Niklas S Christensen

niklas@hydro.washington.edu
wk: 206.685.1796

Current Research:
 
Assessing the Hydrological Impacts of Climate Change on the Colorado River Basin

The U.S. Department of Energy/National Center for Atmospheric Research Parallel Climate Model was used to assess potential effects of climate change on the hydrology and water resources of the Colorado River Basin based on three climate conditions: an ensemble of three 105 year transient simulations based on business as usual (BAU) global greenhouse gas emissions, a control run based on static 1995 greenhouse gas concentrations, and historic (1870-2000) conditions. Transient monthly temperature and precipitation sequences for the Colorado River basin were extracted from the climate model simulations using a statistical bias correction and downscaling method, and were used to drive the Variable Infiltration Capacity (VIC) macroscale hydrology to produce streamflow sequences. Results for the BAU scenarios were summarized into Periods 1, 2, and 3 (2010 - 2039, 2040 - 2069, 2070 - 2098). Average annual temperature changes for the Colorado River basin were 0.5 °C warmer for control relative to historical, and 1.0, 1.7, and 2.4 °C warmer for Periods 1-3, respectively, relative to historical. Basin-average annual precipitation for the control climate was slightly (1%) less than historical, and 3, 6, and 3% less than historical for future Periods 1-3. Annual runoff in the control run was about 10% lower that for historical conditions, and 14, 18, and 17% less for Periods 1-3, respectively. Higher wintertime temperatures also caused peak runoff to occur about one month earlier. Analysis of historical and VIC simulated flows with a water management model showed that the reduced streamflows would significantly degrade performance of the water resource system, with average simulated total basin storage reduced by 27% for the control climate and about 50% in Periods 1 - 3 relative to historical. Colorado River Compact mandated releases from Glen Canyon Dam to the lower basin were met in 80% of years for the control simulation (vs 100% in historical), and only in 59 - 75% of years for the future runs. Annual hydropower output was also significantly reduced for the control and future simulations.

Top plot is Naturalized flows(blue) vs. VIC calibrated flows(black) vs. VIC projected 2040s flow(red) below Glen Canyon Dam @ Colorado Compact Point.  2040s flows forced by D.O.E. Parallel Climate Model 3, scenario 2a.

Publications/Presentations:

Effects of Climate Change on the Hydrology and Water Resources of the Colorado River Basin, Christensen, N.S. et. al., July, 2003. Journal of Climatic Change(in press) .pdf of final draft (.7 Mb)  

Evaluation of VIC and GOES shortwave radiation and albedos, Christensen, N.S. et. al., January, 2003 .pdf of paper  

Effects of Climate Change on the Hydrology and Water Resources of the Colorado River Basin, Christensen, N.S., October 4, 2002. UBC/UW Hydrology and Water Resource Symposium power point presentation  

Impact of Climate Change on the Management of the Colorado River Reservoir System, EOS Transactions, 83(19) p. S1336. (presented at AGU Spring Meeting, 5/30/2002) power point presentation  

Evaluation of the snow-covered area data product from MODIS in the context of hydrologic modeling, EOS Transactions, 81(48) p. F548. (presented at AGU Fall Meeting, 12/19/2000) web site of presentation