Seasonal patterns of spring discharge at silver falls, crosby county, texas

Authors: Stout, John

Submitted to: Texas Journal of Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2020
Publication Date: 7/1/2020
Citation: Stout, J.E. 2020. Seasonal patterns of spring discharge at silver falls, crosby county, texas. Texas Journal of Science. 72(1). Article 6. https://doi.org/10.32011/txjsci_72_1_Article6.
DOI: https://doi.org/10.32011/txjsci_72_1_Article6

Interpretive Summary: The Llano Estacado of western Texas is a vast elevated plain located at the southern end of the Great Plains of North America. Beneath the Llano Estacado lies the Ogallala Aquifer, which supplies groundwater for a highly productive irrigated agricultural system. In Texas, farmers and ranchers operate under the rule of capture, which grants landowners the right to capture groundwater beneath their property. Unrestricted pumping has led to significant depletion of groundwater resources. Changes in the volume of stored water in the Ogallala Aquifer can alter the flow of natural springs along the eastern escarpment. These springs supply water to ranches in the rolling country to the east of the Llano Estacado. Reductions of spring flow can reduce the supply of freshwater available for livestock production. In 2012, a long-term study was initiated to investigate changes of spring discharge at a site located along the eastern edge of the Llano Estacado. Measurements of spring discharge over a seven-year period did not show an appreciable reduction associated with the depletion of the Ogallala Aquifer. However, this study did establish that spring discharge follows a seasonal pattern of significantly reduced flows during the summer and peak flows during the winter. It is likely that the combined effects of groundwater extraction for irrigation and the growth of natural vegetation contribute to the observed seasonal patterns of spring discharge.

Technical Abstract: Beneath the high plains of the Llano Estacado lies the southern extension of the Ogallala Aquifer, which provides a key source of groundwater for the region. Along the eastern fringes of the Llano Estacado one can find numerous natural springs that discharge from the Ogallala formation and provide a valuable source of freshwater. Large scale irrigation has altered hydrological conditions, which has influenced the flow of springs along the eastern escarpment. In late 2012, the author began a study of a spring located at Silver Falls in Blanco Canyon, east of Crosbyton, Texas. The goal was to monitor the discharge of this naturally flowing spring over a period of many years to establish temporal patterns. Measurements of spring discharge over a seven-year period did not show an appreciable reduction associated with the depletion of the Ogallala Aquifer. However, discharge at Silver Falls was found to follow a seasonal pattern of declining flow during the summer followed by a recovery starting in late fall and reaching maximum flow during the winter and early spring. Whereas seasonal variations of spring discharge can be measured precisely, the cause of these seasonal patterns is less certain. It is likely that the combined effects of groundwater extraction for irrigation and the growth and transpiration of natural vegetation contribute to the observed seasonal patterns of groundwater discharge at Silver Falls.