Laboratory Investigation of Infiltration Processes in Frozen Soil and the Influence of Antecedent Moisture Content and Macroporosity

Abstract

Snowmelt infiltration into frozen soil can recharge soil moisture and groundwater storage. In order to better understand the complex processes involved, the influence of antecedent moisture content and macroporosity on infiltration in frozen soil was investigated. Infiltration experiments on frozen macroporous and non-macroporous soil columns revealed dry macroporous soil can produce infiltration rates reaching 10^3 to 10^4 mm day^-1, 3 to 4 orders of magnitude larger than dry non-macroporous soil. Results suggest rapid infiltration was a result of preferential flow through air-filled macropores. These findings imply significant infiltration is possible at all landscape positions (uplands and depressions) under dry soil conditions. Under wet conditions, regardless of the presence of macropores, infiltration was restricted by the slow thawing rate of ice, producing infiltration rates of a mere 2.8 to 5.0 mm day^-1. Restricted infiltrability will increase surface runoff to local depressions, where deep drainage occurs once the soil thaws.