Hydrologic Analysis of a Steep Forested Watershed Using Spatially Distributed Measurements of Soil Moisture and Soil Infiltration Properties

by
Gregory Charles Loscher

Master of Science, Utah State University, 2006
Major Professor: Dr. David Tarboton
Department: Civil and Environmental Engineering

Full Thesis PDF Document [6MB, 184 pages]

Abstract

Soil volumetric water content (VWC) was measured over a 4 month period in a humid, steep, forested, 17-ha watershed using portable impedance and static water content reflectometer probes. The shallow soil moisture profile pivoted approximately linearly about saturation at the base during wetting and drying cycles. Watershed topography was not found to be a significant factor in VWC distribution. Stream stormflow appeared to result from flow along the soil-bedrock interface on a time scale of hours to days, while baseflow appeared to result from soil matrix drainage on a time scale of weeks to months. VWC measurement sites were analyzed for temporal stability to evaluate potential single site surrogacy for average watershed soil moisture conditions. VWC measurements at one continuously monitored, temporally stable site were used to estimate hourly watershed soil water storage changes. For wet periods, the result compared well with hourly storage changes estimated from a water balance.