Assessing flooding features for reservoir flood prevention in Ca River

Abstract

The Ca River basin, including areas such as Bich Hao, Chin Nam, Phuong Dien, and Phuong My, is frequently affected by serious flooding. This has a significant impact on the lives and economic development of local residents in the downstream area of the Ca River. Therefore, it is necessary to evaluate the characteristics of flood formation, and the impact of factors affecting the formation and development of floods such as rainfall, type of soil, slope, land cover, and drainage capacity. More notably, this is important for operating the flood control system of reservoirs along the river branches. This article uses statistical methods and systematic data analysis on rainfall, water flow, and water levels from measurement stations to analyze the characteristics of flood formation in the Ca River basin. Through this analysis, the article identifies five main weather patterns which cause large floods in the Ca River, including (1) tropical storms or tropical depressions, (2) a combination of tropical storms and cold air, (3) a combination of tropical storms and tropical depressions, (4) the convergence of tropical air with the East-Southeast monsoon, and (5) the combination of cold continental air mass, low-pressure troughs, and low-pressure zones passing through the Central-Southern region. Additionally, the study also analyzes rainfall distribution, characteristics of water flow distribution, and the phase shift of floods in the rivers belonging to the Ca River basin. The results show that the largest floods in the rivers of the Ca River basin usually occur as follows: the upstream of Ca river in August, the Hieu River in September, and the La River in October. Besides, large floods in the middle course of the Ca River usually coincide with the floods in the Hieu River.