Hydrologic behaviour of a mountainous watershed

A simplified watershed model has been developed to examine and analyze the high rainfall response of a small, steep, and forested watershed in coastal British Columbia. Hourly data for both rainfall and streamflow are used. Rainfall is measured at five points evenly distributed throughout the watershed. The model is found to perform well and indicates that the hydrologic response of the watershed is reasonably linear, except for intense summer rainstorms under dry soil conditions. The linearity and the rapidity of the watershed response is attributed to the response of the subsurface pipeflow. An analysis of a particular case of soil pipe development shows that the pipeflow system can respond linearly and rapidly to the rainfall input. Key words: watershed modelling, hydrologic response, soil piping.