| Popis: |
The sediment regime of the Red River system has changed since dams and reservoirs were implemented, with implications for river processes downstream. We analyzed data for the daily discharge (Q) and suspended particulate matter (SPM) concentrations collected from 1958–2021 at the Son Tay hydrological gauging station, the outlet of the Red River system and entry to the delta. The results showed that the annual sediment load transported by the Red River system decreased significantly, by about 90.4%, over the 64-year study period. From 1958 to 1971, when there were no dams or reservoirs in place, the annual water discharges and sediment loads in the river system were about 115,592×106 m3/yr and 115×106 ton/yr, respectively. From 1971 to 2016, a series of dam-reservoir systems were gradually implemented (Thac Ba (1971), Hoa Binh (1988), Tuyen Quang (2008), Son La (2010), Ban Chat (2013), Huoi Quang (2015), and Lai Chau (2016)). By 2016, the annual sediment load and water discharges in the Red River system had decreased significantly, and were 9×106 ton/yr and 88,709×106 m3/yr, respectively. The data show that the discharge and sediment loads increased slightly from 2016–2021, perhaps reflecting the combined effects of human activities, such as land-use change, deforestation, and population increases. Climate may also have played a role in these increases, with changes in air temperature and increases in rainfall triggering severe soil erosion and large discharges of sediment into the Red River system. |
