Spatial and seasonal variability of sediment accumulation potential through controlled flooding of polders in the Ganges-Brahmaputra-Meghna delta of southwest Bangladesh

Islam, Feroz; Middelkoop, H.; Schot, P.P.; Dekker, Stefan C.; Griffioen, Jasper

doi:10.22541/au.157843099.95556612

Cited by 1 publication

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Following Islam et al (2020) and Lázár et al (2015), we distinguished three flow seasons: the dry season (November to February), pre-monsoon (March to May) and monsoon (June to October). For all flow regions, TR is highest during the pre-monsoon season and lowest during the monsoon season (Islam et al, 2021). Tidal range is generally higher for the rivers in the TDF region than for the rivers in the RDF region of the southwestern delta.…”

Section: Scenario Matrix For Hydro-morphodynamic Modellingmentioning

confidence: 90%

“…Tidal range (TR) and SSC vary spatially for different flow regions and seasons. Islam et al (2021) divided the southwestern delta into three regions based on the flow regime of their rivers: river-dominated flow (RDF), mixed river-tide flow (MF), and tide-dominated flow (TDF) regime in the coastal area. Following Islam et al (2020) and Lázár et al (2015), we distinguished three flow seasons: the dry season (November to February), pre-monsoon (March to May) and monsoon (June to October).…”

Section: Scenario Matrix For Hydro-morphodynamic Modellingmentioning

confidence: 99%

“…Suspended sediment concentration (SSC) in the river is highest during the monsoon and lowest during the dry season for RDF and MF regions. For the TDF region, SSC in the river is highest during the pre-monsoon and lowest during the dry season (Islam et al, 2021). For the scenarios, we used the TR and the SSC that occur within the three flow regime regions during the different seasons as defined by Islam et al (2020Islam et al ( , 2021 (Table 1).…”

Section: Scenario Matrix For Hydro-morphodynamic Modellingmentioning

confidence: 99%

“…The boundary conditions provided by the river channel to which a beel is connected are major, external factors for deposition (e.g., Talchabhadel et al (2017;Islam et al, 2020Islam et al, , 2021. The river flow, flood stage, tidal range, inundation depth of a beel and suspended sediment concentrations in the feeding tidal channels together determine the amount of suspended matter that can enter and settle inside the beel.…”

Section: Introductionmentioning

confidence: 99%

“…Since these external boundary conditions may vary across the southwestern (SW) Ganges-Brahmaputra delta in Bangladesh, these may result in considerable regional variation in potential success of TRM application. Islam et al (2021) explored the applicability of TRM in southwestern Bangladesh for different river flow regimes. The tidal-dominated river zone near the sea in the south and the mixed tidal-river flow regime about 60 km inland were found to be most suitable for raising land level with TRM.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Physical controls and a priori estimation of raising land surface elevation across the southwestern Bangladesh delta using Tidal River Management

Islam

Schot

Dekker

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The Ganges-Brahmaputra-Meghna delta in Bangladesh is one of the largest and most populated deltas in the world and threatened by relative sea level rise (RSLR). Renewed sediment deposition through tidal river management (TRM), a controlled flooding with dike breach, inside the lowest parts of the delta polders (so-called “beels”) can potentially counterbalance RSLR. The potential of TRM application in different beels across southwestern Bangladesh, however, still remains to be determined. We used a 2D morphodynamic model to explore the physical controls of five variables on total sediment deposition inside the beels during TRM: river tidal range (TR), river suspended sediment concentration (SSC), inundation depth (ID), width of the inlet (IW) and surface area of the beel (BA). Non-linear regression models (NLMs) were developed using the results of 2D models to quantify how sediment deposition inside the beels depends on these variables. The NLMs have an average coefficient of determination of 0.74 to 0.77. Application of the NLMs to 234 beels of southwestern Bangladesh indicates that TRM operation in beels located closer to the sea will retain more sediment as a result of decreasing SSC further inland. Beels in the western part retain more sediment because of lower average land surface elevation. Smaller beels have higher potential to raise land surface elevation due to nonlinear increase of sediment deposition per day (SPD) with beel area. Compartmentalization of larger beels may increase their potential to raise land surface elevation. Thus, the length of time of TRM application in cyclic order will need to vary across the delta to counterbalance RSLR, depending on current beel land surface elevation and local TRM sediment accumulation rates. We found that operating TRM only during the monsoon season is sufficient to raise land surface in 96 % and 80 % of all beels by more than 3 and 5 times the yearly RSLR, respectively. Applying TRM only seasonally offers huge advantages as to keeping the land available for agriculture during the rest of the year. The methodology presented here applying regression models based on 2D morphodynamic modeling may be used for the low-lying sinking deltas around the world to provide an a-priori estimation of sediment deposition from controlled flooding to counterbalance RSLR.

show abstract

Section: Scenario Matrix For Hydro-morphodynamic Modellingmentioning

confidence: 90%

Section: Scenario Matrix For Hydro-morphodynamic Modellingmentioning

confidence: 99%