Orange County Sustainability Collabora2ve Panel 1 Imported Water Resources Groundwater Deple5on Impacts of Climate Change

Transcription

1 Orange County Sustainability Collabora2ve Panel 1 Imported Water Resources Groundwater Deple5on Impacts of Climate Change Stephanie Castle 11/10/2014

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3 What is GRACE? Gravity Recovery and Climate Experiment: two satellites in tandem orbit, launched March, 2002 Precise measurements of the distance between the two satellites now yield highly accurate maps of the Earth s gravity field at monthly and longer intervals.

4 What is GRACE?

5 How does GRACE provide hydrological informa2on? Over land, GRACE sees varia5ons in all of the water stored on land (i.e. snow, surface waters, soil moisture and groundwater) at monthly and longer 5mescales...or varia5ons in total water storage (S TOTAL ) It works best for large areas (>150,000 km 2 ) and for longer 5me periods (> 1 month)

6 Trends in Freshwater Storage from GRACE April 2002 June Colorado River Basin and the Rocky Mountains - California and the Sierra Nevada Mountains Famiglie\ et al., in prep

7 Colorado River Basin Lake Powell Lake Mead Castle et al., 2014 USGS, 2013

8 Management During the Recent Drought in the Basin Lake Powell Water Balance - - Inflow to Powell - - Ou[low from Powell - - Powell ds/dt - 90% of streamflow in the CRB originates from Rocky Mountain snowmelt in the Upper Basin - Below normal inflow periods in late 1970s, early 1990s and Surplus inflows in the past following below normal periods; however, recently we have not had a significant surplus recovery period - Reduced inflows threaten the en2re Basin Castle et al., 2014

9 Management During the Recent Drought in the Basin Lake Powell Water Balance - - Inflow to Powell - - Ou[low from Powell - - Powell ds/dt - The Lower Basin depends on regulated releases from Lake Powell as its main source of inflow - The ou[low from Lake Powell to the Lower Basin from has been the longest period in which regulated released were at the minimum of 9 MAF/year (Law of the River, 1922) - Popula2ons have also grown substan2ally since previous shortages making the current situa2on more dire Castle et al., 2014

10 Lake Mead Water Levels and Water Ra5oning Regimes

11 Drought in the Southwest In the news We have concluded that 75% of water loss in the CRB during the recent drought is due to groundwater deple5on Castle et al., 2014

12 Take home message - During the recent drought, the Basin has lost enough freshwater to fill two full Lake Meads - 75% of that freshwater was depleted from underground storage Castle et al., 2014

13 CALIFORNIA Total Water Storage Changes in the Combined Sacramento- San Joaquin River Basins California s Natural Water Sources Average Annual Precipita2on (mm) Dominant Source of Snowpack: Sierra Nevada Mountain Range Lake Mead Data from the NASA Gravity Recovery and Climate Experiment (GRACE)

14 California s Water Conveyance Systems Central Valley Project State Water Project Colorado River Aqueduct Figure modified from the Metropolitan Water District, Los Angeles - Local Aqueducts

15 Current Condi2ons in the State s Largest Reservoirs Compared to Historical Averages

16 SWP and CVP Alloca2ons and GRACE Groundwater???

17 10 Cumula2ve Groundwater Deple2on in the Central Valley USGS and GRACE Results Year USGS GRACE 8-10 Wet Wet - 8 Cumula2ve Groundwater Loss (km 3 ) Variable to Wet Variable to Wet Variable to Wet Cumula2ve Groundwater Loss (MAF) - 90 Variable to Dry Variable to Dry - 73 Dry Dry Dry Dry

18 Management Implica5ons Imported water resources are becoming more variable and are in regions that have the poten5al to experience prolonged droughts in the future When reservoirs are declining, groundwater has been observed to be increasingly used to meet the gap between surface water supply and our growing demands We need to think about the aden5on we put towards managing both surface water and groundwater in the future

19 New GW Policy in California & the federal/state $11 million deal in the Colorado River Basin California has finally passed a policy that will require ci5es/coun5es/water districts within California to develop sustainable groundwater management plans in their respec5ve water porfolios Water providers from four western states and the federal government announced an $11 million agreement to fund projects meant to counteract cri5cally low water levels in the Colorado River basin The Interior Department said that local water providers in Arizona, California, Nevada and Colorado will take part in the deal The agreement comes a week aker the release of a new study by researchers from NASA and the University of California, Irvine whose authors said the results showed a shocking deple2on of groundwater - Associated Press

20 Thank you Ques5ons?

21 Comparison to on- the- ground groundwater data

22 Gravity Recovery and Climate Experiment (GRACE) Water balance closure: estimating groundwater storage changes ΔS GRACE Castle et al., 2014

23 En2re Basin Upper Basin Lower Basin