Paleo-Dendrochronological "Tree-Ring" Hyrdoclimatic Reconstructions for Northern and Southern California River Basins

Background

Tree-ring chronologies allow assessment of hydrologic variability over centuries to millennia, gives historic context for assessing recent droughts, and can be used in climate change research. Tree-ring based reconstructions of annual streamflow and precipitation provide a way to evaluate the observed record of streamflow and precipitation in the context of past centuries and reveal cyclic behavior that may not be detectable in the shorter observed records.

In all reconstructions, longer droughts (consecutive years below the observed record average) have occurred over the past centuries, in some cases double the length of the longest period drought in the observed record. In southern California, a number of the reconstructions indicate that the 2012-2016 drought was the worst 5-year drought in the past six centuries.

Northern California Tree Ring Study

For this study, 16 new tree-ring reconstructions of streamflow and precipitation for use in water-resources planning and operation are provided for the Klamath Basin and Sacramento and San Joaquin Basins. Analysis of droughts in the reconstructions for the three basins indicates the 1920s-30s and 1990s contained periods of drought notably severe in the long-term (centuries to millennia) context. However, the observed record does not contain the driest multi-decadal (50-yr) periods, and in the case of Klamath and San Joaquin, does not include the longest run of drought years.

Southern California Tree Ring Study

For this project, six southern California records were reconstructed: four for total water year precipitation (Ojai, Lake Arrowhead, San Gabriel Dam, and Cuyamaca) and two for water year streamflow (Arroyo Seco and Santa Ana River), along with a reconstruction of Kern River streamflow in the southern Sierra Nevada. In addition, a reconstruction for Colorado River flow at Lees Ferry was updated. One of the most notable findings in this assessment is that, over the 20th and 21st centuries, southern California precipitation and streamflow, along with Kern River streamflow, have been more variable with correspondingly less year-to-year persistence, than over the past six centuries.

Organization

California Department of Water Resources

DWR manages California's water resources, systems, and infrastructure, including the State Water Project (SWP), in a responsible, sustainable way.

Guidebook - Using Tree-Ring Records for...PDF Popular
The purpose of this guidebook is to introduce water resource managers to...
Explore
- Preview
- Download
Southern California Nested ReconstructionsCSV
Nested reconstructions of full natural flow or precipitation for Southern...
Explore
- Preview
- Download
Northern California Nested ReconstructionsCSV Popular
Reconstruction of streamflow and/or precipitation records in the Klamath, San...
Explore
- Preview
- Download
Northern California Ring-Width SeriesZIP Popular
Measured ring-width series (.rwl files) for all chronologies used in the...
Explore
- More information
- Download
Southern California Sup-period Reconstruction...ZIP
Chronologies Table Listing of site chronologies for sites collected under...
Explore
- More information
- Download
Northern California Tree Ring Study (Meko et al. 2014)PDF Popular
This is a draft final report for “Klamath/San Joaquin/Sacramento...
Explore
- Preview
- Download
Southern California Tree-Ring Study (Meko et al. 2017)PDF Popular
The goal of this project was to develop tree-ring based reconstructions of...
Explore
- Preview
- Download

Additional Info

Field	Value
Contact Name	Climate Change Program
Contact Email	[email protected]
Frequency	Other
Public Access Level	Public
Temporal Coverage	Southern California: 1116 - 2016 Northern California: 900 - 2012
Spatial Coverage
Last Updated	August 10, 2018, 17:28 (UTC)