Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model
A new high-performance numerical model (Frehg) is developed to simulate water flow in shallow coastal wetlands. Frehg solves the 2D depth-integrated, hydrostatic, Navier–Stokes equations (i.e., shallow-water equations) in the surface domain and the 3D variably-saturated Richards equation in the subs...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-03-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/13/7/902 |
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| author | Zhi Li Ben R. Hodges |
| author_facet | Zhi Li Ben R. Hodges |
| author_sort | Zhi Li |
| collection | DOAJ |
| description | A new high-performance numerical model (Frehg) is developed to simulate water flow in shallow coastal wetlands. Frehg solves the 2D depth-integrated, hydrostatic, Navier–Stokes equations (i.e., shallow-water equations) in the surface domain and the 3D variably-saturated Richards equation in the subsurface domain. The two domains are asynchronously coupled to model surface-subsurface exchange. The Frehg model is applied to evaluate model sensitivity to a variety of simplifications that are commonly adopted for shallow wetland models, especially the use of the diffusive wave approximation in place of the traditional Saint-Venant equations for surface flow. The results suggest that a dynamic model for momentum is preferred over diffusive wave model for shallow coastal wetlands and marshes because the latter fails to capture flow unsteadiness. Under the combined effects of evaporation and wetting/drying, using diffusive wave model leads to discrepancies in modeled surface-subsurface exchange flux in the intertidal zone where strong exchange processes occur. It indicates shallow wetland models should be built with (i) dynamic surface flow equations that capture the timing of inundation, (ii) complex topographic features that render accurate spatial extent of inundation, and (iii) variably-saturated subsurface flow solver that is capable of modeling moisture change in the subsurface due to evaporation and infiltration. |
| first_indexed | 2024-03-10T12:52:55Z |
| format | Article |
| id | doaj.art-188355144fe04a66bf03c3002d2583e8 |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-10T12:52:55Z |
| publishDate | 2021-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-188355144fe04a66bf03c3002d2583e82023-11-21T12:08:19ZengMDPI AGWater2073-44412021-03-0113790210.3390/w13070902Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater ModelZhi Li0Ben R. Hodges1Energy Geosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USACenter for Water and the Environment, The University of Texas at Austin, Austin, TX 78712, USAA new high-performance numerical model (Frehg) is developed to simulate water flow in shallow coastal wetlands. Frehg solves the 2D depth-integrated, hydrostatic, Navier–Stokes equations (i.e., shallow-water equations) in the surface domain and the 3D variably-saturated Richards equation in the subsurface domain. The two domains are asynchronously coupled to model surface-subsurface exchange. The Frehg model is applied to evaluate model sensitivity to a variety of simplifications that are commonly adopted for shallow wetland models, especially the use of the diffusive wave approximation in place of the traditional Saint-Venant equations for surface flow. The results suggest that a dynamic model for momentum is preferred over diffusive wave model for shallow coastal wetlands and marshes because the latter fails to capture flow unsteadiness. Under the combined effects of evaporation and wetting/drying, using diffusive wave model leads to discrepancies in modeled surface-subsurface exchange flux in the intertidal zone where strong exchange processes occur. It indicates shallow wetland models should be built with (i) dynamic surface flow equations that capture the timing of inundation, (ii) complex topographic features that render accurate spatial extent of inundation, and (iii) variably-saturated subsurface flow solver that is capable of modeling moisture change in the subsurface due to evaporation and infiltration.https://www.mdpi.com/2073-4441/13/7/902coupled surface-subsurface modelshallow coastal wetlandwetting/dryingdiffusive wave approximationevaporation |
| spellingShingle | Zhi Li Ben R. Hodges Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model Water coupled surface-subsurface model shallow coastal wetland wetting/drying diffusive wave approximation evaporation |
| title | Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model |
| title_full | Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model |
| title_fullStr | Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model |
| title_full_unstemmed | Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model |
| title_short | Revisiting Surface-Subsurface Exchange at Intertidal Zone with a Coupled 2D Hydrodynamic and 3D Variably-Saturated Groundwater Model |
| title_sort | revisiting surface subsurface exchange at intertidal zone with a coupled 2d hydrodynamic and 3d variably saturated groundwater model |
| topic | coupled surface-subsurface model shallow coastal wetland wetting/drying diffusive wave approximation evaporation |
| url | https://www.mdpi.com/2073-4441/13/7/902 |
| work_keys_str_mv | AT zhili revisitingsurfacesubsurfaceexchangeatintertidalzonewithacoupled2dhydrodynamicand3dvariablysaturatedgroundwatermodel AT benrhodges revisitingsurfacesubsurfaceexchangeatintertidalzonewithacoupled2dhydrodynamicand3dvariablysaturatedgroundwatermodel |