Transient, integrated simulation of groundwater and surface water over the Continental US A representation of pre-development groundwater, surface water, and surface energy processes, which are driven by hourly forcing by NLDAS-II from the 1985 water year. At 1km lateral resolution, with 12TB of model output and 3TB of input, this is the first large-scale, high resolution simulation of its kind, capable of resolving complex interactions between climate, water and topography.

Groundwater-surface water interactions in the San Joaquin River Basin As one of the most productive agricultural regions of the United States and a major water resource for a growing population, the San Joaquin River basin in the Central Valley in California, is a case study in the water-food-energy nexus and sensitivity to a changing climate. Here, we seek to better understand the physical hydrology of the basin by simulating groundwater-surface water dynamics with ParFlow-CLM. Results suggest that mountain block hydraulic conductivity could account for 7-23% of total recharge in the Central Valley, an important finding for water resource management in California.

Groundwater-land surface-atmosphere feedbacks during the European 2003 heat wave By coupling ParFlow to land and meteorological models, the fully coupled water cycle from groundwater to atmosphere can be simulated, a novel exploration in that atmospheric models rarely incorporate a dynamic water table and three dimensional subsurface flow. This study couples ParFlow to the meteorological model over Europe during the 2003 heat wave in order to investigate the effects of various lower boundary conditions and configurations on land-atmosphere moisture exchange and thermal energy.

Continental water residence times Ever wonder how long water spends in the subsurface? Residence time and groundwater age are vital to ecosystem development and human consumption, but measuring residence time distributions is difficult at large scales. ParFlow may be used to estimate water residence time when used in conjunction with a Lagrangian particle tracking approach. A simulation of groundwater age across the continental United States allows unique insight into the relationship between geography, climate, and water residence time in major basins.

The effects of insect-induced tree mortality on water and energy in mountain headwaters The mountain pine beetle (MPB) has decimated the high elevation lodgepole and ponderosa pine forests of Western United States and Canada over the past two decades. ParFlow-CLM was used to diagnose feedbacks that land disturbance at this scale has on water and energy fluxes in the Big Thompson watershed in Colorado. Results show that insect-induced reductions in canopy interception, transpiration, and snow pack are largely mitigated by heightened ground evaporation and ablation, adding to the growing number of studies citing damping of MPB hydrologic signal at large scales.

Scale dependent parameterization in integrated hydrologic modeling The highly instrumented Wüstebach catchment in Germany allows the unique opportunity to explore the application of the information entropy concept in subsurface parameterization of three dimensional hydrological models. Results suggest that amplifying soil hydraulic conductivity in regions where aggregation of observations at model scale leads to loss of topographic information content may increase model performance, an important finding for high-resolution, large-scale physically based modeling that requires detailed subsurface parameterization.

Moisture dependent irrigation and its feedbacks with integrated hydrology In this example, ParFlow was used in conjunction with a novel linear optimization water allocation module to evaluate the impact of groundwater-surface water interactions on moisture dependent irrigation in the Little Washita River Basin, Oklahoma.