The Pearl River Delta in the South China Sea is densely populated, fast-developing, and the most
urbanised delta in the world. As it is very low-lying, cities here, like Guangzhou, are the most vulnerable to
sea level rise.
• ANCODE aims to better understand the potential for re-introducing nature-based coastal defences, namely
mangroves and oyster reefs, into such environment.
Applying Nature-based COastal DEfence
in the Pearl River Delta: the ANCODE projectfunded by EPSRC under the NEWTON programme “Sustainable Deltas”
In collaboration with Sun Yat-Sen university (China) and NIOZ (Netherlands)
National Oceanography Centre
Sea level rise by 2100
The changes in regional sea level are quantified in this
work by using probabilistic regional sea level
projections for selected scenarios of climate change. SEA LEVEL EXPANSION GLACIERS GREENLAND ANTARCTICA LAND WATER
Jevrejeva et al, 2016
GUANGZHOU SHENZEN
99th
95th
50th
99th
95th
50th
PROJECTION IN CHINA
GLOBAL PROJECTION
RCP8.5 RCP8.5
95th
50th
National Oceanography Centre
An FVCOM (Finite Volume Community Model) implementation for the South China
Sea and Pearl River Delta is used to understand how the rising mean sea level, tides
and storm surge can interact and affect coastal inundation in the Pearl River Delta.
Modelling the Pearl River Delta
Details…
- FVCOM 4.0
- 25 vertical sigma layer, uniform
- Tides: TPXO8.0, 13 components
M2,S2,N2,K2,K1,O1,P1,Q1,MF,MM,M4,MS4,MN4
- Bottom friction: uniform roughness length (0.001 m)
with minimum Cd=0.0025
- Grid: 85129 nodes - 140449 elements
- Time step: 0.1/0.2 s external mode (barotropic)/0.5/0.10
s internal mode (baroclinic)
- River discharge: annual/seasonal averages
National Oceanography Centre
Validation
4 Tide Gauges available with hourly resolution from U Hawaii Sea Level Centre:
Hong Kong 1962-01-01:2016-12-30
Macau 1978-01-01:1985-05-30
Zhapo 1975-01-01:1997-12-30
Shanwei 1975-01-01:1997-12-31
National Oceanography Centre
Validation
Changes in tides for wet and dry seasons under
4 different future sea level scenarios: 0.3m, 0.5m, 0.9m and 2.1m
(i.e. the 50th and 95th percentile for 2050 and 2100).
Changes in surge for the 2 latest and strongest typhoons hitting the PRD under
the same 4 future sea level scenarios.
CH
AN
GE
SIN
M
SL
CH
AN
GE
SIN
T
IDE
S2(M2+S2)
M2+O1+K1
Storm tracks
International Best Track Archive for Climate Stewardship (IBTrACS) - NOAA
Typhoon Hato
August 2017
ERA5 reanalysis
Typhoon Hato
August 2017
Holland’s windsCH
AN
GE
S
INS
UR
GE
CH
AN
GE
S
INS
UR
GE
Typhoon Mangkhut
September 2018
Holland’s winds
• In a delta environment, sea level rise is not simply added to extreme water levels, but
introduces feedbacks on tides and surge levels
• Amplification of tides could exceed 0.5 m for 2.1 sea level rise and should be
considered when planning future coastal defences.
• Sea level rise can induce a reduction of surge level of up to 0.5 m ins ome coastal areas
for typhoons like Hato or Mangkhut
Conclusions & Future plans
Conclusions & Future plans
• Our final aim is to use the Pear River Delta FVCOM model to optimise the location of
mangroves spaces for defence, under contrasting scenarios of climate change.
• This requires (ideally):
• Wave-current-sediment coupled models (FVCOM)
• Vegetation Model (to be introduced in FVCOM)
Making Sense of Changing Seas
Thank you