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Developing a Geospatial Model for Analysis of a Dynamic, Heterogeneous Aquifer: The Brazos River Alluvium Aquifer, Central Texas

Stephanie S. Wong1, Joe C. Yelderman Jr.1, and Bruce Byars2
1Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798
2Center for Spatial Research, Baylor University, One Bear Place #97351, Waco, Texas 76798

The Brazos River Alluvium Aquifer extends from Bosque County to Fort Bend County and is one of 21 minor aquifers in Texas. The aquifer is comprised of floodplain sediments deposited by the Brazos River. These sediments occur generally in a finingupward sequence ranging from gravels to clays. Beginning in the 1950s, water from the Brazos River Alluvium Aquifer was used for extensive irrigation. More recently, local utilization of this resource in Central Texas has been minimal. However, current drought conditions and the subsequent increasing demand for water, especially around urban areas such as Waco, have sparked renewed interest in shallow groundwater sources.

Shallow, unconfined aquifers such as the Brazos River Alluvium Aquifer represent management challenges due to their lithologic heterogeneity, fluctuating saturated thickness, and proximity to surface sources of contamination. Knowledge of physical characteristics and nature of the fluctuating saturated section is important for effective water resource development and management occurring in the Brazos Alluvium.

An additional impact on the Brazos River Alluvium Aquifer is extraction of floodplain sand and gravels, especially in the study area immediately south of Waco. This added dimension of spatial and temporal heterogeneity in the aquifer has not been well documented in the literature. Characterization of the impacted area is a first step to determining the effect of floodplain mining on aquifer framework and function.

The purposes of this study were to improve hydrogeological characterization of the Brazos River Alluvium Aquifer in its northernmost reach, and to develop a dynamic database for groundwater management in a heterogeneous unconfined aquifer using geospatial tools. Two specific objectives of this study are: 1) to examine the suitability of using well depth as a proxy for alluvium depth and thickness; and 2) to assess the temporal and volumetric impacts of floodplain sand and gravel mining using geospatial tools.


AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012