Morphodynamics at the Coastal Zone in the Laizhou Bay, Bohai Sea

Abstract

Morphogenetic processes of the Yellow River Delta and the Laizhou Bay, Bohai Sea, China, have to be described by the interrelation of riverine sediment supply, relative sea level change and the effects of wind driven waves and nearshore currents. The research area is regarded a natural laboratory of the development of river dominated coastal zone with interfering natural and anthropogenic forcing factors. As well for the historical hindcast as for future projections of the morphogenetic coastal processes the Dynamic Equilibrium Shore Model ( DESM) can be applied. This model generalizes the standard Bruun rule model and generates Digital Elevation Models ( DEMs) scenarios on decadal to centennial time scales for the geological past and future. The basic concept is a dynamic equilibrium coastal profile evolution in adaption to the sediment budget in a spatially three-dimensional domain. By adding parameters to account for sediment mass contribution from riverine sediment flux, the DESM can be used to explore coastal morphological equilibrium states responding to sediment budget changes for river-dominated coastal zones. For the parameterization historical maps of the southern Bohai Sea have been applied to reconstruct paleo-coastlines for the 19 th century for the comparison with a modern DEM. Gauge measurements provided the data for an estimation of trends in sea level change for the Laizhou Bay on the decadal scale. Modern sea level rise together with reduced riverine sediment supply caused by anthropogenic activities such as damming up-streams may change the depositional environment at the Yellow River Delta and related areas of the Laizhou Bay from river dominated ( progrational) to wave dominated ( regressive) environment. ADDITIONAL INDEX WORDS :Coastal morphodynamics, Laizhou Bay, Dynamic Equilibrium Shore Model; river sediment flux; relative sea level change.

Sediment Flux, Coastal Development, and Industrial Pressure Drive the Historical Vanadium Concentrations in the East China Sea and Two Bays of Shandong

“…41 Between 1953 and 1964, the delta was at the northeast corner of the bay, and vanadium concentrations were elevated and constant within that period owing to southward moving currents and elements. 42 The subsequent vanadium reduction could also be associated with a change in the delta to the north, closer to the Bohai Sea. Here, currents circulate predominantly to the east, removing sediments and other minerals from the study site and reducing the vanadium concentrations.…”

A Tale of Two Deltas: Dam-Induced Hydro-Morphological Evolution of the Volta River Delta (Ghana) and Yellow River Delta (China)

“…Notably, the inter-annual variability of precipitation in the Yellow River Basin has also been reduced since the mid-1980s due to the strong and frequent El Niño Southern Oscillation (ENSO) [5,49]. Furthermore, due to the gradual decrease in sediment supply, the Yellow River Delta has also been shifting from a river-dominated to a wave-dominated delta in recent years [9,26,27]. July to September are the flood season in the Yellow River, with an average river discharge of about 3260.67 m 3 /s, while October to June are the dry season, with an average river discharge of about 724.59 m 3 /s [53].…”

“…A decreasing sediment load resulted in the historical adjustment of the shorelines and areas of both deltas, which further led to their shift from river-dominated to wavedominated deltas [9,[24][25][26][27]. The different shoreline and area evolutions were presumably due to contrasting patterns of hydrological alterations, and the relative strengths of the fluvial and wave forcings of the two deltas.…”

“…Firstly, the Volta River and Yellow River are both heavily regulated by dams, and the sediment supply, frequency and peak discharge of floods have reduced remarkably under dam regulation [19,22,23]. Secondly, both deltas have shifted or are shifting from river-dominated to wave-dominated deltas due to reduced sediment load [9,[24][25][26][27]. Thirdly, both deltas play a critical role in the local economy and ecosystem [19,22].…”

Morphogenetic modelling of coastal and estuarine evolution

“…(3). The DESM model has extended the equilibrium concept developed by Dean (1991) quantitatively to quasi-three dimensions (Deng et al, 2014;Deng et al, 2015;Deng et al, 2016).…”