[Roaring waterfall, sprinklers]
[hail bouncing and rainstorm, trickling water]
[rain pouring down, single splash of water from rock]
Narrator: We live it every day.
It’s in our veins, it’s under our feet,
it’s in our meals, it drives our storms.
It changes the course of history itself. [helicopter sound]
[movie reel music] It’s that water cycle we remember from elementary school.
Movie reel narrator: This is the cycle of water, by which all life survives.
Narrator: But the picture is so much more varied,
so much more vital, than a few arrows can represent.
Trying to measure that complexity from both Earth and space
is an infinite task, but observations from NASA [music builds]
and many worldwide partners have led to quantum leaps in our understanding.
In the last 60 years, we’ve seen a revolutionary change,
from relying principally on ground measurements,
to satellite observations of rainfall, to worldide measurements
of rain and snowfall every half hour. From space,
we can now monitor soil moisture every few days,
and detect changes in aquifers deep underground.
[sounds of rainfall] But we can't see every drop of water, everywhere, all the time.
And water issues are incredibly localized –
as unique as the landscapes the water flows over.
To fill in the gaps, see the local picture,
and project into the future, we use powerful computer models.
These models pull in an incredible amount of data
like those daily scans of precipitation, but also rely on our understanding of the planet
from all those decades of ground-based hydrology and soil research.
In every corner of the Earth, these models help people understand
critical issues like water availability for irrigation
drought severity, flood risk, and the likelihood
of crop failures and famine.
One of the trickiest parts is understanding how we impact the water cycle,
with the multitudes of water use decisions we make every day, that lead to things
like diverting surface water, pumping from aquifers,
and changing our planet’s climate.
In addition to collecting data and running sophisticated computer models, NASA funds a robust
set of projects to help water managers across the United States address
their specific water issues, from crop forecasts in the Bread Basket,
to snow pack in the mountains, [crunching snow]
to flood risk from nearby rivers.
NASA's water-observing fleet will expand in 2021 with a satellite that will collect data on
surface water height and slope, which will enable estimation of river flows.
With these observations we will be able to observe
all the major parts of the water cycle from space:
precipitation, evaporation, runoff, and water storage.
Our view of Earth’s water cycle will never be perfect,
never be complete. But each advancement we make
holds the promise of helping us prepare for the future,
avoid conflicts and mitigate disaster, feed the world,
and make good decisions about our most precious resource.
[music fades]