Earth System Science Center and Department of Atmospheric Science at The University of Alabama in Huntsville

Herndon maps water in African desert

HUNTSVILLE, Ala. (Aug. 4, 2017) — For thousands of generations, Africans concerned about their water supply looked to passing clouds for relief.

Now, thanks in part to NASA’s SERVIR program and several UAH students and employees, many of Africa’s leaders will increasingly be looking to the cloud when they have questions about water resources.

Four people with UAH’s Earth System Science Center, including graduate student Kelsey Herndon, spend time in Ghana during the early summer teaching officials from several African governments, NGOs and universities how to use Google Earth Engine.

“In Accra, myself and three others from SERVIR taught a workshop on using Google Earth Engine for doing things like identifying surface water or burned areas, or determining vegetation health using satellite remote sensing,” said Herndon, a student in UAH’s ESS master’s program. “The great thing about Google Earth Engine is that you don’t have to have a super fast computer or Internet connection, which tend to be limiting factors in developing countries.

“All the calculations are done on the cloud, on Google’s computers, which is nice.”

“This is pretty cutting edge stuff,” said Dr. Robert Griffin, who is Herndon’s thesis advisor. “I think we’re going to see quite a lot of this type of work migrating to the cloud, where you can do ultra-fast processing without tying up your own desk top computer or laptop, potentially for days at a time.”

A graduate research assistant affiliated with SERVIR, Herndon works with the SERVIR office in Niger, in west Africa. Her thesis research uses satellite sensors to map surface water in the sub-Saharan country, where average annual rainfall can vary from 23.5″ in the south to less than half an inch a year along the southern flanks of the Sahara.

“I’m trying to understand how climate and land use change will affect the availability of surface water, especially in the Sahel (a semi-arid region along the southern edge of the Sahara),” she said. “There are a lot of pastoralists (cattle herders) and small holder farmers there who depend on surface water.

“I’m particularly interested in ponds and lakes, and I’m focusing on the Tahoua region in Niger.”

Herndon is looking at several factors that influence water supply, including factors that are environmental, economic and political.

“There is a lot of political play,” she said. “Some of the areas we’re looking at that were previously rangeland for pastoralists are now being sold to, so now you have increased farming in areas where historically pastoralists were allowed to graze their herds. Pastoralists lead a nomadic lifestyle, moving into different areas as the seasons change.

“In Niger there are areas that are being transformed from grassland to farm fields, and other areas that are affected by desertification. We’re looking at temperature and precipitation, and at the intensity of episodes of precipitation and how that can affect the distribution of surface water.

“It’s an important issue,” Herndon said. “In arid regions, water is a scarce resource, so you have increased competition for access to it, which can contribute to conflict between pastoralists and the smallholder farmers.”

Using LandSat images, plus precipitation data from NASA’s Tropical Rainfall Measuring Mission and land surface temperature data from other satellite instruments, Herndon is developing algorithms “we can apply to pull out the extent and location of surface water so we can analyze how it has changed over time and how it might change in the future.”

In addition to teaching at a workshop and attending a conference in Ghana, Herndon also other toured parts of the country, including the Akosombo Dam across the Volta River in southern Ghana.

“It supplies half of the country’s electricity,” Herndon said. “But as the demand for electricity is increasing, there also is less water filling the reservoir. This is caused in part by a decrease in rainfall, especially in the northern parts of the watershed.

“They’re also seeing an increase in the number of small reservoirs being constructed by farmers, especially in northern Ghana and southern Burkina Faso. Those are holding back water that in the past would have flowed down the Volta.

“We’re trying to help figure out the best ways to manage water in this region,” Herndon said.

Originally from Birmingham (Inverness), Herndon received a B.A. in anthropology at Auburn University and an M.A. in anthropology at The University of Alabama, Tuscaloosa.

“Now I’m shifting my studies toward the application of Earth system science,” she said.

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