Development of sea level rise scenarios for climate change assessments of the Mekong Delta, Vietnam

AbstractNatural resources of the Mekong River are essential to livelihood of tens of millions of people. Previous studies highlighted that upstream hydro-infrastructure developments impact flow regime, sediment and nutrient transport, bed and bank stability, fish productivity, biodiversity and biology of the basin. Here, we show that tidal amplification and saline water intrusion in the Mekong Delta develop with alarming paces. While offshore M2 tidal amplitude increases by 1.2–2 mm yr−1 due to sea level rise, tidal amplitude within the delta is increasing by 2 cm yr−1 and salinity in the channels is increasing by 0.2–0.5 PSU yr−1. We relate these changes to 2–3 m bed level incisions in response to sediment starvation, caused by reduced upstream sediment supply and downstream sand mining, which seems to be four times more than previous estimates. The observed trends cannot be explained by deeper channels due to relative sea level rise; while climate change poses grave natural hazards in the coming decades, anthropogenic forces drive short-term trends that already outstrip climate change effects. Considering the detrimental trends identified, it is imperative that the Mekong basin governments converge to effective transboundary management of the natural resources, before irreversible damage is made to the Mekong and its population.

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Impacts of Human Activity and Global Changes on Future Morphodynamics within the Tien River, Vietnamese Mekong Delta

Water ◽

10.3390/w12082204 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2204

Author(s):

Christian Jordan ◽

Jan Visscher ◽

Nguyen Viet Dung ◽

Heiko Apel ◽

Torsten Schlurmann

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Human Activity ◽

Mekong Delta ◽

Mining Activity ◽

Baseline Scenario ◽

Sand Mining ◽

Future Period ◽

Erosion And Deposition

The hydro- and morphodynamic processes within the Vietnamese Mekong Delta are heavily impacted by human activity, which in turn affects the livelihood of millions of people. The main drivers that could impact future developments within the delta are local stressors like hydropower development and sand mining, but also global challenges like climate change and relative sea level rise. Within this study, a hydro-morphodynamic model was developed, which focused on a stretch of the Tien River and was nested into a well-calibrated model of the delta’s hydrodynamics. Multiple scenarios were developed in order to assess the projected impacts of the different drivers on the river’s morphodynamics. Simulations were carried out for a baseline scenario (2000–2010) and for a set of plausible scenarios for a future period (2050–2060). The results for the baseline scenario indicate that the Tien River is already subject to substantial erosion under present-day conditions. For the future period, hydropower development has the highest impact on the local erosion and deposition budget, thus amplifying erosional processes, followed by an increase in sand mining activity and climate change-related variations in discharge. The results also indicate that relative sea level rise only has a minimal impact on the local morphodynamics of this river stretch, while erosional tendencies are slowed by a complete prohibition of sand mining activity. In the future, an unfavourable combination of drivers could increase the local imbalance between erosion and deposition by up to 89%, while the bed level could be incised by an additional 146%.

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Future sediment dynamics in the Mekong Delta floodplains: Impacts of hydropower development, climate change and sea level rise

Global and Planetary Change ◽

10.1016/j.gloplacha.2015.01.001 ◽

2015 ◽

Vol 127 ◽

pp. 22-33 ◽

Cited By ~ 72

Author(s):

Nguyen Van Manh ◽

Nguyen Viet Dung ◽

Nguyen Nghia Hung ◽

Matti Kummu ◽

Bruno Merz ◽

...

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Mekong Delta ◽

Sediment Dynamics ◽

Hydropower Development ◽

And Sea Level

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Modelling climate change impacts on the flood pulse in the Lower Mekong floodplains

Journal of Water and Climate Change ◽

10.2166/wcc.2010.008 ◽

2010 ◽

Vol 1 (1) ◽

pp. 67-86 ◽

Cited By ~ 98

Author(s):

K. Västilä ◽

M. Kummu ◽

C. Sangmanee ◽

S. Chinvanno

Keyword(s):

Climate Change ◽

Water Balance ◽

Sea Level Rise ◽

Sea Level ◽

Mekong Delta ◽

Flood Pulse ◽

Water Levels ◽

Infrastructure Development ◽

Ecosystem Productivity ◽

Basin Water

The flood pulse is a key element characterizing the hydrology of the Mekong River and driving the high ecosystem productivity in the Lower Mekong floodplains, both in the Cambodian lowlands and the Mekong Delta in Vietnam. This paper assesses the impacts of climate change, both in terms of changed basin water balance and sea level rise, on the Lower Mekong flood pulse. The impacts were simulated by a three-dimensional hydrodynamic model using the projected changes in sea level and the Mekong mainstream discharge under the influence of climate change as boundary conditions. The model simulations projected that average and maximum water levels and flood duration increase in 2010–2049. The most consistent and notable changes occurred in the average and dry hydrological years. Sea level rise had the greatest effects in the Mekong Delta, whereas the impacts of changed basin water balance were more notable in the upper areas of the Mekong floodplains. The projected impacts were mostly opposite to those resulting from regional water infrastructure development. Higher and longer flooding could cause damage to crops, infrastructure and floodplain vegetation, and decrease the fertile land area. On the other hand, it might boost ecosystem productivity and enhance dry season water availability.

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Some methods on flood inudation mappings for Long An province under climate change and sea level rise

Science and Technology Development Journal ◽

10.32508/stdj.v16i1.1385 ◽

2013 ◽

Vol 16 (1) ◽

pp. 32-39

Author(s):

Quan Hong Nguyen

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Mekong Delta ◽

Flood Inundation ◽

Gis Analysis ◽

Adaptation Measures ◽

Inundation Maps ◽

Inundation Map ◽

And Sea Level

Mapping flood inundation can be done by different methods, of which GIS analysis and flood modeling can be considered as the most popular ones. The modeling approach often requires more data but produce more detail results comparing to the GIS. Based on the assessment of current applied methods for building flood inundation map in the Mekong delta provinces in general and Long An in particular as well as based on some recent results of using GIS, 1 D ISIS model and 1-2D Mike Flood model applied in Long An province, the author show advantages as well as disadvantages of each methods and especially the results’ confidence. As the result, the author presents some challenges in mapping flood inundation maps under climate change and sea level rise. Integrating hydraulic construction (e.g. dyke, sluice, storage areas) and adaptation measures in the current and future in the analysis are typical challenges.

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Climate Change and Sea Level Rise in the Mekong Delta

Coastal Disasters and Climate Change in Vietnam ◽

10.1016/b978-0-12-800007-6.00009-5 ◽

2014 ◽

pp. 199-218 ◽

Cited By ~ 10

Author(s):

To Quang Toan

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Mekong Delta ◽

And Sea Level

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Assessing the impact of sea level rise due to climate change on seawater intrusion in Mekong Delta, Vietnam

Water Science & Technology ◽

10.2166/wst.2018.038 ◽

2018 ◽

Vol 77 (6) ◽

pp. 1632-1639 ◽

Cited By ~ 28

Author(s):

D. T. Vu ◽

T. Yamada ◽

H. Ishidaira

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Sea Water ◽

Mekong Delta ◽

Baseline Period ◽

Salinity Intrusion ◽

1D Modeling ◽

The Impact ◽

Regional Rainfall

Abstract In the context of climate change, salinity intrusion into rivers has been, and will be, one of the most important issues for coastal water resources management. A combination of changes, including increased temperature, change in regional rainfall, especially sea level rise (SLR) related to climate change, will have significant impacts on this phenomenon. This paper presents the outcomes of a study conducted in the Mekong Delta of Vietnam (MKD) for evaluating the effect of sea water intrusion under a new SLR scenario. Salinity intrusion was simulated by one-dimensional (1D) modeling. The relative sea level projection was constructed corresponding to the RCP 6.0 emission scenario for MKD based on the statistical downscaling method. The sea level in 2050 is projected to increase from 25 cm to 30 cm compared to the baseline period (in 2000). Furthermore, the simulated results suggested that salinity greater than 4 g/l, which affects rice yield, will intrude up to 50–60 km into the river. Approximately 30,000 ha of agricultural area will be affected if the sea level rise is 30 cm.

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