The hydraulic conductivity of peat with respect to scaling, botanical composition, and greenhouse gas transport: Mini-aquifer tests from the Red Lake Peatland, Minnesota
•Mini-aquifer tests using PEST were conducted in the 130,000 ha Red Lake peatland.•The tests indicated unexpectedly high permeability values within two bog landforms.•They also detected anomalous permeability patterns throughout the 940 m3 model domains.•These patterns are best explained by biogenic...
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| Published in: | Journal of hydrology (Amsterdam) 2021-05, Vol.596, p.125686, Article 125686 |
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| Main Authors: | , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | •Mini-aquifer tests using PEST were conducted in the 130,000 ha Red Lake peatland.•The tests indicated unexpectedly high permeability values within two bog landforms.•They also detected anomalous permeability patterns throughout the 940 m3 model domains.•These patterns are best explained by biogenic gas bubbles creating secondary porosity.
Hydraulic conductivity (K) is a key but problematic parameter in groundwater models particularly those that simulate flow in weak, readily deformable media, such as peat deposits. As a result, K represents a critical source of error in models that couple hydrological processes with the carbon balance of peatlands, a globally important source for greenhouse gases. We therefore conducted mini-aquifer tests on two mesoscale bog landforms within the large 1300 km2 Red Lake Peatland of northern Minnesota. These tests offer the dual advantage of determining the fine-scale distribution of K within a large (>900 m3) model domain. In addition, the stress created by a 24 h pumping operation should be capable of mobilizing pools of biogenic gases thoughout a deep peat deposit. The pumping results were monitored by 24 to 38 wells in order to calibrate a 3D finite-volume groundwater model with the aid of PEST (Parameter Estimation Analysis). High K values were determined at a Bog Forest (10−5 to 10−6 m s−1) and Bog Lawn (10−3 to 10−4 m s−1) sites, throughout their deep (>4 m) peat profiles. These tests also detected vertically continuous zones of unexpectedly high or low K values in contrast to the horizontal bedding planes and increasing degree of decomposition with depth. The vertical K zones are suggestive of three different modes of bubble transport that either locally dilate or partially block the peat pores. In addition, the tests provided new insights on a conceptual model linking K to the development of all large (>20 km2) forested bog complexes in mid-continental boreal North America. |
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| ISSN: | 0022-1694 1879-2707 |