A tale of two droughts: the role of drought in the hydrologic response of a managed coast redwood watershed
| Authors: | Elizabeth Keppeler, Joseph Wagenbrenner |
| Year: | 2019 |
| Type: | Full Proceedings |
| Station: | Pacific Southwest Research Station |
| Source: | 6th Interagency Conference on Research in the Watersheds |
Abstract
In California, projections of intensifying wet-dry extremes and shifts in precipitation seasonality suggest that hydrologic droughts may become more frequent in the coast redwood region. An increase in hydrologic drought frequency may be particularly problematic for aquatic species that rely on flow in headwater streams during the region’s June-October dry season.
We used a 55-year record of precipitation and streamflow to explore the relationship between meteorological drought and hydrologic drought in the Caspar Creek Experimental Watersheds in north coastal California. The 4.24- km2 South Fork (SF) and 4.73-km2 North Fork (NF) watersheds are managed for research and timber production. Originally clearcut and burned prior to 1904, second-cycle selection-harvest occurred on the SF from 1967 to 1973 and partial-clearcutting on the NF from 1985 to 1992.
The only significant trend in annual precipitation and precipitation-adjusted runoff over the period of record was for SF runoff (p=0.02). It is not yet clear whether the decline in SF runoff is a response to forest regrowth, climatic variation, or a combination of both.