A three-dimensional stratigraphic model of the Mississippi River Delta, USA: implications for river deltaic hydrogeology

  • PDF / 9,992,842 Bytes
  • 18 Pages / 595.276 x 790.866 pts Page_size
  • 32 Downloads / 245 Views

DOWNLOAD

REPORT


REPORT

A three-dimensional stratigraphic model of the Mississippi River Delta, USA: implications for river deltaic hydrogeology An Li 1 & Frank T.-C. Tsai 2

&

Brendan T. Yuill 3 & Chenliang Wu 4

Received: 1 January 2020 / Accepted: 31 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract A three-dimensional stratigraphic model was constructed of the upper 50 m of the Mississippi River Delta, southeastern USA. The model is used to understand hydrogeological connections among the Mississippi River, adjacent interdistributary bays and groundwater systems, and to understand how stratigraphic settings affect potential anthropically induced subsidence and erosion in the region. This study uses 619 geotechnical borings throughout the area along with the multiple-indicator natural neighbor (MINN) interpolation method to construct the model. Based on available data, the study focused on the Mississippi River reach from Head of Passes (river mouth) to Jesuit Bend (108 km upstream), covering an area of approximately 1,800 km2 and ranging in elevation from 3 to −46 m. The model shows typical basal coarse-grained sand bodies overlain by 10-m-thick blanket clay, which is interbedded frequently with silty and sandy sediments and occasionally with peat and organic clay. Sands are most abundant between elevations −10 and −35 m. The Mississippi River main channel incises the underlying sands, thereby providing pathways for river–groundwater exchange. Increased hydrologic loads may propagate along the flow paths potentially giving rise to high pore-water pressure and a resultant increase in land subsidence and thus local erosion of natural and local floodcontrol levees. This method of analysis may apply to other deltaic regions similarly subject to anthropically accelerated subsidence and erosion. Keywords Numerical modeling . Coastal aquifers . Stratigraphy . Indicator interpolation . USA

Introduction

* Frank T.-C. Tsai [email protected] An Li [email protected] Brendan T. Yuill [email protected] Chenliang Wu [email protected] 1

Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803, USA

2

Department of Civil and Environmental Engineering, Louisiana State University, 3255 Patrick F. Taylor Hall, Baton Rouge, LA 70803, USA

3

The Water Institute of the Gulf, 1110 River Road, Suite 200, Baton Rouge, LA 70802, USA

4

Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX 77005, USA

The Mississippi River Deltaic Plain (MRDP) in Louisiana (USA) has a complicated hydrodynamic, geomorphic and stratigraphic setting, being composed of multiple delta lobes and formed under the influences of fluvial, deltaic and marine processes (Bentley et al. 2016; Meselhe et al. 2012; Roberts 1997). Under wholly natural conditions, the lower Mississippi River periodically abandoned its main channel and occupied a shorter, higher-gradient path to the Gulf of Mexico. This process gave rise to new deltas and sublobes that provided sediments to the

Data Loading...