Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips – Part 1: nonuniform infiltration and soil water redistribution
Vegetation buffers like vegetative filter strips (VFSs) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in floodplains often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and i...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-01-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/22/53/2018/hess-22-53-2018.pdf |
| Summary: | Vegetation buffers like vegetative filter strips (VFSs) are often used to
protect water bodies from surface runoff pollution from disturbed areas.
Their typical placement in floodplains often results in the presence of a
seasonal shallow water table (WT) that can decrease soil infiltration and
increase surface pollutant transport during a rainfall-runoff event. Simple
and robust components of hydrological models are needed to analyze the
impacts of WT in the landscape. To simulate VFS infiltration under realistic
rainfall conditions with WT, we propose a generic infiltration solution
(Shallow Water table INfiltration algorithm: SWINGO) based on a combination
of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with new
integral formulae to calculate singular times (time of ponding, shift time,
and time to soil profile saturation). The algorithm was tested successfully
on five distinct soils, both against Richards's numerical solution and
experimental data in terms of infiltration and soil moisture redistribution
predictions, and applied to study the combined effects of varying WT depth,
soil type, and rainfall intensity and duration. The results show the
robustness of the algorithm and its ability to handle various soil hydraulic
functions and initial nonponding conditions under unsteady rainfall. The
effect of a WT on infiltration under ponded conditions was found to be
effectively decoupled from surface infiltration and excess runoff processes
for depths larger than 1.2 to 2 m, being shallower for fine soils and
shorter events. For nonponded initial conditions, the influence of WT depth
also varies with rainfall intensity. Also, we observed that soils with a
marked air entry (bubbling pressure) exhibit a distinct behavior with WT near
the surface. The good performance, robustness, and flexibility of SWINGO
supports its broader use to study WT effects on surface runoff, infiltration,
flooding, transport, ecological, and land use processes. SWINGO is coupled
with an existing VFS model in the companion paper (Lauvernet and
Muñoz-Carpena, 2018), where the potential effects of seasonal or
permanent WTs on VFS sediment and pesticide trapping are studied. |
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| ISSN: | 1027-5606 1607-7938 |