Loading...
Understanding the impact of forest treatments on surface water runoff in a Sierra Nevada watershed
Smith, Katy
Smith, Katy
Citations
Altmetric:
Advisor
Editor
Date
Date Issued
2023
Date Submitted
Keywords
Collections
Research Projects
Organizational Units
Journal Issue
Embargo Expires
Abstract
Snow dominated forests serve as source water supplies to much of the western United States. In recent years, these forests have experienced an increase in both drought and wildfire, which threaten critical water supplies. By reducing forest density, forest treatments offer a promising solution to reducing fuel loads and potentially increasing water yield. However, the amount of fuel load reduction necessary to produce a change in water yield is not well-characterized. The objectives of the current study are: 1) parameterize a distributed, integrated hydrologic model to capture a range of fuel treatment scenarios in a heavily forested experimental basin in the Sierra Nevada (Sagehen Creek basin near Truckee, California, USA), and 2) determine the extent (threshold) of forest treatments necessary to produce significant changes in surface runoff – specifically what extent of forest treatment is necessary to increase the average annual runoff by 25\%. Using the physically-distributed model, MIKE SHE, ten forest treatment scenarios with varying intensity and area of treatment were simulated for a five-year period. Statistical testing showed that significant change for a 99\% confidence interval in runoff occurred for every scenario, and the basin experienced a 25\% or more increase in average annual runoff when treating the basin between 40\%-60\% intensity, or higher. Water yield is highly correlated and dominated by precipitation, however, treatments have a compounding effect over the years and the basin has a more dramatic response to higher treatment intensities. Increasing treatment intensity was more effective at increasing water yield than increasing treatment area. As forest managers implement forest treatments, consideration of the variability in water yield response that could occur is dependent on 1) the degree to which treatments are implemented by either area or intensity, 2) future climate variability including extended periods of drought, and 3) basin storage (groundwater) conditions and how this might buffer disturbance response in the basin.
Associated Publications
Rights
Copyright of the original work is retained by the author.