The researchers studied the Arkansas River's water flow using tree rings to look back in time. They found that extreme high and low flows have happened in the past, even more extreme than what we've seen recently. Low flows across the river basin have been more common in the 20th and 21st centuries. The Arkansas River's flow affects flooding in the Lower Mississippi River Valley. When the Arkansas River has low flow, it can lead to major flooding in the Mississippi River. High flows in the Arkansas River have coincided with historic floods in New Orleans.