Modeling Stream-Aquifer Interactions on a Reach of the Upper San Pedro River Basin, AZ, by Integrating KINEROS and MODFLOW

RODRÍGUEZ LB; VIONNET CA; GOODRICH DC

San Francisco, California, USA

Conferencia; AGU Fall Meeting 2007; 2007

AGU - American Geophysical Union

In a groundwater model, the exchange with the surface water system is commonly simulated with boundary conditions. By the same token, in physically based rainfall-runoff models, the interaction with the groundwater system is represented in a simplified manner. Both approaches are defendable in many practical applications. However, in semiarid regions, stream/aquifer interactions play a critical role and a more integrated approach is advisable. Integrating two models commonly used in scientific and engineering applications is an approach successfully pursued by several researchers. In turn, that approach is the main concern of this short communication. A semiautomatic methodology that allows simulating stream/aquifer interactions combining two public domain codes, MODFLOW for groundwater flow, and KINEROS, for surface flow, is then presented. The feasibility of the approach was first tested against analytical solutions, were feedback from both models were exchanged by means of auxiliary computational codes. A study reach along the Upper San Pedro River, AZ, was selected to test the methodology in a real case situation. The site was selected due to its perennial character and well data availability for model calibration. Previous modeling efforts in the area were also a factor in the selection. No rainfall-generated runoff was simulated at this point, only a flood wave propagating through the reach interacting with the alluvial aquifer, including evapotranspiration from riparian vegetation. Exchange flows between subsurface and surface systems were computed as the flood wave traversed the study reach. Groundwater flow patterns and mass balance terms were acceptable for the study, establishing how feasible is to couple MODFLOW with KINEROS, though a more fine-tuning calibration is needed.