Nguyen Binh Quang, Kantoush Sameh A, Van Binh Doan, Sumi Tetsuya
Water Resource Center, Disaster Prevention Research Institute (DPRI), Kyoto University, Kyoto, 611-0011, Japan.
The University of Danang - University of Science and Technology, 54 Nguyen Luong Bang, Danang, Viet Nam.
Heliyon. 2024 May 28;10(11):e31476. doi: 10.1016/j.heliyon.2024.e31476. eCollection 2024 Jun 15.
The Vu Gia Thu Bon (VGTB) River basin is critical for regional development and prosperity in water resources. However, human interventions (e.g., dam construction and sand mining) have significantly affected this basin's sediment budget and morphological alterations over recent decades. Such humane actions drive an imbalance in water resources in the basin from upstream to downstream. Therefore, this study investigated spatiotemporal changes in sediment budget and morphology alterations using long-term data and bathymetric surveys; from these data, dams and sand mining contributions were quantified and differentiated. Based on field survey data and interviews, we estimated the sand-mining volume by incorporating reported and a newly proposed empirical formula. The results show that the total riverbed incision volume from 2010 to 2021 was 63.30 Mm, with an incision rate of 0.14 m/yr. The officially reported sand-mining rate was 1.12 Mm/yr, while the newly proposed empirical formula estimated 4.4 Mm/yr. According to the developed empirical formula, the percentage reductions in the sediment budget due to sand mining and upstream dams were 69.7 % and 30.3 %, respectively, according to reports, and 17.8 % and 82.2 %. The statistical method was thus likely too conservative compared to the developed empirical formula. We found that the natural sediment supplies sourced from upstream were insufficient to compensate for the mined bed material. Therefore, our combination of different datasets permitted the assessment of future geomorphological developments within the VGTB River basin under the ongoing sediment deficits. The results of this study provide valuable insights into the impacts of human interventions, specifically sand mining, on the sediment budget, morphological alterations, and riverbed incision. The developed assessment forms the foundation for developing and expanding the region's water/sediment resource management strategies.
武嘉-秋盆（VGTB）河流域对区域水资源开发和繁荣至关重要。然而，近几十年来，人类活动（如大坝建设和采砂）显著影响了该流域的泥沙收支和形态变化。这些人类活动导致流域内上下游水资源失衡。因此，本研究利用长期数据和水深测量调查了泥沙收支和形态变化的时空变化；通过这些数据，对大坝和采砂的影响进行了量化和区分。基于实地调查数据和访谈，我们通过结合报告数据和新提出的经验公式估算了采砂量。结果表明，2010年至2021年河床总下切量为6330万立方米，下切速率为0.14米/年。官方报告的采砂速率为112万立方米/年，而新提出的经验公式估算为440万立方米/年。根据所建立的经验公式，报告显示，由于采砂和上游大坝导致的泥沙收支减少百分比分别为69.7%和30.3%，而实际分别为17.8%和82.2%。因此，与所建立的经验公式相比，统计方法可能过于保守。我们发现，上游的天然泥沙补给不足以补偿开采的河床物质。因此，我们结合不同数据集能够评估在持续泥沙亏缺情况下VGTB河流域未来的地貌发展。本研究结果为人类活动，特别是采砂，对泥沙收支、形态变化和河床下切的影响提供了有价值的见解。所建立的评估方法为制定和扩展该地区的水/沙资源管理策略奠定了基础。
