Keeping Track of Water in the Soil

Cartoon of a confused person wondering where the rain is.

"I was just kidding. I love rain! Come back!"

Rainy days can be a bit of a bummer. For many, a rainy day means being pent up inside and missing out on all kinds of fun outdoor activities. Cancelled baseball games. No afterschool soccer. Who needs that?

The state of California does, actually. California is in the middle of its third year of intense drought. If you are an outdoor enthusiast who dislikes rain, California is probably the place for you! You can count the number of significant rainstorms California has experienced over the last year on one hand. The past two winters have been among the driest since record keeping began in 1879.

Problems for California Farmers

Don’t pack your bags just yet. Despite it putting a crimp in your outdoor fun, rain is actually vitally important. Not only do the millions of people in California need water to drink, California farmers also need to figure out how to grow their crops (that feed and sustain us) with less water. This continues to be a bigger challenge as the drought grows more severe.

Map of drought conditions in California in 2013 and 2014.

Things are getting very, very dry in California. Credit: NOAA/NCDC.

It’s not hopeless, though. There are steps farmers can take to prepare to give their crops the best chance for success in hard times. Farmers can change the time of year when they plant crops, or in extreme cases, can switch over to other more drought-tolerant crops to remain profitable.

But making these big decisions requires detailed knowledge about how much water there is on a farm and how much water there might be in the future. One of the most important things to know is the amount of moisture in the soil where their crops grow.

New Challenges and New Tools

Artist's rendition of SMAP.

Art work showing SMAP.

In the past, the best way for farmers to figure out this sort of thing was to put sensors in the ground all around their fields—a time-consuming and expensive process. Otherwise, farmers simply relied on their experience and observations.

But soon there will be a new way to look at soil moisture—from space! NASA has a new satellite called Soil Moisture Active Passive (SMAP for short) that can measure soil moisture using special kinds of sensors (or instruments). While there have already been satellites that measure soil moisture, this one will be a big improvement. It will calculate soil moisture across the entire globe every three days and with a high level of detail too!

Droughts are challenging for everyone. People will have to make big changes in how they use water, and new technology will have to be developed to use water more efficiently. SMAP is just one part of the equation, but it could end up being a really helpful one.

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