Monitoring Coastline Change in the Red River Delta Using Remotely Sensed Data

Abstract

This study focuses on the use of remotely sensed data for monitoring coastline changes in the Red

Coastal morphological changes in the Red River Delta under increasing natural and anthropic stresses

“…The most frequently cited natural factors include rising sea level (RSL) and more active tropical cyclones in terms of strength and frequency (Fan and Liu 2008;and references therein). Long-term tidal gauged data show the mean RSL rate of 2.24 mm year −1 over the period 1950s-1990s in the RRD, a few higher than the contemporary global average rate of 1.8 mm year −1 (Thanh et al 2005;Thao et al 2013;and references therein). However, the RSL has been overwhelmingly compensated for by rapid deposition at the active distributary mouths and their adjacent coasts in the RRD, producing fast coastal progradation instead of erosion (Figs.…”

“…3), and the reason for such a magnificent morphological change was not well understood. In the sub-region C, coastal erosion occurred persistently from 1935 to 1995, but the erosion magnitude was much lower than that before 1935 (Pruszak et al 2002;Duc et al 2012;Thao et al 2013). The occurrence of severe erosion along the Hai Hau coast in the early 20th century could be ascribed to the abandon of a major distributary debouched into the sea through the Ha Lan river course or nearby (Duc et al 2012).…”

“…Coastline comparison studies may involve using nautical charts, topographical maps, and satellite images, adding further complexity to coastline selection. For example, coastline identifications on satellite images were usually put at the foot of erosion cliffs or sea dikes (near the MHW-coastline) along beach sectors, and at the mangrove forest front boundary (near the MSL-coastline) along muddy coast sectors in the RRD (Dien et al 2003;Hoan et al 2010;Thao et al 2013). This inconsistent coastline identification makes it difficult to do large-scale coastal evolution comparisons.…”

“…Different coastal sectors have diverse responses to the change in sediment flux into the sea through different distributaries and other drivers. In general, most RRD coasts have been observed to undergo net progradation in terms of the vegetation line or high-water line on the accretion muddy flats in the past decades, but Hai Hau coast has been reported to exhibit persistent erosion at least since the 1930s (Imamura and To 1997;Dien et al 2003;Thao et al 2013). Coastal erosion can result from distributary channel shifting, longshore current enhancement, mangrove destruction, and sediment deficit (Pruszak et al 2002;Dien et al 2003;Thanh et al 2004;Duc et al 2007Duc et al , 2012Mai et al 2009;Hoan et al 2010;Thao et al 2013).…”

“…In general, most RRD coasts have been observed to undergo net progradation in terms of the vegetation line or high-water line on the accretion muddy flats in the past decades, but Hai Hau coast has been reported to exhibit persistent erosion at least since the 1930s (Imamura and To 1997;Dien et al 2003;Thao et al 2013). Coastal erosion can result from distributary channel shifting, longshore current enhancement, mangrove destruction, and sediment deficit (Pruszak et al 2002;Dien et al 2003;Thanh et al 2004;Duc et al 2007Duc et al , 2012Mai et al 2009;Hoan et al 2010;Thao et al 2013). In the northern RRD, coastline prograding rates were not observed to change significantly after the completion of Hoa Binh Dam (HBD) in 1988, which has been blamed for the sharp drop in yearly suspended sediment flux at Son Tay station near Hanoi from 119 Mt year −1 (1960)(1961)(1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979) to 46 Mt year −1 (1989-2010) (Vinh et al 2014).…”