FIELD ESTIMATION OF MACROPORE FUNCTIONING AND SURFACE HYDRAULIC CONDUCTIVITY IN A FEN PEAT

A limitation of existing models of water and solute movement in fen pe ats is that they fail to represent processes in the unsaturated zone. This limitation is largely due to a lack of data on the hydraulic prop erties of unsaturated peat, in particular the relationship between hyd raulic conductivity (K) and pressure head (psi). A tension infiltromet er was used to measure K(psi) of a fen peat in Somerset, England. It w as found that macropores could be important in water and solute moveme nt in this soil type. It was also found that (i) variability of K in t his peat was less than that reported for other peats and mineral soils , and (ii) the K data were better described by a log-normal distributi on than a normal distribution in accord with findings from other peat and mineral soils. Recommendations on improving the understanding of w ater and solute movement in the unsaturated zone of this soil type are made. (C) 1997 by John Wiley & Sons. Ltd.