Department of Water Resources Engineering, Chulalongkorn University, Bangkok 10330, Thailand; WISE Research Unit, Chulalongkorn University, Bangkok 10330, Thailand.
Department of Water Resources Engineering, Chulalongkorn University, Bangkok 10330, Thailand; WISE Research Unit, Chulalongkorn University, Bangkok 10330, Thailand.
Sci Total Environ. 2021 May 15;769:145253. doi: 10.1016/j.scitotenv.2021.145253. Epub 2021 Jan 20.
Deltas are inherently low-lying structures and thus subject to large threats due to sea level rise, erosion and other coastal processes. The shorelines in many deltas around the world are now retreating and most cases appear to result from a decreasing sediment supply as a consequence of upstream dam construction. We present here results of an investigation of riverine sediment fluxes, coastal retreat, and coastal sediment accumulation in the Chao Phraya River and Delta (Thailand). This deltaic shoreline has one of the highest rates of shoreline retreat in the world. Surprisingly, our results show that in spite of the construction of two large storage dams, one on the Ping River (Bhumibol Dam, 1964) and the other on the Nan River (Sirikit Dam, 1972) that merge to form the Chao Phraya, sediment accumulation in the delta was actually higher over the last several decades than prior to dam construction. The recent higher rates of sediment accumulation, based on Pb dating, appear to be the result of increased sediment supply in the lower reaches of the river relating to expansion of aquaculture and other activities in the delta beginning in the 1970s. We also show that mangrove removal, in order to further develop shrimp farming, charcoal production, and other pursuits, was not responsible for most of the shoreline erosion. Rather, subsidence, mainly induced by groundwater withdrawal, together with worldwide sea level rise appears to be the main factor affecting the very rapid shoreline retreat of the Chao Phraya Delta.
三角洲地势低洼，因此容易受到海平面上升、侵蚀和其他海岸过程的威胁。世界上许多三角洲的海岸线现在正在后退，大多数情况似乎是由于上游大坝建设导致泥沙供应减少所致。我们在此介绍了对湄公河及其三角洲（泰国）河流泥沙通量、海岸后退和海岸泥沙堆积的研究结果。这个三角洲的海岸线是世界上后退速度最快的海岸线之一。令人惊讶的是，我们的研究结果表明，尽管修建了两座大型水库大坝，一座位于萍河（Bhumibol 大坝，1964 年），另一座位于楠河（诗丽吉大坝，1972 年），这两座大坝合并形成了湄公河，但在过去几十年里，三角洲的泥沙堆积实际上比大坝建设前更高。最近基于 Pb 测年的更高的泥沙堆积率似乎是由于三角洲下游的水产养殖和其他活动的扩张导致泥沙供应增加所致，这些活动始于 20 世纪 70 年代。我们还表明，为了进一步发展虾养殖、木炭生产和其他活动而清除红树林并不是导致大部分海岸线侵蚀的原因。相反，主要由地下水开采引起的地面沉降以及全球海平面上升似乎是影响湄公河三角洲快速后退的主要因素。
