Field methods for measuring hydraulic properties of peat deposits

• Published in: Hydrological processes 2006-11, Vol.20 (17), p.3635-3649
• Main Authors: Hogan, J. M., van der Kamp, G., Barbour, S. L., Schmidt, R.
• Format: Article
• Language: English
• Subjects: drainage tests; Earth sciences; Earth, ocean, space; Exact sciences and technology; field methods; hydraulic conductivity; Hydrology. Hydrogeology; peat; pumping tests; storativity
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.6379

New field techniques were developed and tested to evaluate peat storativity and hydraulic conductivity in a Boreal fen. Enclosed drainage tests and pumping tests were successfully completed in the thawed peat above an impermeable frozen layer and then repeated when the peat was fully thawed. A loading test experiment constrained values of vertical hydraulic conductivity within an order of magnitude for the peat below a depth of 2 m. An inherent advantage of these tests is that volumes of undisturbed peat on the scale of cubic metres may be characterized. Storativity of the fen peat as determined by enclosed drainage tests ranged from about 1·0 at the peat surface to 0·35 at a water table depth of 0·15 m. Laboratory drainage tests of peat cores gave similar, but widely scattered results. Hydraulic conductivity near the surface was as high as 9·0 × 10−3 ms−1 determined with pumping tests and in the range of 10−6 to 10−5 ms−1 below a depth of 2 m, estimated with the loading test. Slug tests gave similar results. Pumping tests, enclosed storativity tests and loading tests are practical large‐scale field tests for determining peat properties. Copyright © 2006 Crown in the right of Canada, and John Wiley & Sons, Ltd.