Project Number: 5310-61000-014-01
Project Type: Specific Cooperative Agreement

Start Date: Sep 30, 2005
End Date: Jul 31, 2010

Objective:
The objective of this cooperative agreement is to develop and test computer software that may be used to predict the fate and transport of agricultural chemicals (salts, toxic trace elements, pathogenic microorganisms, pharmaceuticals) in the subsurface, and to test several parts of the software against experimental data.

Approach:
As part of this project, several new processes will be incorporated in the windows-based HYDRUS computer programs simulating water, heat and solute movement in soils and groundwater. Among these are (1) improved provisions for simulating three-dimensional transport problems, (2) preferential flow as modeled with alternative dual-permeability models, (3) multicomponent solute transport as applied to toxic trace elements, (4) an energy balance at the soil surface (using the Penman-Monteith or alternative methods), (5) overland flow to improve the design of surface irrigation systems, and (6) colloid and colloid-facilitated transport. The various features will be tested internally to ensure correct mathematical programming. Modeling results will be compared to selected data sets to ensure applicability to a variety of transport problems, and to identify strengths and weakenss of the conceptual formulations incorporated into the software. Closely related objectives of the project are to (a) develop or improve windows-based graphical interfaces of the 1D, 2D and 3D flow transport modules within the HYDRUS software, (b) use model abstraction techniques involving a hierarchy of process-based modules within HYDRUS to analyze a large experimental data set on water flow in a heterogeneous field soil, and (c) develop alternative pedotransfer functions for implementation in HYDRUS, and for application to the NASIS soil hydraulic database of the National Resources Conservation service (NRCS). Formerly 5310-61000-009-04S (JUN 07).