Impact of the Hoa Binh dam (Vietnam) on water and sediment budgets in the Red River basin and delta

Abstract

Abstract. The Hoa Binh dam (HBD), located on a tributary of the Red River in Vietnam, has a capacity of 9.45 × 10 9 m 3 and was commissioned in December 1988. Although it is important for flood prevention, electricity production and irrigation in northern Vietnam, the Hoa Binh dam has also highly influenced the suspended sediment distribution in the lower Red River basin, in the delta and in the coastal zone. Its impact was analysed from a 50-year data set of water discharge and suspended sediment concentration , and the distribution of water and sediment across the nine mouths of the delta was simulated using the MIKE11 numerical model before and after the dam settlement. Although water discharge at the delta inlet decreased by only 9 %, the yearly suspended sediment flux dropped, on average, by 61 % at Son Tay near Hanoi (from 119 to 46 × 10 6 t yr −1 ). Along the coast, reduced sedimentation rates are coincident with the lower sediment delivery observed since the impoundment of the Hoa Binh dam. Water regulation has led to decreased water discharge in the wet season (−14 % in the Red River at Son Tay) and increased water discharge in the dry season (+12 % at the same station). The ratios of water and suspended sediment flows, as compared to the total flows in the nine mouths, increased in the northern and southern estuaries and decreased in the central, main Ba Lat mouth. The increasing volume of dredged sediments in the Haiphong harbour is evidence of the silting up of the northern estuary of Cam-Bach Dang. The effect of tidal pumping on enhanced flow occurring in the dry season and resulting from changed water regulation is discussed as a possible cause of the enhanced siltation of the estuary after Hoa Binh dam impoundment.

Recent changes in climate, hydrology and sediment load in the Wadi Abd, Algeria (1970–2010)

“…The sediment flux trapped in regulated basins with reservoirs is higher than 50 % (Vörösmarty et al, 2003). Locally, it can reach more than 60 % after the impoundment of one single dam, like on the Red River (Vinh et al, 2014), and more than 80 % on rivers with many dams (86 % on the Yellow River, Wang et al, 2007; > 95 % on the Ebro River, Durand et al, 2002). Other engineering activities (meander cutoffs, river-training structures, bank revetments, soil erosion controls) also significantly affect sediment fluxes and can participate in the shift from a transport-limited system to a supply-limited system, like on the Missouri-Mississipi River system (Meade and Moody, 2010).…”

Estuarine Turbidity Maxima and Variations of Aggregate Parameters in the Cam-Nam Trieu Estuary, North Vietnam, in Early Wet Season

“…From this period, a large amount of riverine sediment has been trapped in the reservoirs and the sediment flux through the Cam and Bach Dang Rivers to the coastal zones decreased to 6.0 × 10 6 t year −1 , in proportion to 17% the total sediment of the Red-Thai Binh River to the Red river coastal area [40].…”

“…Although the Cam and Bach Dang Rivers belong to the Thai Binh River, they also receive water and sediment from the Red River through the Duong River (see a map of connections within the Red River Delta in Vinh et al [40]. The total river discharge through the Nam Trieu estuary to the coastal zone is about 20 × 10 9 m 3 year −1 , corresponding to 16.5% of the total water discharge from the Red-Thai Binh river system to the Tonkin Gulf [40].…”

“…Based on data from 1960 to 2010, the Red River discharge at Son Tay (near the apex of the Red River delta) varied from year to year over the range 80.5 (in 2010)-160.7 (in 1971) × 10 9 m 3 year −1 , with an average value of 110.0 × 10 9 m 3 year −1 . Water river discharge encompasses strong seasonal variations, with 71-79% of annual total water discharge in the rainy season and only 9.4-18% during the dry season [40].…”

Why and How Do We Study Sediment Transport? Focus on Coastal Zones and Ongoing Methods

“…This process, described in the 1970s [46], is still under study (see [51,142]). This key mechanism of delta geomorphodynamics is very sensitive to changes in flows, and river water regulation induced by dams is enough to move the estuarine turbidity zone and cause the silting up of navigation channels and river ports, as on the Red River [157].…”