Sand mining in the Mekong Delta: Extent and compounded impacts

Sand mining has accelerated in recent years primarily due to population increase and rapid urbanization. To meet demand, the rate of sand extraction often exceeds the rate of natural replenishment with serious environmental consequences. In this review paper, the Vietnamese Mekong Delta (VMD), a global hotspot for sand mining with a prolonged history of intensive riverbed extraction, is used as a representative case study to highlight the extent and compounded impacts of this activity. Sand mining budgets from literature present significant discrepancies, with estimates for the entire delta varying from around 8.5 to 42.2 Mm³/yr. These variances can be attributed to the challenges in the actual measurement of mining rates and the deployment of disparate methods across studies. Moreover, the widespread practice of illegal sand mining in the region further exacerbates the mismatch in budget calculations. Consequences of such mining activities manifest as deeply-incised riverbeds leading to riverbank and coastal erosion. Moreover, the massive sediment removal has resulted in river water level reductions, disrupted hydrological connectivity, and diminished floodplain inundation. The augmented backwater effect, a result of riverbed lowering, amplifies saltwater intrusion in dry seasons. While the physical and hydrological impacts have received attention, studies on the ecological and societal ramifications remain sparse. These impacts, further magnified by factors like upstream dams, irrigation infrastructures, excessive groundwater extraction, and sea-level rise (SLR), present a multifaceted challenge. This paper concludes by advocating for the adoption of remote sensing-based approaches for effective mapping of sand mining activities, and implementation of sustainable sand harvesting practices to balance developmental needs with environmental conservation.