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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: [email protected])
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
6 7 8 9 10 110
5,00010,00015,00020,00025,00030,00035,00040,000
Historical mean monthly dischargeCLC1CLC2
Month
Mon
thly
ave
rage
dis
char
ge (m
3s-1
)
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
Lessons learnt
PAST figure:
Discharge
distribution
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.
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
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. USD28/04/2016
• … 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???
Hydrological zones in the Delta
Flood zones
Fresh-water zones
Saline-influenced zones
Hydrological alteration fromwater 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
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
J J A S O N D0
10,00020,00030,00040,00050,00060,00070,00080,00090,000
100,000
Recorded events (1991, 1996, 1997, 2000)Projected events (2019, 2021, 2046, 2047)
Daily
dis
char
ge (m
3s-1
)
….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].
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
- 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
• Rice yields are negatively correlated with higher temperaturesCurrently, 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 + FertilizerCO2
Changing farming systems
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, …)
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
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
Sinking Delta – the Rise and Fall project
… of great challenge…
Interaction between components are very
much unknown
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/
Mekong Observatory – to trace sources of water from the Mekong river
• To identify strategies to deal with trans-boundary issues in the Mekong Basin
Bringing stakeholders together:- Scientists (IT and
environmental experts)- Government and farmers
Sharing information Supporting decisions Improving livelihoods
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).
Comparison of perceptions
Modification ofresponses and
modelled parameters
Can the gap(s) between local- and expert knowledge about climate change adaptation be
bridged?
M-POWER website: http://www.mpowernetwork.org/index.html
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)
Field-based experimentsLEARNING TOGETHER WITH FARMERS
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
Field surveys
Thank you very much,
Van Pham Dang Tri, Assoc. Prof., Ph.D.College of Environment and Natural Resources
(email: [email protected])
