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UCA Geographers Awarded NASA Grant to Study Arkansas Delta Irrigation

Matthew Connolly and Marisol Filares measure the height of soybean crops. Photo contributed by Yaqian He and Matthew Connolly.

University of Central Arkansas geographers have received $40,000 from NASA to study how the Arkansas Delta’s declining fresh groundwater supply for irrigation can affect local climates and crop yields.

The study is led by Yaqian He, Ph.D., an assistant professor of geography, and Matthew Connolly, Ph.D, an associate professor of geography, who received the grant from NASA’s Established Program to Stimulate Competitive Research (EPSCoR). Through their research, the UCA team is studying irrigation and climate patterns in the northern Arkansas Delta region, such as Jackson County, Arkansas.

The water supply is essential to life, and no industry knows that more than agriculture. This team of geographers is keen to study the area’s water supply because of its effects on crop production and the climate.

“Arkansas is facing a severe issue with groundwater depletion due to over-pumping for irrigation water,” said He. “We are using our backgrounds in waterways, climatology, and remote sensing, to see if we can find over-irrigation and potential best irrigation practices.”

Yaqian He and Marisol Filares take measurements with a GPS device. Photo contributed by Yaquin He and Mathew Connolly.

“It’s important to study this in the Delta because of its large agricultural productivity and the importance of agriculture on the state’s economy,” Connolly added.

The amount of water involved in irrigation is enormous, and the fertile fields of the Arkansas Delta are dependent on groundwater. About 80% of irrigation comes from under Earth’s surface, He said.

“As agriculture is continuing to develop and the population is growing, water resources may be limited. A sustainable irrigation strategy may be needed for Arkansas,” He said.

The main concern is overdraft that occurs when groundwater is pumped at a faster rate than it can be replaced.

Overdraft can have a dramatic impact on a host of activities. When pumps exhaust the fresher water that stays close to the surface, deeper water that contains higher mineral content and salt reach croplands. This leaves room for potential problems like lower crop productivity, as the salt concentration changes the soil chemistry.

Applying groundwater to crops also creates differences in the climate on a local level—called a microclimate. This happens as the temperature and moisture characteristics are distinctly different from the surrounding region. Groundwater for irrigation also reduces soil moisture and increases water available for evaporation into the atmosphere.

Through their research, He and Connolly are using satellite and drone technology to determine what phenomena are happening in the Arkansas Delta.

Crossing Jackson County, they identified farmland to study with the help of the University of Arkansas Extension Service in Jackson County. This collaboration connected the UCA team to farmers, allowing a more practical understanding of how often farmers irrigated their crops.

He and Connolly hired two undergraduate students, geography major Marisol Filares and environmental science major Caden Rhodes, to join the team. The grant allowed everyone to gain the Federal Aviation Administration’s remote pilot certification needed to fly the drone.

The team conducted fieldwork over the 2021 summer, studying crops on the ground and collecting imagery with satellites technology and a drone. As preliminary results become available, Rhodes creates an interactive map that disseminates information to collaborators. Ultimately, farmers will be able to use the study’s results to make strategic decisions on how often to irrigate farmland.

“One of the goals of this project was to try to help farmers to apply their water more judiciously, so that you’re not overwatering when you don’t need it,” Connolly said.