Effects of Sea Level Rise on Deltaic Coastal Marshlands, Mississippi River Deltaic Plain: ABSTRACT

Abstract. The objective of this paper was to describe the impact of climate change on the Mississippi River flood hazard in the New Orleans area. This city has a unique flood risk management challenge, heavily influenced by climate change, since it faces flood hazards from multiple geographical locations (e.g. Lake Pontchartrain and Mississippi River) and multiple sources (hurricane, river, rainfall). Also the low elevation and significant subsidence rate of the Greater New Orleans area poses a high risk and challenges the water management of this urban area. Its vulnerability to flooding became dramatically apparent during Hurricane Katrina in 2005 with huge economic losses and a large number of casualties. A SOBEK Rural 1DFLOW model was set up to simulate the general hydrodynamics. This model included the two important spillways that are operated during high flow conditions. A weighted multi-criteria calibration procedure was performed to calibrate the model for high flows. Validation for floods in 2011 indicated a reasonable performance for high flows and clearly demonstrated the influence of the spillways. 32 different scenarios were defined which included the relatively large sea level rise and the changing discharge regime that is expected due to climate change. The impact of these scenarios on the water levels near New Orleans were analysed by the hydrodynamic model. Results showed that during high flows New Orleans will not be affected by varying discharge regimes, since the presence of the spillways ensures a constant discharge through the city. In contrary, sea level rise is expected to push water levels upwards. The effect of sea level rise will be noticeable even more than 470 km upstream. Climate change impacts necessitate a more frequent use of the spillways and opening strategies that are based on stages.

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Analysis of the postglacial deposits of the Rhône shelf (golfe du Lion). Implementation to the study of the late Quaternary depositional sequences

BSGF - Earth Sciences Bulletin ◽

10.2113/174.4.401 ◽

2003 ◽

Vol 174 (4) ◽

pp. 401-419 ◽

Cited By ~ 23

Author(s):

Bernard Gensous ◽

Michel Tesson

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Late Quaternary ◽

Sediment Supply ◽

Ocean Dynamics ◽

Outer Shelf ◽

Inner Shelf ◽

Depositional Sequences ◽

Incised Valley ◽

Deltaic Plain

Abstract Postglacial deposits of the Rhône shelf have been studied from high-resolution seismic data and Kullenberg piston cores. They are organised into a set of transgressive units or parasequences backstepping from the outer shelf to the subaerial deltaic plain. On the deltaic plain, they are overlain by the prograding deltaic parasequences deposited at the end of the Holocene sea level rise. At regional scale, given the short time span covered by the late Quaternary deposits, tectonic subsidence has played a minor role and sediment deposition on the Rhône shelf was chiefly controlled by glacio-eustatic sea level changes (120 m between the maximum lowstand and present highstand). Progradational phases correspond to periods of reduced rate of eustatic sea level rise while the flooding surfaces bounding the regressive units form during periods of increasing rate of sea level rise and landward shoreline migration. At local scale, location, geometry, nature of deposits, and lateral variations of the stratigraphic pattern are controlled by the interaction between eustasy and local factors as sediment supply, antecedent morphology and ocean dynamics. Seaward of the Rhône river, terrigenous input was important during deglaciation and transgressive deposits extend continuously from the outer shelf to the inner shelf along the retreating path of the paleo-Rhône river mouth. Laterally, on either side of the Rhône incised valley, because of the reduced sediment supply, parasequences only develop on the outer shelf and inner shelf : the combination of the very low inherited gradient of the mid/outer shelf and a very high rate of sea level rise favoured a very rapid migration of the shoreline from outer to inner shelf. Ocean dynamics has been controlled, as in present time, by the E to SE prevailing waves that are the only ones which can develop on an extended fetch. The westward alongshore drift accounted for the development of parasequences west of the incised valley. The sandy material needed for the construction of the outershelf parasequence was supplied by wave-reworking and westward long-shore drift of deposits from the Rhône delta front and the uppermost forced regressive unit. The decreasing sand content of parasequences from outer shelf to inner shelf results from flattening of the equilibrium river profile that led to a decrease in competence and a change in the character of the sediment caliber (relative increase of suspension load). The underlying Pleistocene depositional sequences comprise both lowstand prograding units, that characterize most of the Mediterranean shelves, and intercalated units which are analogs of the postglacial transgressive deposits here presented.

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Response scenarios for the deltaic plain of the Rhône in the face of an acceleration in the rate of sea-level rise with special attention toSalicornia-type environments

Estuaries ◽

10.1007/bf02695978 ◽

2002 ◽

Vol 25 (3) ◽

pp. 337-358 ◽

Cited By ~ 66

Author(s):

Didier Pont ◽

John W. Day ◽

Philippe Hensel ◽

Evelyne Franquet ◽

Frank Torre ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Deltaic Plain ◽

The Face

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Accounting for DEM Error in Sea Level Rise Assessment within Riverine Regions; Case Study from the Shatt Al-Arab River Region

Environments ◽

10.3390/environments8050046 ◽

2021 ◽

Vol 8 (5) ◽

pp. 46

Author(s):

Ali K. M. Al-Nasrawi ◽

Ameen A. Kadhim ◽

Ashton M. Shortridge ◽

Brian G. Jones

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Mississippi River ◽

Coastal Region ◽

Shuttle Radar Topography Mission ◽

Multiple Regression Model ◽

Propagation Model ◽

River Region ◽

The Impact ◽

Inundation Model

Global elevation datasets such as the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) are the best available terrain data in many parts of the world. Consequently, SRTM is widely used for understanding the risk of coastal inundation due to climate change-induced sea level rise. However, SRTM elevations are prone to error, giving rise to uncertainty in the quality of the inundation projections. This study investigated the error propagation model for the Shatt al-Arab River region (SARR) to understand the impact of DEM error on an inundation model in this sensitive, low-lying coastal region. The analysis involved three stages. First, a multiple regression model, parameterized from the Mississippi River delta region, was used to generate an expected DEM error surface for the SARR. This surface was subtracted from the SRTM DEM for the SARR to adjust it. Second, residuals from this model were simulated for the SARR. Modelled residuals were subtracted from the adjusted SRTM to produce 50 DEM realizations capturing potential elevation variation. Third, the DEM realizations were each used in a geospatial “bathtub” inundation model to estimate flooding area in the region given 1 m of sea level rise. Across all realizations, the area predicted to flood covered about 50% of the entire region, while predicted flooding using the raw SRTM covered only about 28%, indicating substantial underprediction of the affected area when error was not accounted for. This study can be an applicable approach within such environments worldwide.

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