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Numerical Simulations of Multi-Species Contaminant Transport in Variably Saturated Aquifers in Coastal Areas. Presenter : Yi-Ming Wei Adviser : Chuen-Fa Ni Date : 2010/10/14. Outline. Introduction Literature review Objectives HYDROGEOCHEM-2D model Test example Future work.
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Numerical Simulations of Multi-Species Contaminant Transport in Variably Saturated Aquifers in Coastal Areas Presenter:Yi-Ming Wei Adviser:Chuen-Fa Ni Date:2010/10/14
Outline • Introduction • Literature review • Objectives • HYDROGEOCHEM-2D model • Test example • Future work
Introduction upper saline plume wave set-up driven circulation (Qw) freshwater discharge tube Reference:C. Robinson, L. Li, D.A. barry (2007) Tide induced circulation (Qt) Density-driven circulation (Qd) fresh groundwater discharge (Qf)
Literature review • Influence of seaward boundary condition on • contaminant transport in unconfined coastal • aquifers. (Q. Zhang et al. , 2001) • Tidal impacts on riparian salinities near • estuaries.(AdrianD. Werner et al. , 2005) • Tidal influence on BTEX biodegradation in • sand coastal aquifers. (D.A Barry et al. , 2009)
Objectives • Combine geochemical and hydrogeological simulated process into HYDROGEOCHEM model • Figure out the impact of recharge and beach slope on solute transport in coastal aquifer.
HYDROGEOCHEM-2D model • Include variably saturated fluid flow, heat transfer, • and reactive chemical transport. • Deal with equilibrium and kinetic reaction in terms • of reaction networks. • Incorporate the effect of precipitation /dissolution • on the change of pore size, hydraulic conductivity, • and diffusion/dispersion.
Flow Equations • Reference:Yeh et al., 1994
Reactive Chemical Transport Equations The rate of mass accumulation The net rate of mass flux due to advection The net mass flux due to dispersion and diffusion The source/sink term corresponding to artificial injection and/or withdrawal The rate of mass production and reduction due to chemical reactions and radioactive decay • Reference:Yeh, 2000
Test Example Pressure head = 85m Pressure head = 84m Variable boundary condition 100 m 400 m Impermeable bottom
Contaminant transport in unsaturated aquifer 1.0 mole/liter ( Br2 ) Pressure head = 84m Pressure head = 85m No rainfall 100 m 400 m Impermeable bottom
Contaminant transport with recharge I= 0.01、0.002m/day Pressure head = 84m Pressure head = 85m 100 m 400 m Impermeable bottom 1.0 mole/liter ( Br2 )
I= 0.01m/day I=0.002m/day
3600 day I= 0.01m/day I=0.002m/day
I= 0.01m/day I=0.002m/day 6000 day
Contaminant transport with pumping well 1.0 mole/liter ( Br2 ) Pressure head = 84m Pressure head = 85m No rainfall 100 m 400 m Impermeable bottom -1.0 m2/day(抽水)
1140 day 3060 day
Contaminant transport with beachslope 1.0 mole/liter ( Br2 ) Beach slope = 0.2、0.3 Pressure head = 85m Pressure head = 84m No rainfall 100 m 400 m Impermeable bottom
Beach slope = 0.2 Beach slope = 0.3
960 day Beach slope = 0.2 Beach slope = 0.3
2022 day Beach slope = 0.2 Beach slope = 0.3
Future work • Sea level oscillations (tidal fluctuation). • Multi-species reactive transport. • Geochemical reaction include precipitation, • adsorption, reaction rate, andbiodegradation. • Aquifer heterogeneity.