Landsat in Action - Water Use with Molly Maupin and Gabriel Senay

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USGS Hydrologist Molly Maupin and USGS Research Physical Scientist Gabriel Senay discuss how Landsat imagery has been used by the National Water Census and in studying water use trends.


Date Taken:

Length: 00:05:15

Location Taken: Sioux Falls, SD, US


My name is Molly Maupin and I’m a hydrologist with the US Geological Survey in the water mission area. And I am the national water use science team lead. And, over the years, we’ve used satellite imagery to help us to get a across the landscape picture of water use and what the satellite data can help us with is showing how much water is evapotranspired from the landscape, and in the west, that’s a really big component of water use, because as you know, it’s dry, and a lot of water gets evaporated. So, that changes across the country, and the Landsat data is really good about giving us a complete picture across the landscape. My name is Gabriel Senay,  I work for USGS EROS. My title is a Research Physical Scientist. The main goal in the water census is how water is used. So its usually at the county scale. For each county they want to know how much water is used for agriculture, how much water is used for thermoelectric plants which is required for cooling purposes, and how much water is used for industrial. How much water is for domestic. So really, splitting of water use in to measure the water into it’s major uses. For us to be able to take the Landsat product, which is showing the evapotranspiration, or the consumptive use of water, across the landscape. In order for us to take that and put it into the context of our water use compellations, we focus on irrigation. So we need to discretize out those irrigated lands. We can monitor using satellite data, the rainfall variability and how evapotranspiration is happening. Which means, how much crop is grown in irrigation fields, or in rain fed systems. And that can be transferred into alerts. Security alerts. Because, ET is strongly, linearly correlated to food production. The more plants transpire, more likely, more grain is being produced. So ET can be used for drought monitoring purposes, but also indirectly we can monitor how much water is being withdrawn from the ground water. It's a computer model. It stands for Simplified Surface Energy Balance, and the OP is operational. It started out as a simplified surface energy balance model, and we operationalized it. Which means we simplified the modeling parameters, procedures, so we can apply it globally. Gabriel is a leader in his field. There’s a large body of literature that is showing his algorithm and others. Because, his is easy to understand. It is giving us the type of information we need at a resolution and over a time series that is helping us a lot. So, I think his work has been extremely valuable. Knowing how much water is being used, because of demand and supply, we’re going to match it. Do we have enough water to meet this demand? So knowing the water use will help us, well, maybe the water used in this component is becoming lower, so water will be available on other uses. So it will help you design or do we need to transfer water from one basin to another. So it will help you understand to design a system that will meet the demand. So that’s a major advantage, just knowing the trends as well. So, when you do it over the years, given water us is going up, or going down, because of the population movement and cities growing. Maybe water is moving from agriculture to domestic water use. The main question is, do we have enough water for the people, and also, not only for people, for the ecosystem. Thanks to the Landsat missions and EROS, these very valuable remote sensed satellite images are available and they have a lot of value in the fact that they’re regularly measured over the same geographic places on earth, so you can get this stream of pictures that help us to show what’s changing on the landscape, and often that change in the landscape can be reflected, or is part of the driving force in changes in water use.