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%.

中文翻译：

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人类活动和全球变化对越南湄公河三角洲天河未来形态动力学的影响

越南湄公河三角洲内的流体和形态动力学过程受到人类活动的严重影响，进而影响了数百万人的生计。可能影响三角洲未来发展的主要驱动因素是水电开发和采砂等当地压力因素，以及气候变化和相对海平面上升等全球挑战。在这项研究中，开发了一个流体形态动力学模型，该模型侧重于 Tien 河的一段，并嵌套在一个经过良好校准的三角洲流体动力学模型中。开发了多种情景，以评估不同驱动因素对河流形态动力学的预计影响。对基线情景（2000-2010 年）和未来时期（2050-2060 年）的一组合理情景进行了模拟。基线情景的结果表明，在当前条件下，天河已经受到严重侵蚀。在未来一段时间内，水电开发对当地侵蚀和沉积预算的影响最大，从而放大了侵蚀过程，其次是采砂活动增加和与气候变化相关的流量变化。结果还表明，相对海平面上升对该河段的局部形态动力学影响很小，而完全禁止采砂活动减缓了侵蚀趋势。未来，一个不利的驱动因素组合可能会使局部侵蚀和沉积之间的不平衡增加高达 89%，而床层可能会额外切割 146%。