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| Titel |
Applying MODFLOW to wet grassland in-field habitats: a casestudy from the Pevensey Levels, UK |
| VerfasserIn |
R. B. Bradford, M. C. Acreman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 7, no. 1 ; Nr. 7, no. 1, S.43-55 |
| Datensatznummer |
250004419
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| Publikation (Nr.) |
 copernicus.org/hess-7-43-2003.pdf |
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| Zusammenfassung |
| Historical drainage improvements have created complex hydrological regimes in
many low-lying, wet coastal grassland areas. The manipulation of ditch water levels is a
common management technique to maintain important in-stream and in-field habitats in such
areas. However, in wet grasslands with low soil conductivities the water table in the
centre of each field is not closely coupled to variations in ditch stage. Consequently
rainfall and evaporation have a greater influence on the depth to water table and water
table fluctuations within each field. In-field micro-topographic variations also lead
to subtle variations in the hydrological regime and depth to water table that create a
mosaic of different wetness conditions and habitats. The depth, duration, timing and
frequency of flooding from accumulated rainfall, surface water and standing groundwater
also influence the availability of suitable in-field habitats. Land drainage models are
often used for studies of wet grasslands, but tend to be more complex and require more
field variables than saturated zone models. This paper applies a 3D groundwater flow
model, MODFLOW, to simulate groundwater levels within a single field in a wet coastal
grassland underlain by a low permeability sequence and located in the central part of
Pevensey Levels, Sussex, UK. At this scale, the influence of vertical leakage and
regional groundwater flow within the deeper, more permeable part of the sequence is
likely to be small. Whilst available data were not sufficient to attempt a full
calibration, it was found that the sequence could be represented as a single, unconfined
sequence having uniform hydraulic properties. The model also confirmed that evaporation
and rainfall are the dominant components of the water balance. Provided certain
information requirements are met, a distributed groundwater model, such as MODFLOW,
can benefit situations where greater hydrological detail in space and time is required
to represent complex and subtle changes influencing the in-field habitats in wet
grasslands with low permeability soils.
Keywords: wetlands, hydrology,groundwater, MODFLOW |
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