Quantification of Water Storage in Fingers Associated with Preferential Flow in Milled Peat Stockpiles

Abstract

The economic value of stockpiled milled peat for fuel energy is dependent on its wet-weight water content when sold. Research into milled peat stockpile rewetting has shown that, while there is surface rewetting (a wet layer), there is also significant through-flow water movement into the center of the stockpile with associated zones (termed fingers) of water storage. A method of quantifying the importance of finger storage was developed using serial digital images obtained in the field. Results showed that the wetted volume within a stockpile was similar regardless of milled peat type ({approx}40%), and that the internal wetting contributed up to 28 times more to final water content than the surface wet layer. Thus surface wet layers have relatively little economic impact when compared with finger storage. Field observation of through-flow indicated that a rivulet flow mechanism in conjunction with stockpile geometry contributes to the development of fingers.