KNOBEL, AR — EnSafe
earned the top category honor in the American Council of Engineering Companies (ACEC) of Tennessee
’s Engineering Excellence competition. Winners were announced at the ACEC annual awards banquet held in Nashville. The Grand Award presented to EnSafe was in the category of Water Resources for a Hydrology and Hydraulic Modeling project performed in support of the Dave Donaldson Wildlife Management Area (DDWMA) near Knobel, Arkansas.
About the DDWMA
The DDWMA is home to one of the largest remaining tracts of bottomland hardwood forest habitat in Eastern Arkansas, attracting migrating waterfowl to the DDWMA’s hardwood acorns and large pools of water. This vast natural setting is a leading driver behind area tourism, a vital economic resource locally and state-wide.
Prolonged Flooding Proved Destructive to Hardwood Trees
The DDWMA contains a complex network of levees, water control structures, and canals installed in the 1950s and ‘60s to capture water during the winter months, enhancing migrating waterfowl habitat. Unfortunately, unexpected increased flows in the Black River during the tree’s growing season resulted in prolonged flooding that proved destructive to the hardwood trees. This, in turn, impaired ecology for forest wildlife, decreased acorn production, lowered populations of migrating waterfowl, and reduced the overall population of migrating waterfowl visiting the DDWMA, hurting area tourism and reducing state revenues.
Team Collaboration to Develop a Plan
EnSafe worked with Ducks Unlimited and the Arkansas Game and Fish Commission (AGFC) to develop a plan for restoration and conservation of this critical habitat through innovative water resource science and engineering. EnSafe’s engineers developed a unique and intricate two-dimensional (2D) hydraulic model (HEC-RAS) that assisted the AGFC in selecting the appropriate modifications to balance in-flows and out-flows from the vast 24,000-acre DDWMA, both at the macro and micro level.
EnSafe calibrated and executed a hydrologic model of the DDWMA’s 1.4 million-acre watershed to determine unsteady-state inflows into the DDWMA, conveyed through the Black River. This provided critical understanding of the timing of the river’s flows, especially at peak levels.
24,000-Acre 2D Model Proves as “Game Changer”
But it was EnSafe’s innovation in developing and calibrating an unsteady-state 2D HEC-RAS model of the 24,000-acre DDWMA, with its miles of levees and 37 water control structures, that proved to be the project’s “game changer.” This complex model was crucial to understanding how the river influenced the DDWMA, the flow throughout the Greentree Tree Reservoirs, and how to evacuate the DDWMA’s flood waters faster during the river’s low-water conditions.
This intricate 2D model provided the resolution needed to reduce flooding on a macro and micro level, where inches of surface water elevation made dramatic differences in large swaths of area. These details simply could not be realized with less sophisticated models and provided detailed flow insights never before understood.
EnSafe’s water resource engineering expertise and use of an innovative hydraulic model will help to restore the bottomland hardwoods, protect the local ecosystem, preserve the waterfowl population, and reinvigorate area tourism for increased revenue and preservation for future generations of both conservationists and waterfowl sportsman alike.
The project team was led by Director of Engineering Chris Triplett, PE, PMP, and Water Resource Professional Meaghan Owens.