Site-Specific and Generalized Weir Design for the Mississippi Delta *

Abstract

The Mississippi Delta encompasses 3.0 million acres, of which 2.2 million are irrigated for staple crops such as corn, soybeans, rice, and catfish. The Mississippi River Valley Alluvial Aquifer (MRVAA) is used to irrigate this area; over the past 30 years, it has decreased 20 feet in depth, requiring efforts to increase aquifer recharge and surface water availability for agriculture demands. A weir constructed in a river pools water upstream, promoting aquifer recharge through infiltration and increasing the availability of surface water withdrawals. Weir placement is important to the success of aquifer recharge. In partnership with the Yazoo Mississippi Delta Joint Water Management District (YMD), we created a scalable weir design guide that will allow for broad implementation and increased water availability across the Delta region. The site for the first weir was selected as an area characteristic of the Delta region and will serve as an example for subsequent designs. The supplemental design guide will allow for further weir implementation in the Delta region by providing the necessary steps for a weir design process. Inputs will be easily accessible for non-engineers and the outputs will be designs for Professional Engineer approval. By providing YMD with this weir guide, they will be able to design and install weirs more quickly and cheaply than before, supporting agriculture and groundwater resources in the Mississippi Delta.