This report provides information for planning, developing, and managing the water resources of the study area, which includes about 9,000 square miles of the Mississippi Alluvial Plain and about 2,000 square miles of the Springfield - Salem Plateaus. The study consisted of 2 phases. First, to collect and analyze data to gain a concept of the aquifer's geometry and hydrologic properties, the location and nature of its recharge and discharge boundaries, and its relation to streams and other aquifers. The second phase involved a simulation of the aquifer by a digital computer model that would provide estimates of response to pumping stress on the aquifer.

The report includes

• A location map of the study area
• A discussion of the region's geohydrology
• A table of records of 45 test holes used for control in geohydrologic sections
• A discussion of the lithology and stratigraphy of formations affecting the alluvial aquifer
• A detailed discussion of the alluvial aquifer, including its extent and geometry, lithology, hydraulic properties, flow boundaries, hydraulic head conditions and distribution, direction of flow, and water use
• A table showing the results of aquifer tests for 23 wells
• A table showing yield and specific capacity for 52 wells in the alluvial aquifer
• A table showing use of water by county from the alluvial aquifer, in acre-feet, for 1973 *Discussions of water-level fluctuations and declines, and water quality
• Digital model of the alluvial aquifer, giving design and assumptions, calibration values, and results for both steady-state and nonsteady-state simulations
• Diagram showing the history of water useage related to rice acreage and pumping rates west of Crowley's Ridge from 1911 to 1978
• Graphs depicting measured water-level declines, calibrated-model declines, and sensitivity-test declines for two wells measured from 1953 to 1979
• A graph showing stream-flow capture by ground-water pumping for L'Anguille river, St. Francis river, Bayou de View, and the Cache river from 1911 to 1978 with projections for two different pumping rates through 2001
• A plate showing the geohydrologic map of the Cache and St. Francis river basins with the locations of 5 cross sections
• Five cross sections of the Cache and St. Francis river basins
• Map showing altitude (elevations) of the base of the alluvial aquifer, Cache and St. Francis river basins
• Transmissivity map of the alluvial aquifer, Cache and St. Francis river basins
• Potentiometric surface map of the alluvial aquifer, Cache and St. Francis river basins, spring of 1973
• Potentiometric surface map of the alluvial aquifer, Cache and St. Francis river basins, fall of 1973
• Hydrographs showing water-level fluctuations and declines in selected wells in the study area
• Map showing dissolved-solids concentration in water from the alluvial aquifer in the study area
• Map showing grid system of the modeled area, Cache and St. Francis river basins
• Maps showing modeled potentiometric surface of the alluvial aquifer for steady-state conditions, and at pumping rates 1 and 2 for year 2000

*Includes: 48 pages, 4 figures, 13 plates, 5 tables

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