Title: Simulating seawater intrusion in a complex coastal karst aquifer using an improved variable-density flow and solute transport–conduit flow process model

Abstract

VDFST-CFP (variable-density flow and solute transport–conduit flow process) is a density-dependent discrete-continuum numerical model for simulating seawater intrusion in a dual-permeability coastal karst aquifer. A previous study (Xu and Hu 2017) simulates variable-density flow only in a single conduit, and studies the parameter sensitivities only in the horizontal case (2D domain as horizontal section) by the VDFST-CFP model. This paper focuses on the density-dependent vertical case (2D domain as vertical section) with two major improvements: 1) when implementing double-conduit networks in the domain, simulated intruded plumes in the porous medium are extended in the double-conduit scenario, compared to the single-conduit system; 2) by quantifying micro-textures on the conduit wall by the Goudar-Sonnad equation and considering macro-structures as local head loss. Sensitivity analysis shows that medium hydraulic conductivity, conduit diameter and effective porosity are important parameters for simulating seawater intrusion in the discrete-continuum system. On the other hand, rougher micro-structures and additional macro-structure components on the conduit wall would reduce the distance of seawater intrusion to the conduit system, but, rarely affect salinity distribution in the matrix. Compared to the equivalent mean roughness height, the new method (with more detailed description of structure) simulates seawater intrusion slightly landward in the conduitmore » system. Here, the macro-structure measured by local head loss is more reasonable but needs further study on conduit flow. Xu and Hu (2017) Development of a discrete-continuum VDFST-CFP numerical model for simulating seawater intrusion to a coastal karst aquifer with a conduit system.« less

Authors:

Xu, Zhongyuan ^[1]; Hu, Bill X. ^[2]; Xu, Zexuan ^[3]; Wu, Xiujie ^[4]

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+ Show Author Affiliations

1. Univ. of Delaware, Newark, DE (United States); Chengdu Univ. of Technology, Chengdu (China)
2. China Univ. of Geosciences (Beijing), Beijing (People's Republic of China); The Jinan Univ., Guangzhou (People's Republic of China)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
4. Chengdu Univ. of Technology, Chengdu (China)

Publication Date:

Wed Jan 02 00:00:00 EST 2019

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1572016

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Hydrogeology Journal

Additional Journal Information:

Journal Volume: 27; Journal Issue: 4; Journal ID: ISSN 1431-2174

Publisher:

Springer

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Karst; Numerical modeling; Seawater intrusion; VDFST-CFP