The concentration and amounts of NO3-N and TN transported in surface, accelerated subsurface, and subsurface runoff and stream flow draining a 20 ha pasture watershed were measured over a period of 3 yr. A slight decrease and increase of NO3-N and particulate N concentrations, respectively, were obtained with increased flow of the runoff types and stream, due to dilution and increased sediment ...

[1] Current approaches for inverse modeling (IM) to estimate flow and transport properties in subsurface media implicitly assume that uncertainty in the input-output representation of the model arises from uncertainty in the parameter estimates. However, uncertainties in the modeling procedure stem not only from uncertainties in the parameter estimates, but also from measurement errors, from in...

The Subsurface Flow and Transport Team at the Los Alamos National Laboratory (LANL) has been involved in large scale projects including performance assessment of Yucca Mountain, Environmental Remediation of the Nevada Test Site, the LANL Groundwater Protection Program and geologic CO2 sequestration. Subsurface physics has ranged from single fluid/single phase fluid flow when simulating basin sc...

In the base grant project, Impact of Stream-Subsurface Exchange on Fine Sediment Dynamics in Streams funded through Drexel University, the objectives were to examine the complex interactions between high sediment loadings, downstream transport of suspended sediment, stream-subsurface exchange and siltation of stream beds. Results demonstrate that stream-subsurface exchange delivers suspended se...

[1] We conducted a detailed study of subsurface flow and water table response coupled with digital terrain analysis (DTA) of surface and subsurface features at the hillslope scale in Panola Mountain Research Watershed (PMRW), Georgia. Subsurface storm flow contributions of macropore and matrix flow in different sections along an artificial trench face were highly variable in terms of timing, pe...

Supraglacial channel networks link time varying melt production and meltwater routing on temperate glaciers. Such channel networks often include components of both surface transport in streams and subsurface porous flow through near-surface ice, firn or snowpack. Although subsurface transport if present will likely control network transport efficacy, it is the most poorly characterized componen...

[1] A distributed physically based model incorporating novel approaches for the representation of surface-subsurface processes and interactions is presented. A path-based description of surface flow across the drainage basin is used, with several options for identifying flow directions, for separating channel cells from hillslope cells, and for representing stream channel hydraulic geometry. La...

Benchmarking coupled surface-subsurface flow models becomes more important as they are increasingly used for operational purposes (e.g. in water management) and long-term analysis (e.g. in climate change research). For this reason we inter-compare the hydrogeological models HydroGeoSphere and OpenGeoSys and present results with emphasis on the parametrization of the surface-soil water coupling ...

Siyi Shao). Upper right: Carbonate minerals (white) filling fractures formed from mechanical response to chemical reactions in olivine-rich rocks (Courtesy of Peter Kelemen). Lower Right: Localized geochemical alteration of rock matrix due to fluid flow and reactions along fractures (Source of image unknown). Executive Summary From beneath the surface of the earth, we currently obtain about 80-...