A REVIEW OF POTENTIAL IMPACT OF TOTAL SUSPENDED SOLIDS ON SURFACE WATER QUALITY AND WATER USES IN THE VIETNAMESE MEKONG DELTA

Abstract

The Vietnamese Mekong Delta (VMD) is an internationally significant region for agricultural production and biodiversity, yet it faces escalating challenges to its water resources. Total Suspended Solids (TSS) represent a critical water quality parameter within this complex deltaic system, with profound implications for its ecological integrity and socio-economic activities. TSS in the VMD originate from a combination of natural processes, such as riverbank erosion and sediment resuspension and increasingly dominant anthropogenic activities, including intensive agriculture, aquaculture, urban and industrial wastewater discharge, upstream hydropower dam development leading to sediment trapping and localized sand mining. Elevated TSS concentrations and alterations in sediment composition directly degrade water quality by increasing turbidity, reducing light penetration essential for aquatic photosynthesis and acting as a transport mechanism for nutrients and various contaminants, including heavy metals and pesticides. These TSS-induced changes in water quality have substantial adverse consequences for key water uses. Agricultural productivity is affected through impacts on irrigation infrastructure and alterations to soil fertility due to reduced beneficial sediment deposition. Aquaculture operations face challenges related to fish and shrimp health, pond management and overall productivity. The suitability of surface water for domestic supply is compromised, necessitating more complex and costly treatment processes and posing potential health risks. Furthermore, TSS contributes to the degradation of aquatic ecosystem health by altering habitats, affecting biodiversity and disrupting fundamental ecological processes. The cumulative effect of these impacts, particularly the long-term reduction in sediment delivery to the delta, also threatens the VMD's geomorphological stability in the face of land subsidence and sea-level rise. Understanding and effectively managing TSS loads and their sources are therefore paramount for the sustainable development and environmental protection of the VMD.