SNRI update on climate-change aspects of IRWM plan Roger Bales, Mohammad Safeeq & collaborators Topics in this talk Sierra Nevada climate Water balance Climate impacts Linking headwaters to groundwater Photo: Margot Wholey Dec 14, 2015

Extremes are part of California’s climate Variability & drought Extremes are part of California’s climate Mar 27, 2010 Mar 29, 2015 Apr 3, 2017

Multi-year dry periods are part of our Mediterranean climate 1100 yr drought record Reconstructed flows of San Joaquin R. Color shading marks below-median periods 4+ yr long 1-6 per century Multi-year dry periods are part of our Mediterranean climate Meko et al. 2014 DWR report www.wildlandart.com

Snow-line changes reflect temperature increases in the Sierra Nevada Rising snow line Snow-line changes reflect temperature increases in the Sierra Nevada Extremes in the past 100-1000 yr are not a sufficient guide to the future Mar 31, 2011 Apr 3, 2017

Kings-Kaweah-Kern snowcover Mar 31, 2011 Apr 1, 2017

Kings-Kaweah-Kern snowcover Mar 31, 2011 Apr 1, 2017

Giant Sequoia & drought Over 70 groves in southern Sierra Nevada Survived the 2011-15 drought Some quite vulnerable to a longer, hot drought Su et al., 2017 G. Rom, Flickr

Topics in this talk Sierra Nevada climate Water balance Climate impacts Linking headwaters to groundwater

California water balance Million AF Precip: 200 Applied: 80 Water supplies AF = 1233 Bm3 Agriculture: 80% (33 MAF) Urban 20% (8 MAF) Data from DWR, adapted from Nor. Cal. Water Assn.

Basic water balance Precipitation = Evapotranspiration + Runoff + ΔStorage = + snow & rain Evapotranspiration refers to evaporation, sublimation plus water use by vegetation

We can measure & manage evapotranspiration on a basin-wide basis Sierra Nevada Precipitation = Runoff + Evapotranspiration Map from CA Water Plan, 2013

Kings R. basin, annual water balance 1:1 line Streamflow is linearly related to precipitation, as evapotranspiration changes little from year to year

Multi-year whole-basin water balance Note that the 2016 value includes the effect of the 614 km2 Rough Fire. P = ET + Q - ΔS Bales et al., in review

Multi-year whole-basin water balance Note differences in the 2008-2011 (pre-drought) and 2012-15 drought). P = ET + Q - ΔS Bales et al., in review

Linking headwaters to groundwater Topics in this talk Sierra Nevada climate Water balance Climate impacts Linking headwaters to groundwater Lake Success CADWR photo

Shifts in California’s temperatures & why it matters Higher evapotranspiration Higher environmental flow Increase in the size of wildfires More heat waves, a longer frost-free season & fewer cold snaps A lack of snow accumulation during near-normal winter precipitation (a.k.a. warm snow drought) A shift in precipitation phase

Warmer temperature = more evapotranspiration (ET) Goulden & Bales, 2014

Kings R. average flow Sorabi et al., in preparation

Topics in this talk Sierra Nevada climate Water balance Climate impacts Linking headwaters to groundwater

Reconnecting a fragmented system Water in the balance – UC TV Sustainable California

Managing evapotranspiration Even thin Variable thin 1 km Control Managing evapotranspiration Stanislaus-Tuolumne Experimental Forest Basal-area decrease = 40-50% Control 0.5 0.6 0.7 0.8 0.4 0.5 0.6 0.7 0.8 950 570 340 0.4 Even thin Variable thin NDVI 150-200 mm/yr ET, mm yr-1 Control Even thin Variable thin 1985 1995 2005 2015 2.0 1.0 1000 mm Mean WY precipitation 1985 1995 2005 2015 Year J. Roche et al., submitted

1-day peaks increased by more than 3 fold Effect of temperature changes on groundwater-banking potential 90th percentile Flood flows Kocis and Dahlke, 2017 1-day peaks increased by more than 3 fold Sorabi et al., in preparation

Whole-basin integration is key for Central Valley Managed Recharge Opportunistic Recharge Reservoir reoperation Groundwater is our dry-period reserve; & sustainable use requires both more recharge & less extraction

Climate-change & headwaters: climate-modeling projections Historical variability in snowfall closely resembles the projected 2040-warming scenario (+1.8oC) By 2080s (+3.0oC), mountain snowfall will be reduced to 17 MAF, 30% lower than the average snowfall in 10 warmest years Snowpack storage in the Kings River Basin will decline by 50% under +4oC warming Water yield in the Kings River Basin will increase under warmer climate Flow will shift early in the year, i.e. more winter runoff

Management challenge Water security is a major challenge facing California Integrated water systems designed to manage green infrastructure & groundwater recharge is key to future water security

Comments? NSF Southern Sierra Critical Zone Observatory Spread them out throughout the basin but can be constrained. NSF Southern Sierra Critical Zone Observatory