Tran Dat Q, Nguyen Nguyen N T, Huynh Minh V T, Bairagi Subir K, Le Kieu N, Tran Ty V, Durand-Morat Alvaro
Florida Legislative Office of Economic and Demographic Research, Previously School of Public Policy, University of California, Riverside, CA, USA.
Department of Water Resources, College of Environment and Natural Resources, Can Tho University, Can Tho, Viet Nam.
Sci Total Environ. 2024 Jan 15;908:168140. doi: 10.1016/j.scitotenv.2023.168140. Epub 2023 Nov 2.
The Mekong Delta is one of the most productive rice-producing regions in the world, exporting approximately one-fifth of the global rice traded annually. Previous studies note that saltwater intrusion is a serious concern, and the intensity of saltwater intrusion is primarily driven by sea level rise, land subsidence, anthropogenic sediment starvation, and upstream hydro-infrastructure developments. However, these studies often rely on scenario-based approaches instead of an integrated approach to assess the possible impacts of saltwater intrusion. Using an integrated hydrodynamic-statistical-economic model, we investigate how and the extent to which these drivers may impact the saltwater intrusion. We also examine the costs and returns of two popular saltwater intrusion control policies, i.e., hard-engineering structural and soft-land use planning. When comparing the baseline scenarios, the findings indicate that anthropogenic forces lead to a four times greater saltwater intrusion intensity than the climate change-induced sea level rise. The results further reveal a 50 % or less chance that annual saltwater-affected areas would exceed 1.93 million ha for the baseline, but the likelihood is highly likely to be 100 % with a sea level rising of 22 cm. Under the combined effects of sea-level rise, land subsidence, and riverbed incision, our model shows that the probability of annual saltwater-affected areas staying above 2.30 million ha is almost equal to one. This finding implies that a large share of the current rice-planted areas of the Delta could be wiped out of production for at least one season a year. The findings show that a combination of hard and soft policies would be a more sustainable and cost-effective strategy to lower the intensity and risks of saltwater intrusion. Therefore, there is an urgent need for better coordination of governance and investments among regions within the Delta and counties in the whole Mekong River Basin.
湄公河三角洲是世界上水稻产量最高的地区之一，每年出口约占全球贸易水稻总量五分之一的稻米。此前的研究指出，海水入侵是一个严重问题，海水入侵的强度主要受海平面上升、地面沉降、人为造成的泥沙短缺以及上游水利基础设施建设的影响。然而，这些研究往往依赖基于情景的方法，而非综合方法来评估海水入侵可能产生的影响。我们使用一个综合水动力 - 统计 - 经济模型，研究这些驱动因素如何以及在何种程度上可能影响海水入侵。我们还考察了两种常见的海水入侵控制政策的成本与收益，即硬性工程结构措施和软性土地利用规划。在比较基准情景时，研究结果表明，人为因素导致的海水入侵强度比气候变化引起的海平面上升大四倍。结果还进一步显示，基准情景下受海水影响的年度面积超过193万公顷的可能性为50%或更低，但海平面上升22厘米时，这种可能性极有可能达到100%。在海平面上升、地面沉降和河床下切的共同作用下，我们的模型显示，受海水影响的年度面积持续高于230万公顷的概率几乎为1。这一发现意味着，三角洲目前很大一部分稻田面积每年至少会有一季无法进行生产。研究结果表明，软硬政策相结合将是降低海水入侵强度和风险的更可持续且更具成本效益的策略。因此，迫切需要更好地协调三角洲内各区域以及整个湄公河流域各县之间的治理与投资。
