Watershed Physical Processes

Measuring erosion on irrigation reservoir levees

Daniel G. Wren, USDA-ARS-Watershed Physical Processes Research Unit, Oxford, MS

Yavuz Ozeren, University of MS, National Center for Computational Hydroscience and Engineering

Michele Reba, USDA-ARS-Delta Water Management Research Unit, Jonesboro, AR

UM NCCHE

Acknowledgements

Carlos Alonso USDA‐ARS(ret.)Dennis Carman White River Irrigation DistrictKeith Admire NRCS National Water Mgt. 

Center

Watershed Physical Processes

Introduction• The Mississippi/Arkansas Delta region is one of

the largest agricultural production areas in the United States—about 7.1 million irrigated acres

• In spite of receiving around 55 inches/year of rainfall, irrigation is needed to both maximize yields and reduce risk

• Excessive groundwater withdrawals have exceeded recharge rates for some time

• Surface water storage in irrigation reservoirs is one strategy that is being used for reducing the use of groundwater

Problem: severe levee damage

Waves in an irrigation reservoir

Study site: Fisher Reservoir

Fisher reservoir in high wind

One season of erosion from a south‐facing levee in Fisher Reservoir

One season of erosion from a south‐facing levee in Fisher Reservoir

Pin erosion measurements

Erosion pin

Levee erosion measured using LIDAR

Soil losses at Fisher Reservoir

Maximum lateral losses by levee

Loss of levee volume

• About 1800 yd3 lost in one season• At $2/yd3 for repair, this is about $3,600• If this is typical, then 5 year maintenance would be $18,000

Where do we go from here?• Levee erosion mechanics—field and

laboratory research– Relationship between wave energy and

erosion• Reducing fetch

– Interior levees– Floating barriers

• Assess existing reservoirs for useful patterns– Effect of reservoir shape and orientation on

erosion

Laboratory work

Floating wave barriers

Floating wave barrier in laboratory flume

Interior levees

Inner levee system

Levees at Hunt’s reservoir

Questions?