Climate Change Projections for USFS Lands
in Oregon and Washington
The purpose of this project is to use existing climate change datasets from the Climate Impacts Group (CIG) to summarize the the projected climate change impacts to United States Forest Service (USFS) lands in Oregon and Washington (Figure 1). Stakeholders in the Forest Service of this region were particularly interested in the variables that are likely to impact freshwater aquatic species, including projected changes in water availability, snowpack, and flood and low flow severities.
click image to enlarge
Figure 1 Map of the study region showing boundaries for Bailey ecosections (left panel), Omernik level III ecoregions (middle panel), and HUC4 basins (right panel). Flow statistics are also summarized over the smaller HUC5 basins (not shown). The light green shading on each map indicates USFS lands.
Methods and Products
Our objective is to summarize climate and hydrologic projections for USFS lands in Oregon and Washington. Since individual national forests may contain numerous distinct ecological regimes and cross hydrologic boundaries, averaging over these has the potential to obscure important climatic changes and confound planning efforts. In order to avoid this pitfall, we chose to provide summaries that follow ecological and hydrologic boundaries, rather than administrative borders.
These summmaries are produced using results from the CIG Columbia Basin Climate Change Scenarios Project (CBCCSP, Hamlet et al., 2010). The CBCCSP dataset consists of an in-depth suite of high-resolution climate projections for the Columbia river basin and coastal drainages in Oregon and Washington. Specifically, the CBCCSP dataset includes a gridded 1/16th degree (~6 km) observationally-based historical (1915-2006) climate dataset (daily maximum temperature, minimum temperature, and precipitation). These are combined with climate projections using results from 10 Global Climate Model (GCM) simulations of 21st century climate (following the A1b and B1 scenarios), downscaled to 1/16th degree using the Composite Delta, Hybrid Delta, and Bias Correction and Statistical Downscaling (BCSD) methods of downscaling (Hamlet et al., 2010). These climate datasets are used to produce hydrologic products (e.g., runoff, evapotranspiration, soil moisture) for the historical and future climate projections using the Variable Infiltration Capacity (VIC, Liang et al., 1994) macroscale hydrologic model.
To produce the present dataset, the CBCCSP results were summarized at monthly time scales over both Bailey ecosections and Omernik level III ecoregions as well as the 8-digit and 10-digit Hydrologic Unit Code (HUC4/HUC5) basins (shown in Figure 1). The latter were used primarily to assess changes in runoff statistics and the snow season. Summaries are included for the variables listed in Table 1. Projected changes are summarized in tables, plots showing changes in the annual cycle, and maps showing the geographic pattern of changes. These results, as well as the methods used to produce the dataset, are all summarized in the project report.
Finally, we note another relevant CIG dataset (project website; Littell et al., 2010), which provides a simplified set of ecosystem-based summaries over a much wider domain. Covering nearly all of major basins in the Western U.S., this dataset is mentioned because it could be used to extend the present assessment to USFS lands in other regions.
|Variable||Variable Name||Units||Monthly Aggregation||Annual Cycle Table||Annual Cycle Figure||Map||Summary Table||Summary Plot|
|average daily temperature||tavg||°C||average||✔||✔||✔||✔|
|maximum daily temperature||tmax||°C||average||✔||✔||✔||✔|
|minimum daily temperature||tmin||°C||average||✔||✔||✔||✔|
|combined flow (runoff + baseflow)||combined flow||mm||total||✔||✔||✔||✔|
|low flow statistics||lowflow_gridcell_strflw_7dyflow||cms||n/a||✔||✔||✔|
|snow water equivalent (swe)||swe||mm||1st day||✔||✔||✔||✔||✔|
|date peak swe||jd_max_swe||days||n/a||✔||✔|
|date 10% accum||jd_10pc_accum||days||n/a||✔||✔|
|date 90% accum||jd_90pc_melt||days||n/a||✔||✔||✔|
|length of snow season *||numdays_10pcaccum_90pcmelt||days||n/a||✔||✔||✔|
|vapor pressure deficit||vpd||Pa||average||✔||✔||✔|
|potential evapotranspiration 1 **||pet1||mm||total||✔||✔||✔||✔||✔|
|potential evapotranspiration 3 ***||pet3||mm||total||✔||✔||✔||✔||✔|
|soil moisture, layer 1||soilm1||mm||1st day||✔|
|soil moisture, layer 2||soilm2||mm||1st day||✔|
|soil moisture, layer 3||soilm3||mm||1st day||✔|
|total column soil moisture||soilmoist||mm||1st day||✔||✔||✔||✔||✔|
* the length of the snow season is defined here as the number of days between the date that 10% of the yearly maximum swe has accumulated and the date when 90% has melted.
**pet1 is calculated following the standard definition of potential evapotranspiration: natural vegetation (including stomatal and canopy resistance), and no water limit.
***pet3 is the same as pet1 except with vegetative resistance neglected: it includes only the effects of land surface characteristics and climate on evaporative demand.
Accessing the Data
Please use the contact information below to let us know how you plan to use the data -- we'd really like to know!
- Project Report
- Climate and Hydrologic summaries for all of Oregon and Washington
- Climate and Hydrologic summaries over Omernik Level III Ecoregions
- Climate and Hydrologic summaries over Bailey Ecosections
- Climate and Hydrologic summaries over HUC4 basins
- Summary tables: each file lists the summary data for all Bailey, Omernik, and HUC4 domains
Funding for this project was provided by a grant from the USDA US Forest Service Region 6 Pacific Northwest Research Station.
Hamlet A.F. et al., 2010: Statistical downscaling techniques for global climate model simulations of temperature and precipitation with application to water resources planning studies. Chapter 4 in Final Project Report for the Columbia Basin Climate Change Scenarios Project.
Liang, X., D. P. Lettenmaier, E. F. Wood, and S. J. Burges, 1994: A Simple hydrologically Based Model of Land Surface Water and Energy Fluxes for GSMs, J. Geophys. Res., 99(D7), 14,415-14,428.
Littell, J.S., M.M. Elsner, G. Mauger, E. Lutz, A.F. Hamlet,, and E. Salathé. 2011. Regional Climate and Hydrologic Change in the Northern US Rockies and Pacific Northwest: Internally Consistent Projections of Future Climate for Resource Management. DRAFT report available online here.
Nakicenovic, N et al. (2000). Special Report on Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change.
Questions regarding this dataset can be directed to:
- Guillaume Mauger (firstname.lastname@example.org), (206) 685-0317