New research shows that active forest management (e.g., thinning and prescribed fire) significantly benefits water yield, especially during drought years. University of Nevada scientists found that thinning forests, often done for wildfire reduction, also increases mountain runoff. Thinned forests can provide an 8% to 14% increase in water yield when most needed. This finding offers a strong incentive for managers to expand prescribed burning or mechanical tree removal.
When forests are thinned, less rain and snow are intercepted by canopies, allowing more water to reach the ground. Furthermore, removing large trees reduces overall water demand. While increased water yields were traditionally a secondary benefit of thinning, these new computer models offer a detailed understanding of the complex hydrological processes involved.
The research also considers practicalities. While understory plants that thrive post-thinning, can increase total water demand, the net effect still favors increased runoff. Large-scale flooding risks do not significantly increase with greater water yield from thinned forests.
There are also innovative water market opportunities associated with these findings. For example, the US Forest Service is exploring market incentives for thinning operations, including water supply benefits, and organizations like Blue Forest already leverage increased water yields to secure funding for critical forest-resilience projects (see TWR #254).
Beyond improved municipal and agricultural water supplies, thinner forests offer broader forest management benefits such as healthier aquatic ecosystems and enhanced hydropower plant operations. While large-scale thinning is costly, targeted thinning in dense, high-precipitation watersheds can be cost-effective. This research provides valuable tools for managers, paving the way for more sustainable water resource management in a changing climate.
