ABSTRACT: Root zone drainage from a humid forest soil in the west coast of Canada

CGRG Bibliography of Canadian Geomorphology
Search Results

Author :

Date :

Title :

Publication :

Issue :

Page(s) :

Abstract

The hydrologic processes taking place within the root zone control or influence the amounts and rates of water movement to stream channels, the leaching of soluble nutrients, and the effects of forest operations on these parameters. The root zone water balance of a forest soil can be expressed in terms of rainfall, evapotranspiration, surface runoff, change in soil water content, and drainage. A study was conducted to determine and compare the drainages from the root zone of a humid forest soil using two simple and inexpensive methods: (1) Darcy's equation with required data determined in situ; and (2) an unconfined type tension lysimeter system modified to allow manual adjustments of suction on the lysimeter plate according to the tensions in the soil. Root zone drainage from the Jamieson Creek watershed in southwestern British Columbia and within the wetter subzone of the coastal western hemlock biogeoclimatic zone was evaluated. Suction on the lysimeter plate, which had improved hydraulic contact with the soil, was adjusted according to the tension in the surrounding soil. Field-determined soil hydraulic conductivity and hydraulic gradient data were used in the Darcy's equation method. Drainages measured by the two methods were similar with the lysimeter method giving slightly higher values, and drainage amounts during two drying periods agreed well with those estimated from a water balance method. The variations of root zone drainage were closely related to those of rainfall and streamflow of the small surrounding watershed. Human and/or systematic errors may be corrected by making necessary improvements, e.g., utilizing more expensive automatic recording equipment and control devices.

Bibliography of Canadian Geomorphology