By Miles Brown
The laws of physics and fluid dynamics have not changed over the millenniums. Water still looks for the path of least resistance flowing from higher elevations toward sea level. But how engineers manage the U.S. Army Corps of Engineer reservoirs across the Little Rock District continues to evolve with every major high-water event. One person who has seen that evolution first hand for more than 28 years is Janis Jones, a hydraulic engineer with the Little Rock District’s Reservoir Control Section. “When I started in the Little Rock District, we used dial-up modems to download water level data every four hours and that data was loaded into our system via very cumbersome “automated” processes,” recalls Jones. “Now data is collected in almost real time, processed, and loaded into our file systems with more modern network technology and truly automated processes which allows our engineers more time to focus on the most important task – the operation of our reservoirs.”
Every day, the Little Rock water control professionals manage 12 reservoirs from southern Missouri to southwest Arkansas ensuring the congressionally authorized purposes of each lake are maximized. All Corps lakes within the Little Rock District have one purpose in common – to reduce the risk of down-stream flooding. Some have hydropower requirements and others supply drinking water to thousands of Arkansans. Two lakes have minimum flow requirements, and there are provisions for recreation at most of the District’s lakes. With all of these interests vying for the water stored behind Corps dams, the engineers managing the releases have their hands full. The water control mission really reaches a fever pitch during high-water years. This year levels in all 12 Little Rock District reservoirs rose rapidly in the late spring and early summer as three waves of storms dumped record rains across the region in a matter of just a few weeks. The upper White River lakes experienced major rises due to the runoff, and crested at levels that represented 83 percent of the available system flood storage in mid-June. Peak river levels in the downstream White River valley were greatly reduced as the runoff was stored in the lakes. Unfortunately this was only the most recent flood event in the White River basin. “In 2011, major flooding occurred on the White River and the problems were made worse by the very high levels on the Mississippi River,” said Jones. “The water we had to release from reservoirs upstream had nowhere to go at the confluence of the White and Mississippi rivers.” In the Little River system in southwest Arkansas, DeQueen Lake, which discharges into Millwood Lake, set a new pool of record this year cresting at 472.8 on June 3. In addition, Millwood Lake, which feeds the Little River, and eventually the Red River, set a new pool of record cresting June 14 at 282.9 feet. That is 24 feet above the top of its conservation pool. “This year, we held back as much water as possible at Millwood because the Red River was above flood stage for weeks. We worked with two sister Corps districts to coordinate our releases and minimize the risk of floods for communities along the Red River.” Reservoir control professionals have been managing water levels at District lakes for more than 60 years, but several of the flood events over the last quarter century have approached record levels.
“Every high water event is different to manage as we implement the water control plans and use our engineering judgment to adjust operations at each of the projects to hold flood waters back and then release the stored water as channel capacity allows,” explained Jones. “The heavy rains across Oklahoma, Arkansas and Missouri created some of the highest flows we have experienced on the MKARNS (McClellan-Kerr Arkansas River Navigation System),” said Jones. “We had not seen a flood event this late in the year in my 28 years.” Arkansas River flows peaked at more than 370,000 cubic feet per second and sustained high flows continued for almost three months because of the large volumes of flood storage being released from reservoirs in Oklahoma and the uncontrolled runoff in the river basin. The volume of water that flowed down the river during this historic flood event was the largest since the navigation channel was completed in 1971. One of the essential missions for the Corps is keeping key stakeholders and the public informed about lake levels, river flows and dam releases. To help emergency responders and community planners prepare for possible future flood events, the District Reservoir Control team members conduct what they like to call “Water Management 101” sessions. “We started Water Management 101 events back in 2008 just before one of the major flood events on the White River,” recounts Jones. “Now we conduct these events each year and try to visit all the major river communities across the District.” Now that Jan Jones is winding down her decades-long tenure as a key team member managing the water storage and flows of the District, she has taken a little time to look back at the years and the major high-water events. “My hope is that we have documented these historical events and lessons learned well enough so our experiences can be passed on to the less seasoned engineers just starting their careers in Reservoir Control,” said Jones. “It is cool to see the smart, young professionals eagerly soaking-up the knowledge. It is very rewarding to realize that they are eager, anxious to use the available cutting-edge technology, and more than capable to take over the reins and keep the mission of water control and protecting people, communities and our infrastructure on track.”