Operating Multi-Purpose Reservoirs in the Red River Basin: Hydropower Benefit Optimization in Conditions Ensuring Enough Water for Downstream Irrigation

Abstract

Operational management of multiple reservoirs and hydropower plants in the Red River Basin (RRB) in Vietnam was investigated for optimal benefit of hydropower generation and to ensure the water supply for agricultural and social–economic development downstream during the dry season. This research will investigate the operation of three hydropower reservoirs, including Hoa Binh, Thac Ba, and Tuyen Quang reservoirs. Those reservoirs are managed under the operating Decision No. 740 of the Prime Minister in 2019, which stipulates the dry season and water - enhanced discharge period to supply water for agriculture and ensures that the minimum water level in Hanoi is above 2.2 m, which may lead to lack of water for hydropower plants. To do this, I used the optimization approach to determine the optimal water discharge scenario in these three reservoirs during the enhanced discharge period (irrigation water supply). Based on the optimal scenario, I calculated the amount of saved water which is then compared with the standard discharge scenario under Decision No. 740. This study also found that there is an increasing economic benefit from saved water and hydropower generation during peak hours (after the winter–spring crop). Addtionally, the results demonstrated that the economic value added by the power generation of three reservoirs is about 401.7 billion VND. If compared with using thermal power plants, it saves 858.0 billion VND.