This study examines the effects of upstream reservoir operation and urbanization on flood inundation in the Vu Gia Thu Bon river basin. The alternative reservoir operation strategies corresponding to the flood storage capacity (Vpl) of 10, 20, and 30% of the active storage capacity (Vhi) are evaluated and compared with the prevailing inter-reservoir operation procedure in terms of inundation effects. The results reveal that increasing the Vpl from 10% to 30% of the Vhi reduces the flooded area by 11.8% and lowers the water level at downstream stations from 6% to 30%. The government's procedure is considered safe to supply water, but the inundation duration is longer, resulting in more damage than the scenario of Vpl=20%Vhi. Regarding urbanization, the expansion of newly urbanized areas has resulted in increased flooding in their surrounding areas, with an increase in flood depth of more than 3 meters. Moreover, the new roads have reduced the capacity of flood drainage and caused severe flooding. The water level difference between the two sides of the road can be as high as 2 meters. This research will assist managers in developing and implementing appropriate downstream flood control measures.

Climate change is a complex problem and becoming the leading challenge for humankind in the 21st century. It will affect almost aspects of human well-being. Therefore, assessing climate change impacts on water resources and proposed solutions to respond to climate change is urgent and necessary. This study applied the SWAT model (Soil and Water Assessment Tool) and GIS (Geographic Information System) technique to simulate water flows due to the impact of climate change. The models were applied for Kon -Ha Thanh river catchment, located in Vietnam where is considered as one of the countries most affected by climate change. The SWAT model is calibrated and validated well using daily flow data with the Nash-Sutcliffe and correlation coefficients are 0.77 and 0.88, respectively. Two scenarios from Vietnamese government (RCP 4.5 and RCP 8.5) are used to analyze the variation of stream flow in three periods: 2016-2035, 2045-2065, and 2080-2100. The results show that the flow in Kon -Ha Thanh rivers will vary complicatedly and severely under the impact of climate change. This flow may increase roughly 150.8% in flood season and reduce around 11.8% in dry season. Furthermore, the study also demonstrates that there are the changes in the flood dynamics as well as the hydrological shift of this region. This study presents an operational approach to integrate the results from the impacts of climate change to flood protection measures that would be useful in sustainable planning and devising resilience strategies.Vietnam is considered as one of the countries to be severely affected by climate change (Change, 2001). Over 50 years, annual average temperature has increased by 0.5-0.70C, and annual precipitation Engineering

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This paper proposes to optimise the operation of the A Vuong reservoir using the dynamic programming technique. The A Vuong is a large reservoir in Vietnam serving multiple purposes, including power generation, flood control, and downstream water supply. First, different flood control storage capacities (Vpl) are investigated, and the best one is chosen based on the criteria of power output and the reservoir's ability to fill up after each regulation cycle. That option is for Vpl to be 50, 30, and 10% of the active storage capacity in September, October, and November, respectively. The study also proposes new operating rule curves with various scenarios of different beginning water levels, ranging from 368 m to 380 m. The average lines of the operating rule curves are also suggested for easier and more efficient operation. Recommendations for using this operating rule curve, as well as its advantages compared to the current one, are also discussed. The results show that the proposed operating rule curves provide much better performance compared with the current in terms of increasing the power output, with a 3.1% increase, while also protecting other water uses.

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