SEASONAL PATTERNS OF SPRING DISCHARGE AT SILVER FALLS, CROSBY COUNTY, TEXAS

Abstract

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 one such 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 flow rates over a seven-year period did not show an appreciable reduction associated with the depletion of the Ogallala aquifer; however, discharge was found to follow a seasonal pattern of declining flow during the summer followed by a recovery starting in late fall and reaching maximum discharge during 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 seasonal groundwater extraction for irrigation and the growth and transpiration of natural vegetation contribute to the observed seasonal patterns of groundwater discharge at Silver Falls.