Coupling Field Data and a Flow Model to Characterize the Role of Groundwater in a Montane, Semi-Arid, Headwater Catchment, Gordon Gulch, Colorado | CU Experts

Groundwater is critical in sustaining streamflow, especially in mountain; catchments, because of its ability to supply baseflow in the absence of; precipitation. In water-limited arid and semi-arid mountain; environments, the need to characterize groundwater recharge and; discharge has grown in tandem with demands to effectively manage current; and future water resources. However, studying groundwater is challenging; in complex terrain due to limited field measurements. Nearly a decade of; monitoring data collection at Gordon Gulch in the Colorado Front Range; provides a unique opportunity to study such an environment. The field; data is used to parameterize and calibrate a groundwater flow model; (MODFLOW-NWT). Model results reveal spatial and temporal patterns in; groundwater recharge and discharge to the stream. Groundwater is; recharged primarily by one to two recharge events each year, driven by; spring snowmelt and rain. The majority of groundwater recharge occurs in; upper Gordon Gulch and is stored in saprolite and weathered bedrock.; Groundwater is discharged to the stream via long, deep flowpaths sourced; from upper Gordon Gulch and short, shallow flowpaths from soil and; saprolite in lower Gordon Gulch. Using Gordon Gulch as a case study,; this model and data analysis contribute to a larger effort to understand; and constrain the mechanisms driving groundwater recharge and; groundwater-stream exchanges in semi-arid, montane environments.

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