The impact of sand mining on the bed morphology of the Tien River, Mekong Delta, Vietnam

Abstract

Sand mining activities in the Mekong Delta river have caused localized erosion holes, altering the once stable flow patterns. Additionally, mining conducted too close to the riverbanks has resulted in bank instability and serious erosion issues. This study aims to evaluate the impact of sand mining on the riverbed changes, particularly the working operations of 26 sand pits along the upper reaches of the Tien River from Tan Chau to My Thuan. The results indicate that sand mining primarily affects the immediate vicinity of the mining areas, leading to heightened scouring levels and causing the mined areas in the floodplain to not fully regenerate within a year following extraction. As a result of sand mining activities, the riverbed experiences increased erosion in comparison to periods with no mining operations. The increased erosion is simulated in two sections of the Tien River, namely the Tan Chau – Hong Ngu and the segment of Tien River passing through the Gieng islet, where the highest additional erosion rates are recorded at 1.2 m/yr and 1.21 m/yr, respectively, compared to the scenario without sand mining. The simulation results also indicate that accretion from the mining sites almost returns to its original state in the segment of the Tien River passing through Sa Dec. However, the recovery of other mining sites in lower areas is significantly less. The findings of this study provide important implications for sand mining planning and natural disaster management, especially concerning erosion control measures.