Mississippi Alluvial Plain (MAP): Water Use and Availability Program

Science Center Objects

The Mississippi Alluvial Plain is one of the most productive agricultural regions in the Nation and depends on groundwater for irrigation. The MAP area constitutes the third largest area of irrigated cropland in the United States. The area is approximately 29,000 square miles (19 million acres) and includes parts of the States of Missouri, Tennessee, Arkansas, Mississippi, and Louisiana.

The U.S. Geological Survey (USGS) Water Availability and Use Science Program (WAUSP) is supporting a regional groundwater availability study of the Mississippi Alluvial Plain (MAP) to provide stakeholders and managers information and tools to better understand and manage groundwater resources. The study focus is on quantifying the status of the groundwater system in the MAP and determining how groundwater resources respond to development.  Advanced characterization of the MAP, synthesis of field data, and numerical modeling will be used in the study as described on these web pages.

Mississippi Alluvial Plain
The Mississippi River Valley Alluvial Aquifer highlighted within the larger Mississippi Alluvial Plain

        The Mississippi Alluvial Plain (MAP) has become one of the most important agricultural regions in the US, and it relies heavily on a groundwater system that is poorly understood and shows signs of substantial change. The heavy use of the available groundwater resources has resulted in significant groundwater-level declines and reductions in base flow in streams within the MAP.  These impacts are limiting well production and threatening future water-availability for the region. Over 9 billion gallons per day of groundwater are withdrawn for irrigation, supporting agricultural production. Agricultural interests in the region are aware to the economic and environmental costs that may come from declining water supplies but lack the basic resource description and analytical tools necessary for effective decision making at a regional scale. Technical specialists working in various Federal and State agencies and universities have worked individually and in partnership over many years to address aspects of particular water issues in the MAP, but no single agency or group has had the resources to support a broad-based and comprehensive scientific effort.

        Accurate and ongoing assessments of water availability in the MAP region are critically important for making well-informed management decisions about resource allocation and sustainability, establishing best practices for water use, and dealing with predicted additional changes to the regional water cycle over the next 50-100 years. The goal of the MAP water use and availability project is to improve estimates of water availability for the present, past, and future in the MAP region, to aid water resource managers in making decisions that can help to sustain key agricultural and industrial practices


The USGS recently constructed a computer model of groundwater in the Mississippi embayment. This model was used to simulate the rise or decline of water level in a shallow aquifer. Water from this shallow aquifer is utilized by the agricultural based economy in the area. In the animation, groundwater levels decline more than 100 feet from 1870 to 2007 in some areas of the shallow Mississippi River Valley alluvial aquifer in Arkansas. When pumping is forecast to 2038, based on trends of past pumping amounts and climatic variations, areas with water level declines of more than 100 feet expand, extending into Missouri and Mississippi. Brian Clark, U.S. Geological Survey. Public domain

Project Scope and Objectives

The specific objectives of this program task, over the course of five years, will be study the following topics (each of the topics are covered in more detail within the “Related” tab):

        Each focus area of FY16 is designed with an emphasis on improved simulation of the MRVA within the MERAS model. Through each component, stakeholders can be expected to gain a refined understanding of the groundwater system and how to manage the resource, and allow a more robust tool in the groundwater-flow model that integrates all available knowledge of the system to provide better estimates of projected future conditions.


For more information on the USGS Regional Groundwater Studies, please visit the USGS Water Availability and Use Science Resources Program.

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