Author(s): Sameh A. Kantoush; Binh Quang Nguyen; Doan Van Binh; Ngoc Duong Vo; Mohamed Saber; Tetsuya Sumi

Linked Author(s): Mohamed Saber, Tetsuya Sumi

Keywords: Morphological changes; Hydrodynamics; Field survey; Numerical simulations; Vu Gia Thu Bon River basin

Abstract: The Vu Gia Thu Bon (VGTB) River basin plays a vital role in water resources in the central region of Vietnam. However, over the recent decades, dam construction and sand mining have increasingly affected the sediment budget, morphological changes, and hydrodynamics. Therefore, assessing the impact of anthropogenic activities on sediment budget and riverbed elevation can provide scientific insight to understand the morphological changes and hydrodynamics of the VGTB River basin. This study assessed the morphological changes using data from four detailed bathymetric surveys in 2010,2015,2018, and 2021, combined with results from numerical simulations. The field survey in March 2021 was conducted at 71 crosssections along 240 km of VGTB Rivers based on installing the ADCP. We also establish a complete hydrosediment- morphodynamics model and ensure the accuracy of the VGTB River basin. The model was calibrated and validated at hydrological stations along the river system in 2019,2020, and 2021. The simulation results of suspended sediment concentration also have good performance compared with data from turbidimeter, GoogleEarth Engine, and riverbed elevation changes from 2018 to 2021. The total riverbed incision volume during 2010–2021 was -63.30 million cubic meters (Mm3), on average -5.30 Mm3/yr. Sand mining had the most significant influence on the intensified riverbed incision in the study area. The percentage reductions due to sand mining and upstream dams obtained from our empirical formula were 69.7%, and 30.3%, respectively.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1317-cd

Year: 2023