Hyporheic exchange between surface water and shallow groundwater can be an important driver of stream functions, influencing temperature regulation, nutrient cycling, pollutant attenuation, and habitat creation. Traditionally, site-specific detailed modeling and monitoring are used to assess these benefits, however, these approaches can be time-consuming and difficult to scale. Consequently, there is growing interest in developing widely applicable predictive ecological models that identify when and where hyporheic processes significantly benefit stream ecosystems.
Here, we present predictive models for hyporheic exchange by linking flow characteristics to ecological outcomes in a range of Texas streams. We focus on riffle-pool sequences and use a two-step modeling framework: HEC-RAS for two-dimensional surface water simulations and MODFLOW for three-dimensional groundwater flow. Surface water elevations from HEC-RAS serve as boundary conditions in MODFLOW, allowing us to model hyporheic flow paths, rates, and residence times. Key metrics, including hydraulic conductivity, flow path geometry, and residence time are then compared with invertebrate and water quality data to identify patterns and develop predictive tools.
By synthesizing hydrologic and ecological data, we aim to provide efficient, broadly applicable models for evaluating the ecological functions of hyporheic zones. These models can be used as screening tools for assessing hyporheic zone functions, informing restoration actions, and better understanding how to scale up hyporheic zone benefits to large scales.