The Measure of Water

When the Arkansas River flooded this past May, the USGS took note. This is what they saw

IT’S A MORNING in May. By 9 a.m., Adam Jones, Bobby Connor and Neil Holaway are cautiously launching their U.S. Geological Survey boat from the flooded parking lot adjacent to the submerged boat ramp at Little Rock’s Murray Park. The 26-foot Silver Carp is alone on this part of the Arkansas River. “Comin’ up,” Adam softly warns as he powers the boat into the main river channel, and they motor about 2 miles downstream to a section of the river bounded by bluffs on the north and a levee to the south. The Silver Carp is the platform from which they will measure the volume of water flowing past Little Rock in the Arkansas River. This marks the third of five times they’ll visit this section of the river during the May-June 2019 Arkansas River flood.

The levee protects the area of apartments and office buildings along Riverfront Drive between the Rebsamen Park Golf Course (there were no tee times available on this particular Thursday) and downtown Little Rock. From where the men sit, the levee appears to be up to the task of holding the river at arm’s length. The levee should be high enough. Constructed with a mixture of sand, silt and clay—levees with higher amounts of sand are more susceptible to failure—it appears to be structurally intact. There are no trees to weaken its integrity. There are concerns that some other levees along the river are not high enough or haven’t been properly maintained. Dardanelle Levee near Holla Bend was breached, and Lollie Levee near Conway threatened to fail before floodwaters receded. The U.S. Army Corps of Engineers recently rated the condition of 20 levees along the river as “unacceptable.”

While gathering their thoughts, the three, almost in unison, reach for a jolt of energy—a splash of caffeine or sugar. Before hitting the river, the USGS crew had stopped to refuel their truck, the Silver Carp and themselves, (after making their measurements at Little Rock, they’d be heading upriver to Morrilton). For themselves they’d bought some water and soft drinks, some chips and a few candy bars. Bobby had brought a banana on board—that’s bad mojo on a fishing boat, but apparently not on the Silver Carp.

Their need for some energy called to mind the food and drink purchased by the North Little Rock Water Co. in April 1927, when its workers protected the company’s pumps and buildings from one of the most horrendous floods in Arkansas history. Provisions for the workers included 108 pounds of chewing tobacco, 25,400 cigarettes, 1,859 sandwiches, 5,064 bottles of soft drinks, 3,435 pints of milk and 395 gallons of coffee.

As they prepare to take the first measurement, conversation ebbs and flows between small talk about a lightning-scarred tree now standing in 10-foot-deep water and professional talk about the data coming in to their laptop computer. Each of the three is a seasoned hydrologic technician with many flood measurements under the belt of his life jacket. Still, there are the tensions associated with the need to get an accurate measurement and the inherent perils of a large flooding river. Two technologies are used in the measurement: GPS to keep track of the precise location of the boat as it moves across the river; and Doppler technology to continuously measure the depth and velocity of the water.

Adam is responsible for keeping the Silver Carp pointed more or less upstream, while also moving it along an imaginary line stretching from one bank to the other. Bobby manages the GPS and Doppler technologies to calculate the streamflow volume based on the width, depths and velocities. Neil’s job is to watch for trees and other hazards floating down the river and to help Adam and Bobby anyway he can. After making four passes across the river, the average flow is almost instantaneously determined to be 417,000 cubic feet per second, and the stage is about 26 feet. Typical flow for May/June, by comparison, is about 70,000 cubic feet per second.

The flow value will be passed on to the Corps of Engineers and the National Weather Service for use in flood-management decisions and flood predictions—both for this specific flood and for future Arkansas River floods. The flood later peaked at a stage of 29.71 feet on June 5.

Data, however, have their limitations in the telling of a human story.

IT’S A MORNING in June. After Arkansas River water levels recede, USGS crews get a chance for a short breather before settling into routine streamflow measuring trips and preparing for the next flood. Individuals and entities with floodwater in their homes, on their property or affecting other infrastructure don’t get a breather. A damage estimate will take some time to calculate, but more than 800 homes were flooded, and the flooding affected the rich and the poor, the urban and rural, and those with businesses along the river. Even if Arkansans were not directly affected by the flooding, there is always next time. Failing to plan is planning to fail—so they say.