1/9 Climate C Change a and t the R Rio G Grande David S S. Gu Gutzler wi with th Ne Nels Bj Bjarke, e, Sh Shale leene Chavarria a and Nolan T Townsend University o of Ne New M Mexico Elephant Butte Reservoir gutzler@unm.edu Jan 8, 2019 § Observed and projected climate change § The problematic future of snowmelt runoff § Lower flows / Increased stress on water resources
2/9 Observed T Temperature a and Pr Precipitation i in N NM large, ongoing trend no long-term trend (yet) lots of variability 1930 1970 2010 updated from NM Water Supply Vulnerability Working Group (2015)
3/9 Streamflow a and S Snowpack i in t the R Rio G Grande H Headwaters Rio Grande headwaters Q (Annual) southern Colorado Snow Course minimal trend (but earlier peak runoff) Sites Del Norte SWE (1 April) 1958 1980 2000 2015 ~25% decrease 1958-2015 Chavarria & Gutzler (2018)
4/9 Climate Pr Projections: D Declining Snow a and R Runoff End-of-Century Snowpack Change Mid-Century Streamflow Change Projected Rio Grande Hydrographs current climate - - - 2020-2050 - - - 2070-2100 3 different model projections (A1B-forced) Brown & Mote (2009) Hurd and Coonrod (2012) Milly et al. (2005)
5/9 Increasing i importance o of S Spring p precipitation f for R RG f flows Based o on 1 1 A Apr SW SWE 1958-1986 Apr-Jul Discharge [Mm 3 ] 1951-80 1971-2000 1986-2015 1987-2015 Bjarke & Gutzler (2019) In r recent d decades: 1 Apr SWE Reduced r runoff p prediction s skill f from SW SWE 1 Apr SWE Chavarria & Gutzler (2018)
6/9 Newer Pr Projections ( (CMIP5 P5, U US BoR BoR): ): Inflow i into EB EB Reservoir a at S San Mar Marcial al Observed and projected inflows into Elephant Butte Reservoir Distribution of annual flows at San Marcial see Nolan’s poster model output (natural flow) obs models models 1970 2020 2070 (1964-2013) (2021-2070) observed annual flows climate model simulation Townsend & Gutzler (2019)
7/9 Model Pr Projections o of S Snowpack a and S Snowmelt R Runoff in t the H Headwaters change in snowmelt runoff CMIP5/BoR models that reproduce historical huge changes in SWE and Q range project lower flows in !!! future decades ... more consistent with previous projections change in snowpack “Observationally Consistent ” Bjarke & Gutzler (2019)
8a/9 Snowmelt R Runoff i in a a C Changing C Climate: Long ng-term O Outlook f for t the U Upper R Rio G Grande 1. C Climate i is c changing i in w ways t that a affect t the R Rio G Grande, n now a and i in f future …. Temperature é , Snowpack ê …. No significant long-term trend in observed precipitation Only slight downward trend in total streamflow volume Shift in hydrograph toward earlier runoff peak 2. S Snowpack ê is a associated w with R Runoff ê but p predictability o of Q Q i is d diminished …. Snowpack-based water supply outlooks are becoming harder …. Spring (post-SWE peak) precipitation is becoming more important .... Still anticipate lower flows from climate change as T é but uncertainty is large
8b/9 Snowmelt R Runoff i in a a C Changing C Climate: Long ng-term O Outlook f for t the U Upper R Rio G Grande 1. C Climate i is c changing i in w ways t that a affect t the R Rio G Grande, n now a and i in f future …. Temperature é , Snowpack ê …. No significant long-term trend in observed precipitation Only slight downward trend in total streamflow volume Shift in hydrograph toward earlier runoff peak 2. S Snowpack ê is a associated w with R Runoff ê but p predictability o of Q Q i is d diminished …. Snowpack-based water supply outlooks are becoming harder …. Spring (post-SWE peak) precipitation is becoming more important .... Still anticipate lower flows from climate change as T é but uncertainty is large
9/9 Nevertheless t this y year l looks b better t than 2 2018! Snowpack Rio Grande Headwaters NRCS Water Supply Outlook Based on 01 Apr 2019 forecast values Northwestern Rio Grande in Colorado 2019 50% %of max 30% 70% min 30-yr Forecast Point KAF avg KAF KAF KAF KAF avg avg -------------- --- --- --- --- --- --- --- RG / Del Norte 720 140 930 800 645 535 515 (APR-SEP) 2018 Current M Median O Outlook: 140% o of l long-term t total d discharge N D J F M A M J
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