Rise and Fall: strategies for the subsiding and urbanising Mekong Delta (Vietnam) facing increasing salt water intrusion

The research aims to develop sustainable strategies for groundwater extraction and management, and to understand and quantify land subsidence and salt water inflow in the rapidly urbanising Mekong Delta in Vietnam.

Key audiences to be targeted during the research are:

  • Co-investigators in Vietnam (Can Tho University, Division for Water Resources Planning and Investigation for the South of Vietnam).
  • Water authorities who take decisions on the management of the resource.
  • Water managers, awareness promotors (national NGO’s, governmental organizations), educators, lecturers

PROJECT WEBSITE

Consortium

Project leader: Prof. P. (Piet) Hoekstra (Utrecht University)

Consortium partners: T.T. Long (Southern Institute for Water Resources Research (SIWRR), F. van Geer (Geological Survey of the Netherlands (TNO), G. Oude Essink (Deltares), B.T. Vuong (Division of Water Resources Planning and Investigation for the South of Vietnam), H.T. Nguyen (Can Tho University)

Consortium partners (institutions): Southern Institute for Water Resources Research (SIWRR), Geological Survey of the Netherlands (TNO), Deltares, Division of Water Resources Planning and Investigation for the South of Vietnam, Can Tho University

Progress

Our Rise and Fall project aims to enhance the capabilities of individuals and organisations to develop sustainable strategies for dealing with groundwater extraction, land subsidence and salt water intrusion in the increasingly urbanising Mekong Delta. A new Integrated Delta Model (IDM) is developed, linking surface water, groundwater and geo-mechanical models, to analyse the interrelated character of groundwater extraction, subsidence levels and salt water intrusion. The IDM will be an important tool for local and regional managers and stakeholders to analyse and develop adequate water management strategies based on development scenarios.

First modeling results suggest that present fresh groundwater resources in the delta had infiltrated in the Mekong Delta in the period of low sea level, more than 20.000 years ago. Present infiltration rates are much smaller than in the past due to the Late Pleistocene and Holocene deposits creating a resistant top layer. This reduces infiltration and recharge of fresh groundwater. The current management policy to use a lot of the groundwater resources will clearly lead to a depletion and degradation of these resources. Our 3D geological subsurface model of the entire Mekong Delta, based on an extensive database of geological and geomechanical data, is combined with hydrological data to develop the first version of a geohydrological model. As a next step, this model was linked to a subsidence model to obtain first order estimates of subsidence rates and patterns in the Mekong Delta (including Ho Chi Minh City, HCMC) due to groundwater extraction. The results indicate that large parts of the delta and major areas in HCMC are or will suffer from relatively high subsidence rates. Meanwhile, the prolonged dry period of 2016, caused by a relatively strong El Niño has resulted in a record-high salt water intrusion in the downstream river branches of the Mekong Delta, an effect that will be further enhanced by future subsidence.

Summary

The project aims to enhance the capabilities of individuals and organisations to develop sustainable strategies for dealing with groundwater extraction, land subsidence and salt water intrusion in the increasingly urbanising Mekong Delta (Vietnam). We will enlarge the knowledge base of stakeholder (including policymakers, water managers and scientists) and work with them to develop and implement innovative tools and technologies in practice and policy.

A new integrated delta model will be developed linking surface water, groundwater and geo-mechanical models, to analyse the interrelated character of groundwater extraction, subsidence levels and salt water intrusion. Together with stakeholders the integrated model will be constructed and applied to quantify the effects of water management strategies in the Mekong Delta. Stakeholders will analyse and develop adequate strategies by simulating and demonstrating the effects of development scenarios and policy recommendations, such as expressed in the Mekong Delta Plan (2013).

Products

Scientific article

Publication meant for a broad audience

Professional publication

Publical information

Details

Project number

W 07.69.105

Main applicant

Prof. dr. P. Hoekstra

Affiliated with

Universiteit Utrecht, Faculteit Geowetenschappen, Departement Aardwetenschappen

Team members

Dr. R.A.C. Dam, Dr. C. Dieperink, R. Dierx, Dr. G. Erkens, Prof. dr. ir. F.C. van Geer, Prof. dr. P. Hoekstra, M. Lindhart, Dr. T.T. Long, Prof. dr. H. Middelkoop, P.S.J. Minderhoud MSc, Dr. H.S. Otter, Dr. ir. G.H.P. Oude Essink, Dr. E. Stouthamer, Dr. T.Q. Toan, Dr. V.P.D. Tri, Dr. N.H. Trung, Mr. H.P. Van, Dr. M. van der Vegt, Dr. B.T. Vuong

Duration

01/09/2014 to 31/08/2019