Hydrologic behavior of a forested mountain soil in coastal British Columbia

• Published in: Water resources research 1978-10, Vol.14 (5), p.935-942
• Main Authors: De Vries, J., Chow, T. L.
• Format: Article
• Language: English
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/WR014i005p00935

Inferences with respect to the hydrologic behavior of a West Coast forested mountain soil are based on measurement of the water potential field during the wetting and drainage phases of simulated rainfall events. The field was measured as a continuous function of time with an array of 13 tensiometers in combination with pressure transducers and a data collection system. Measurements were carried out with the forest floor intact, partly disturbed, and totally removed. Inferences were made by interpreting the water potential fields as ‘fingerprints of hydrologic behavior.’ It was concluded that during a simulated rainfall event, water flow through the profile was partitioned between root channels and the soil matrix which is transversed by the channels. The proportion of the flow conducted by the channels was at its maximum during the non‐steady state phase of the event, decreasing to a minimum as steady state was approached. During the drainage phase of the event the channels did not contribute to downward flow. The process of internal infiltration is discussed. It causes the soil matrix to wet up both from the surface of the H horizon of the forest floor and from the wetted periphery of the root channels. Results indicated that simulated disturbance of the forest floor down to the mineral soil caused a shift in the water flow pathway from the channels to the soil matrix. It was speculated that this shift was due to closure of the channel openings. It was speculated that the flashy response of streams to rainfall events is related to rapid subsurface storm flow through root channels. Also, because water flow through the soil matrix is much slower than that through root channels, it is likely that forest floor disturbance on a watershed‐wide scale would result in an increase in the time lag between the rainfall event and the corresponding streamflow event.