Understanding the anthropogenic development impacts on long-term flow regimes in a tropical river basin, Central Vietnam

The Vu Gia Thu Bon (VGTB) basin constitutes the primary water supply in Central Vietnam. While climate change disturbs stream discharges and affects flood extremes, upstream dam development may intensify or mitigate such impacts. Therefore, this study provides a quantitative evaluation of long-term alterations in the flow regimes of the VGTB rivers from 1977 to 2020 resulting from the impacts of upstream anthropogenic developments. The datasets are divided into two periods, pre-2000 (1977-2000) and post-2000 (2001-2020), using different indices and analytical methods. The analyses show that since 2011, reservoir operations have reduced the maximum and high-flow discharges downstream in excess of climate change and land-use effects. However, due to the impact of water transfer by the Dak Mi 4 hydropower dam from the Vu Gia River to the Thu Bon River through a diversion channel, the minimum and low-flow discharges decreased in the pre-dam period and increased in the post-dam period.

Automated summary

This study quantitatively evaluates the long-term alterations in flow regimes of the Vu Gia Thu Bon rivers in Central Vietnam from 1977 to 2020, caused by upstream anthropogenic developments. The findings show that reservoir operations have reduced maximum and high-flow discharges since 2011. However, the construction of the Dak Mi 4 hydropower dam has led to decreased minimum and low-flow discharges in the pre-dam period and increased discharges in the post-dam period.