Agricultural land-use dynamics in the floodplains of the Vietnamese Mekong Delta: hydrodynamic implications on flood regimes and adaptation options

Dung Duc Tran

Research output: Thesisinternal PhD, WU

Abstract

Due to intensified rice production, induced by national food security policy, the floodplains in the upper parts of the Vietnamese Mekong Delta have changed in agro-ecology from a seasonal floodplain into a highly intensified rice production area. To enable intensified rice production, large-scale flood-control infrastructure has been built, particularly low dikes and high dikes, to control the water entering agricultural fields. As a result, the delta has become a primary contributor to Vietnam’s food security, and the delta’s high production has made Vietnam one of the world’s foremost rice exporters. However, this transformation has reduced the flood retention capacity of the delta, degraded land and water quality, and undermined delta ecosystem services.

The main aims of the research presented in this thesis were two: to identify the impacts of extensive construction of flood-control infrastructure on the flood dynamics of the delta and to explore adaptation options to maximize livelihood sustainability and ecological sustainability on the delta. An available 1D-quasi2D hydrodynamic model was developed for the delta system as a whole to simulate flood discharges and river water levels, considering four dike construction scenarios. Using a sustainable livelihood perspective, alternative farming systems were explored using multi-criteria analysis and cost-benefit analysis on the local scale, relying on multiple interviews with stakeholders operating under different types of dikes and at different locations on the floodplains. The next step was to elaborate on costs and benefits while shifting the focus to the delta scale, also considering various future flood-control scenarios.

As such, this study advances knowledge on the impacts of extensive flood-control infrastructure on hydrodynamic patterns and flood risk upstream and downstream in delta systems. The findings of this study suggest a need to develop flood-based land and water management strategies and farming systems, instead of continued expansion of high-dike infrastructure and related farming systems. Indeed, this study found higher economic and environmental returns to the low-dike farming systems in the long run. However, certain advantages of the high-dike systems must be recognized, such as their protection of built up areas and farmers’ ready access to the stable market for rice.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Hellegers, Petra, Promotor
  • van Halsema, Gerardo, Co-promotor
  • Ludwig, Fulco, Co-promotor
Award date29 Nov 2018
Place of PublicationWageningen
Publisher
Print ISBNs9789463435321
DOIs
Publication statusPublished - 2018

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