A Deeper Look into California’s Water Resources

Category: Monitoring Drought
Project Team: California Water Resources
Team Location: NASA Jet Propulsion Laboratory – Pasadena, California

Average TRMM Precipitation (top), SMAP Soil Moisture, and GRACE Water Storage data from June 2015 over a Digital Elevation Model (DEM) of California (bottom). Image Credit: California Water Resources Team

Average TRMM Precipitation (top), SMAP Soil Moisture, and GRACE Water Storage data from June 2015 over a Digital Elevation Model (DEM) of California (bottom). Image Credit: California Water Resources Team

Justin Lawrence
Lauryn Gutowski
Nick Rousseau
Brittany Zajic

Dr. John T. Reager (NASA Jet Propulsion Laboratory)

Past/Other Contributors:
Nick Rousseau (Center Lead)


2015 marked the arrival of the strongest El Niño ever recorded, surpassing the 1997-1998 event that brought significant rainfall to the southwestern United States. As sea surface temperatures in the Central Pacific increased, it was forecasted that this event may have similar effects and alleviate what the U.S. Drought Monitor classifies as “exceptional” drought across California. However, the effects from the drought, now in its fifth year, continue to strain municipal and agricultural water supplies throughout the state. Our team used data from NASA’s Gravity Recovery and Climate Experiment (GRACE), Global Precipitation Measurement (GPM), Tropical Rainfall Measuring Mission (TRMM), and Soil Moisture Active Passive (SMAP) Earth observations, as well as meteorological surface observations from the National Oceanic and Atmospheric Administration (NOAA), and historical reservoir levels from the California Department of Water Resources to gain a more complete understanding of water resources in California. Together with our partners at NOAA’s National Weather Service (NWS) regional office in Oxnard, California, our study employs NASA Earth observations to better quantify impacts of the 2015-16 El Niño event and determine how much drought recovery occurred throughout the state over the course of the wet season. Specifically, monthly GRACE measurements of terrestrial water storage allow for a better understanding of subsurface resources, a parameter often omitted from drought assessments. We also analyzed monthly precipitation and temperature trends in relation to droughts and El Niño–Southern Oscillation patterns with climatological history from NOAA dating back to 1895.

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Sara Lubkin 16-09-2016, 13:28

Congratulations, California Water Resources team. Great job!

Dash Cruz (Chaco Canyon Cross-Cutting) 16-09-2016, 11:40

Congratulations on winning the VPS guys! I will be using this video at recruiting events to help boost recruiting efforts at Marshall!! Thanks and congrats again, you guys deserve it!

Nick Rousseau 16-09-2016, 13:15

Thank you, Dash! The efforts made by our team and the strong collaboration we had with our partners from NOAA made this project rewarding. We are delighted that you want to use our video for your recruiting efforts! Thanks again!

Kelsey Herndon 08-09-2016, 21:52

Impressive video! Did you guys use any model or develop your own algorithm to synthesize all of these datasets? How did your results help you to better understand the relationship between drought recovery and El Nino?



Justin Lawrence 09-09-2016, 09:24

Hi Kelsey, thanks for your question! We pulled data from many different agencies- NOAA, USGS, California Department of Water Resources, and of course NASA for all of the satellite observations. Once we had all of the data assembled we were able to compare El Niño/Southern Oscillation (ENSO) status with precipitation rates in California and learned that the picture is quite complicated when you look at resources on a statewide basis. It’s very difficult to forecast precipitation, and subsequent drought recovery, from ENSO.

We also worked on some basic modeling to better understand the relationship between precipitation and GRACE terrestrial water storage in California as well- stay tuned for more!

Julia Marrs 07-09-2016, 17:22

I really enjoyed that your video emphasized how serious the problem of prolonged drought is in California, while still keeping a sense of humor. Is there any plan to create a tool or other platform to bring your synthesis of these datasets to the wider scientific community or the public? It seems like this would be the team to do it! Congratulations!

Justin Lawrence 09-09-2016, 09:31

Thank you, Julia! Nick put together a great video. Together with our partners at the National Weather Service, we’re assembling a Story Map- essentially an interactive site that will help communicate our results to the wider community. We’ll post the link when it’s finalized, but you can check out one of our partner’s El Niño Story Maps here – http://noaa.maps.arcgis.com/apps/MapSeries/index.html?appid=7c068f2f7f2b4c8692570c22d38f9ab6

Dash Cruz 07-09-2016, 11:55

That was an amazing video! It really grabbed my attention from the beginning, I really want to go purchase this software now! Kudos to this collaboration.

Sean McCartney 07-09-2016, 09:43

Wow! I don’t know if it’s your location close to Hollywood, but I thought I was watching a thriller for the first minute of the video. Nice way to build excitement for what follows. Being a CA native, I’m curious what the biggest takeaways were from the project. How big of an impact did the 2015 El Nino have groundwater recharge? Thanks!

Alison Thieme 07-09-2016, 09:07

Exciting video! Did the data from the recent 2015-2016 El Nino season show any recovery in California’s water resources?

Brittany Zajic 09-09-2016, 02:01

Hi Alison,

Great question! We looked at both GRACE Terrestrial Water Storage (TWS) and reservoir data.
From the comparison of both, it was concluded that GRACE provides a more complete metric for water storage and drought assessment. The GRACE TWS anomaly remains nearly a full deviation below the climatological mean, meaning California is still in a drought. And reservoirs saw more drought recovery than GRACE TWS.

Sara Lubkin 02-09-2016, 15:26

Congratulations on making it to the finals! Did you get a chance to look at historical, non-satellite data? Is five years considered an abnormally long drought?

Brittany Zajic 09-09-2016, 01:40

Hi Sara,

Thank you for your question. Yes, we did look at historical NOAA meteorological ground observations. This data is NOAA’ s National Centers for Environmental Information (NCEI) nClimDiv dataset, which is monthly data derived from the Global Historical Climatology Network-Daily (GHCN-D), and dates back to 1895. While this current drought is not considered a particularly long drought for the state of California, it is considered to be severe due to the increase in overall temperature, leading on average to higher temperatures and increased evaporation.

Tom Nolan 02-09-2016, 14:16

Thank you, DEVELOP Team, for synthesizing the various data resources into a cohesive unit of observations. This is the type of work that needs to be done for most interested parties to get the whole and true picture. Keep up the great work!

Brittany Zajic 08-09-2016, 17:23

Thank you for your feedback, Tom!

Cher Osborne 02-09-2016, 13:51

“Great video! I’m really happy to see this researched being focused on California’s drought, it’s truly a daunting issue I don’t see going away anytime in the near future.”

Brittany Zajic 08-09-2016, 17:24

Thank you, Cher!

Daryl Ann Winstead (Mekong River Basin Agriculture) 18-08-2016, 16:10

Very great video! What programs did the team use over the course of the project? Thanks in advance for your response!

Brittany Zajic 25-08-2016, 14:09

Hi Daryl Ann,

Thank you for your question. All of the data processing and data analysis was performed in Python, using mainly the Pandas scientific data module/data analysis library.

Alec Courtright 17-08-2016, 10:56

Awesome video and great work on your project! It looks like your partners were really fun to work with. It looks like TRMM lined up very nicely with in situ data. Did you get a chance to compare GPM with in situ data as well?

Brittany Zajic 25-08-2016, 14:15

Hi Alec,

Thank you for your question. Because of the short time period of available GPM data, we did not correlate GPM with the NOAA nClimDiv dataset. However, there is a high correlation (r = 0.94) between historic NOAA precipitation data (nClimDiv) and TRMM TMPA Earth Observation data during the 14 year study period within the state of California.


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