Skip to main content
U.S. flag

An official website of the United States government

Eyes on Earth Episode 35 – Watching the Water Supply with OpenET

Right-click and save to download

Detailed Description

Evapotranspiration is the process by which water transpires from the leaves and stems of plants and evaporates from the Earth’s surface. ET is an important metric for managing water use, but data availability has long been an issue. On this episode of Eyes on Earth, we talk about OpenET, a bold initiative whose goal is to improve water management by making that water consumption data more easily accessible to 17 western states. A consortium of agencies and organizations is working together to create a “one-stop shop” where users can access remotely sensed water consumption models on a single web-based platform.




Public Domain.


Hello everyone! Welcome to this episode of Eyes on Earth. Our podcast focuses on our ever-changing planet and on the people here at EROS and across the globe who use remote sensing to monitor and study the health of Earth. I'm your host, Steve Young. Today we want to talk about OpenET, a bold initiative whose goal is to improve water management by making water consumption data more easily accessible to 17 western states. A consortium of agencies and organizations is working together to create a "one-stop shop" where users can access remotely sensed water consumption models on a single web-based platform. Joining us to talk about OpenET are Forrest Melton, a Senior Research Scientist at NASA at California State University at Monterey Bay, Robyn Grimm, a Senior Manager of Water Information Systems a the Environmental Defense Fund, Justin Huntington a Research Professor at the Desert Research Institute, and Gabriel Senay, a Research Physical Scientist at USGS EROS. Welcome to you all.
Thanks, Steve.
Thanks Steve.
Let's start with you Robyn. Tell us what OpenET is.
Yes, thanks. OpenET is a web application and data system that's filling one of the biggest data gaps in water management, by making satellite-based evapotranspiration data, which is a critical use water metric, widely accessible to farmers, land owners and water managers across the western US. This is so important, I think because we are all aware here, water is a critical resource that is becoming scarcer across the arid west. The southwest has been suffering one of the more severe mega-droughts since the 1500s. And that turns into a challenge for farmers and water managers across the western are faced with constantly being asked to do more with less. In that situation, good and timely data are all the more critical. That's where OpenET comes in. OpenET leverages advances in technology and best available science to provide consistent, trusted data on how much water is needed to grow crops and is consumed by other plants and vegetation across the landscape.
So, Justin, tell us about the groups that are behind all of this, trying to make this happen. When could we see OpenET actually being used being launched?
The project is being led by NASA, the Desert Research Institute, Environmental Defense Fund along with a software development firm named HabitatSeven which specializes in visualization of scientific data. We are also partnering with Google and Google Earth Engine. We also have academic and federal agency partners including the USGS, US Department of Agriculture, Cal State-Monterey Bay and a number of other universities, including University of Idaho, University of Maryland, University of Nebraska at Lincoln. What is really unprecedented here is that the philanthropy dollars that have enabled this project have really encouraged collaboration instead of competition which is really helping us advance the science. As far as when we plan on launching it? It will be launched next year in early to mid-2021. 
It's called OpenET. Forrest, can you tell us about the ET part?
Sure. The ET in OpenET stands for evapotranspiration. Which is the process by which water is transferred from the land surface back to the atmosphere. That includes water that evaporates off the land surface and transpires from plants. ET, or evapotranspiration is one of the largest components of the water cycle. Because water vapor is invisible, we often forget that it is happening all around us every day. It is a critical piece of information for water management. If we are serious about managing increasingly limited water supplies, we've got to be able to measure where every drop goes. OpenET is going to help us do that. 
Is there anything you would like to add, Gabriel?
About 70% of the rain and snow in the US, ends up as ET, and even more in the arid west. ET is reported as a consumptive use in water management. Once ET occurs, the water is not available for the other uses, such as industrial or domestic purposes.
At what scale will OpenET be able to provide useable information? Justin?
OpenET will provide annual, monthly, and daily satellite-based ET estimates. These ET estimates will be at the field scale for 17 western states. The field scale is really important here, in that that is the scale in which water and water rights are managed in the west. Having that Landsat scale, the 30 meter by 30 meter pixel resolution is really important.
Forrest, I've heard OpenET described as potentially being revolutionary. How so?
OpenET is going to make this critical water data widely available to everyone. So that policy makers are looking at the same data as those who are being affected by policy decisions. And farmers, whether they are large operations or small family farms, water districts big and small, they will all have access to the same information. Which is really important to ensuring that we are working from essentially the same sheet of music and have a shared basis for decision making moving forward. 
Why now? Why OpenET now? Why haven't we done this years ago?
There's a couple of reasons for that. If Landsat data wasn't freely available we wouldn't be able to do this. The USGS also made Landsat Collection 1 available on the cloud and accessible through the earth engine platform. That really opened up a whole new area of research in terms of developing fully automated approaches to mapping evapotranspiration as scales the size of the western US. Over the last few years, the science community has not only developed the software systems to be able to process that data in close to real time, but to do it at scale and also to share a code through open source software repositories. These advances have allowed OpenET to proceed at a pace that I would not have thought would be possible 5 years ago.  
You all have mentioned some of the different water managers, the resource managers, others who would be interested in OpenET, farmers. Can you give me some specific examples and tell us who is really going to out there wanting to grab on to this and why? Give me some examples.
In central Nevada, there is an over appropriated ground water basin called Diamond Valley. Farmers have been asked to reduce their consumptive use by 40% to get the basin back in balance. As of late, they have put meters on all wells. But, we don't have meters going back in time. Getting a good understanding of what is the historical long-term average consumptive use in the basin and comparing it to existing estimates knowing just how over appropriated that ground water basin is, is really a game changer. It is bringing best available science to these hard questions that we haven't had good answers to in the past. It is already working. We've been looking at OpenET data over Diamond Valley for specific fields where we know conservation efforts by the farmers have been put in place, where they have reduced irrigation, they don't go for that last cut of alfalfa, they start irrigating a little bit later in the season. We are in fact seeing declines in evapotranspiration for those fields. 
Anyone else have examples they want to say?
Yes. I also want to add that a primary goal of the OpenET project and platform is to make the data broadly accessible to really anyone who needs it. The end product will include a data explore page that has wide public access for users to be able to browse monthly or annual ET estimates for any field within the western US for the last 5 years. In terms of users and folks who we think are going to pick up on the data and apply it, there's some similar applications in California. The one that Justin just mentioned in Diamond Valley. OpenET is being used by a water district in the Kern Sub-Basin in California. Which is one of the state's most critically over-drafted basins. They are facing a similar reality where they having to figure out ways to help growers and landowners navigate the requirement of reducing water use. This particular district has set up a new online accounting platform for landowners that's really built around data provided by OpenET. With the intent being, to help them understand how their water use is changing across the growing season. Basically, the district manager there compares it to somebody being able to go online and check the balance of their bank account in terms of their water allocation. He is also thinking that potentially this could form the county baseline for an eventual trading program within that basin. There is a different application happening in the Bay Delta, which is basically the hub of California's water system. Where the Delta Water Master are working for the State Water Resources Control Board is proposing an alternative plan of compliance there for a regulation that requires all landowners and growers to report on their diversions. In the Delta, that is an incredibly costly and time extensive regulation to comply with in the sense that they are having to put meters on all of the syphons and infrastructure that brings water on and off of those islands. The thought here is that OpenET can provide a much cheaper more cost-effective way of complying with that regulation and really ease the burden. I think Forrest may be able to speak a little bit to some of the more local scale applications in terms of how farmers and growers can use this for irrigation management and other decision making processes.
Yes. Thanks, Robyn. For farmers in particular, we see value in OpenET in terms of allowing folks to easily get access to information that is going to help them balance irrigation applications to match the crop water requirement. Growers have to account for salinity management, the timing of operations in the field. But, at the end of the day having access to information on evapotranspiration, I think can really help advance the use of data driven irrigation management practices and also help them document the benefits of past investments in water conservation. Incorporating ET information can actually can actually reduce applied water by anywhere from 20 to 40% relative to some of the more traditional used data irrigation schedules while preserving crop yields and also reducing demand for fertilizer. Because when you match irrigation to what the crop really needs you end up leaching a lot less water. Which means that the fertilizer stays in the roots on the plants where the plants can use it. They are showing reductions in fertilizer applications of up to 50%, again while sustaining crop yields and quality.
I'll just add to that, if it's ok. We touched upon a lot of different example applications. One of the ones that I don't know that we have spoken about too much yet, that we think is another really important use of this, is the development of incentive driven conservation programs that really tie incentives or payments or other types of credit to actual reduced water use in terms of consumptive use. The hope is that allowing for a lot more creativity and scaling of those types of programs help to protect the financial viability of farms and communities during times of drought and scarcity and ensure that these plans are built off of an accurate understanding of a water budget.
One of my questions is, You've made reference to the fact that there are six models that are part of OpenET, does that mean that it's a collaboration of all six? Are you blending them all together? Do people go in and pick and choose which model they are interested in? How does that work?
The OpenET is providing access to information from these six models. In the past, a key challenge for water managers has been the fact that there are these different estimates. Folks can get stuck on trying to understand what is the right number? Why are they different? How do they compare? What OpenET provides is a way for folks to easily look at the different estimates. But, more importantly, we're conducting what's I think the largest intercomparison and accuracy assessment for satellite-based ET performed to date. What the community is developing is a consensus view of what an ensemble value should be. So out of those six estimates, which models are performing well for different crop types, landcover types, seasons, regions. From those models that are performing well, producing a single estimate for every field of every location in the west for each time period that data is available from OpenET. That's daily, monthly and annual. 
Gabriel, Can you tell me what role the USGS and EROS has played in this effort?
USGS EROS has been part of the initial discussion, since the inception of OpenET. Particularly implementing the EROS developed model, SSEBop model, It is such a mutual. On the one hand USGS contributes to improving the ensemble product that Forrest mentioned. and this improves the SSEBop model which in turn then improves the ensemble. So it is really a two-way relationship between USGS and OpenET. It is a win-win arrangement.
Steve, I'll just add to that. Landsat has been an invaluable data source for OpenEt. OpenET wouldn't be possible without Landsat. The 30 meter by 30 meter resolution in the visible near infrared and 100 meter resolution in the thermal is essential to our ability to produce data from OpenET at field scales. In addition, the open data policy, freely accessible data and the ability to access data from Landsat on the cloud through earth engine makes OpenET possible. We really appreciate the work by EROS to think creatively and be innovative in making data available in ways that not only support science but also the development of applications like OpenET.
We've been talking about an important new initiative called OpenET which is going to launch in 2021 and will give users access to multiple water consumption models on a single web-based platform. Some are calling this revolutionary. Forrest Melton, Robyn Grimm, Justin Huntington, and Gabriel Senay, thanks for joining us.
Multiple Responses: 
Thank you, Steve, it was a pleasure.
Great talking to you. 
Thanks so much for having us. 

This podcast is a product of the US Geological Survey, Department of the Interior. Thanks for joining us. 


Show Transcript