This presentation is part of the ProSPER.Net Young Researchers' School 2017 ‘Water Security for Sustainable Development in a Changing Climate’.

1. Climate change and impacts on
agriculture in the Vietnamese
Mekong Mekong Delta
Van Pham Dang Tri, Assoc. Prof., Ph.D.
College of Environment and Natural Resources
(email: vpdtri@ctu.edu.vn)

2. Content
- The international Mekong river
- Water crisis in the Vietnamese Mekong Delta (VMD)
- Food security vs. Climate change
- Ring dykes development vs. Food security
- Saline intrusion vs. Food security
- Sinking delta vs. sea level rise

3. 0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
6 7 8 9 10 11
Monthlyaveragedischarge(m3s-1)
Month
Historical mean monthly discharge CLC1 CLC2
Figure: Historical and projected mean monthly discharges at Kratie; CLC1
and CLC2: Climate Change Scenario 1 and 2, respectively; the standard
deviation bars of the historical and projected mean monthly discharges according
to CLC1 and 2 were presented from left to right.
Figure: Measured sea levels in the East (A) and West (B) Sea on the selected
dates.
Hydrology of the VMD
Main-river flow
Over-bank flow

4. The International Mekong River
Threatened by:
 Hydrological condition modifications driven by climate change;
 Socio-economic development in agriculture, forestry, industry and
energy.
Consequent impacts:
• Flows modified – flood, saline intrusion and sediment loads, both in
terms of magnitude and time;
• Changes in sediment load and increasing water pollution
• Damages in different socio-economic sectors;
• Existing agro-ecological zones – physically distorted.

5. Climate Change in the Mekong Basin
Figure: Viet Nam, winter mean temperature, 1901
to 1998. (Source: Schaefer. 2002)
Figure: Viet Nam, summer mean temperature, 1901
to 1998. (Source: Schaefer. 2002)
Temperature increases in March, April and May

6. Water crisis
in the Vietnamese Mekong Delta
http://vnexpress.net/infographic/thoi-su/dong-bang-song-cuu-long-bi-xam-nhap-man-the-nao-3363559.html
22/02/2016
Damages: 5,572 B. VND
~ 450 M. USD
28/04/2016

7. • … after this servere drought year - 2016 (given
impacts of the El Nino) wet years of heavy rain and
fluvial floods (given impacts of La Nina) are
expected
Water crisis
– the shifting patterns
• What is the magnitude of the flood?
• How will upstream hydro-power dams be operated?
• Recently, saline intrusion is of great concerns
• WHAT ARE EXPECTED DAMAGES???

8. Hydrological zones in the Delta
Flood zones
Fresh-water zones
Saline-influenced zones

9. Hydrological alteration from
water infrastructure development
-Great impact on the natural
hydrological regime
-Spatial distribution of flooding
 Increase the risk of future
conflicts among region, economic
sectors, and the ecological values
Thanh, D.D., T.A. Cochrane, M.E. Arias, P.D.T. Van, T. de Vries (2016). Hydrological alterations from water
infrastructure development in the Mekong floodplains. Hydrological Processes, In proof. http://doi:
10.1002/hyp.10894
Buffer upstream
dam impacts to the
VMD
Flood prevention
structures

10. With the sea level rise, the upstream flood would
be extended further to the sea.
The proportion of discharge loaded
along the Mekong and Bassac
would be heavily modified!
Less fresh-water entering
the Bassac especially if
the sharp-hydrograph in
Kratie occurred!
Significant modification of the eco-
hydrological conditions of the vast
Ca Mau Peninsula
2000 Future
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
J J A S O N D
Dailydischarge(m3s-1)
Recorded events (1991, 1996, 1997, 2000)
Projected events (2019, 2021, 2046, 2047)
….among many others
(e.g. river morphology)
Future flood simulations
Van, P.D.T. et al., 2012. A study of the climate change impacts on fluvial flood propagation in the Vietnamese
Mekong Delta. Hydrology and Earth System Sciences, 16(12), pp.4637–4649. Available at: http://www.hydrol-
earth-syst-sci.net/16/4637/2012/ [Accessed February 21, 2013].

11. Dykes built – multi-fold impacts
- Current management of the full dyke network has been successful
in promoting triple cropping rice cultivation, but this practice
prevents sediment deposition and future sediment loads are also
now under great threat
Chapman, A.D., S.E. Darby, H.M. Hong, E.L. Tompkins and T.P.D. Van (2016). Adaptation and development trade-
offs: fluvial sediment deposition and the sustainability of rice-cropping in An Giang Province, Mekong Delta.
Climate Change, 1 – 16. http://10.1007/s10584-016-1684-3
- River-borne sediments have
significant economic value: i)
nutrients-bound sedimet; and, (ii)
maintaining land above sea-level
- Without a continuing supply of
sediment triple-cropping rice-
cultivation will not continue to be
sustainable or profitable over the
next 10-20 years

12. - The economic value of sediment as a free fertiliser is particularly
important to poorer farmers who are otherwise at significant risk of
debt due to fluctuations in artificial fertiliser prices
Chapman, A.D., S.E. Darby, H.M. Hong, E.L. Tompkins and T.P.D. Van (2016). Adaptation and development trade-
offs: fluvial sediment deposition and the sustainability of rice-cropping in An Giang Province, Mekong Delta.
Climate Change, 1 – 16. http://10.1007/s10584-016-1684-3
- A simple adaptation, to allow full
inundation in years of high flood,
would increase sediment deposition
and greatly increase the
sustainability of rice agriculture in the
face of future environmental change
- If sediment excluding triple-cropping
continues, financial support will need
to be provided to help poorer
farmers cope with increases in
artificial fertiliser prices
Dykes built – multi-fold impacts

13. • Rice yields are negatively correlated
with higher temperatures
Currently, rice is being grown at its
upper temperature threshold, so any
further increases in temperature could
lead to declining yields
• Rising CO2 levels may offset yield
losses from higher temperatures
- but that isn't guaranteed
- rising CO2 projections are less
confident than rising temperature
projections
• Any yield losses related to temperature
cannot be offset by adding more
fertilizer or water.
Rice productivity vs. Climate change
C. Kontgis, A. Schneider, M. Ozdogan, C. Kucharik, P.D.T. Van, H.D. Nguyen, J. Schatz (in progress). Climate
change impacts on rice productivity in the Mekong River Delta. Agricultural and Forest Meteorology.
Yield
Temperature
Water +
Fertilizer
CO2

14. Current salinity control
systems’ intakes
SLR 14cm, upstream
discharge reduce 11% (Without
upstream agriculture
development)
SLR 20cm, upstream
discharge reduce 38%
(With upstream
agriculture
development)
Future issues:
Sea level rise + Upstream discharge reduce scenario
• Reduce of upstream flow  reduce of sedimentation and increase salinity intrusion:
– Reduce/disable the efficiency of the existing salinity control projects
– Increase input costs (fertilizer, pesticide, …)

15. Responding to rising sea levels in the
Vietnamese Mekong Delta
Saline intrusion: Modelling vs. Actual
Smajgl, A., Toan, T. Q., Nhan, D. K., Ward, J., Trung, N. H., Tri, L. Q., … Vu, P. T. (2015). Responding to rising sea
levels in the Mekong Delta. Nature Climate Change, 5(2), 167–174. http://doi.org/10.1038/nclimate2469

16. Responding to rising sea levels in the
Vietnamese Mekong Delta
• An ensemble of hard and soft
policies is likely to provide the
most effective results for
people’s livelihoods in the VMD.
• The consequences of policy
deliberations are likely to be felt
beyond the VMD as levels of rice
cultivation there also affect
national and global food security.
Smajgl, A., Toan, T. Q., Nhan, D. K., Ward, J., Trung, N. H., Tri, L. Q., … Vu, P. T. (2015). Responding to rising sea
levels in the Mekong Delta. Nature Climate Change, 5(2), 167–174. http://doi.org/10.1038/nclimate2469

17. Sinking Delta
– the Rise and Fall project
… of great
challenge…
Interaction between
components are very
much unknown

18. Mekong Observatory – to trace sources
of water from the Mekong river
• To trace sources of water (and
other pollutants) ending up in the
Delta
• To identify strategies to deal
with trans-boundary issues in
the Mekong Basin
http://www.globalrivers.org/

19. Mekong Observatory – to trace sources
of water from the Mekong river
• To identify strategies to deal
with trans-boundary issues in
the Mekong Basin

20. Bringing stakeholders together:
- Scientists (IT and
environmental experts)
- Government and farmers
 Sharing information
 Supporting decisions
 Improving livelihoods

21. Climate change adaptation from local- and expert knowledge
in the coastal area of the Vietnamese Mekong Delta
Climate change (CC) is an on-going process of increasingly greater
concern for people living in the low-lying coastal areas of Asia
including the Mekong Region.
+ Different scientific studies  to understand the possible trends
and mechanisms of changes and vulnerabilities in the Vietnamese
Mekong Delta (VMD) (Figure 1), including numerical modelling.
+ Local communities in the VMD - subjected to seasonally varying
flows and hydrological conditions and already developed adaptation
mechanisms to cope with such variability.
This study – to create a mechanism to bridge gaps between the
types of knowledge generated from different sources i.e. local and
expert knowledge  bringing them together effectively leads to more
appropriate adaptation strategies to CC in the coastal area of the
VMD.
The study is expected to encourage scientists from different fields
and local stakeholders to work together to improve livelihoods of local
residents under variable and changing climates, especially in the most
vulnerable areas affected by sea level rise and changes in upstream
river flow.
Figure 1: The study river network in the Vietnamese Mekong Delta.
Figure 2: Study framework; CCA: Climate change adaptation.
EXPECTED RESULTS
(1) Scenarios of future climate patterns and possible impacts.
(2) Suitable sets of adaptation techniques (from the local and expert knowledge).
(3) Suitable approaches to bridge the gap(s) between the local and expert knowledge.
(4) Educational material on climate change adaptation for Undergraduate and Master
students of relevant topics in Can Tho University.
(5) A policy brief and peer-reviewed publication(s).
Can the gap(s) between local- and expert
knowledge about climate change adaptation be
bridged?
M-POWER website: http://www.mpowernetwork.org/index.html

22. Water resources management for rice farming systems
in the Vietnamese Mekong Delta in the context of climate change
INTRODUCTION
-The main focus of the study is to investigate water storage capacity in the
canals which can be used to irrigate rice during the water-shortage period,
when water in the main rivers would not be suitable for rice (i.e. saltilized).
METHODOLOGY
- Based on the physical features of the study area (including: local weather,
canals system, existing farming system) and bio-characteristics of crops
(including: growing period and water demand at each growing stage), a
cause-and-effect loop model (between the demand and supply of water
during the crop season) will be developed.
EXPECTED RESULTS
- To increase water storage capacity in the canals to help crop pass the water-shortage
time caused by salinity intrusion.
- To provide assistance to local farmers and state agencies in the areas to adapt to new
climate patterns, especially during the shortage of freshwater resources.
Figure 4: Water cycle (a) and currently water in field and canal (b) in a rice farming system
Figure 2: Relationship between water in canals and rice-fields
(b)(a)
Figure 3:
Dynamic
system
models of
the water-
cycle in a
farming
system
Figure 1: Currently of the rice fields and sluices at Nga Nam (Soc Trang)

23. Field-based experiments
LEARNING TOGETHER WITH FARMERS

24. Who owns the benefits of
scientific research?
• Local stakeholders to be involved in
scientific research
• Meet requirements of local area
• Support strategies development plan of
the area
• …
Brainstorming issues and
possible strategies to sustain
development in the coastal part
of the Vietnamese Mekong Delta

25. Field surveys

26. Thank you very much,
Van Pham Dang Tri, Assoc. Prof., Ph.D.
College of Environment and Natural Resources
(email: vpdtri@ctu.edu.vn)