|Fausey, Norman - Norm|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Abstract Only
Publication Acceptance Date: 7/13/1998
Publication Date: N/A
Technical Abstract: Methods of simulating water flow paths in the near surface water table, impacted by subsurface drainage, were compared. The Agricultural Drainage and Pesticide Transport (ADAPT) model estimates daily subsurface drainage volumes using a version of the Hooghoudt equation. This requires that some method be employed to redistribute water with the saturated profile and between profile layers. Since this model has pesticide and nutrient transport components, it is important to make close approximations of water transport within the soil layers. Subsurface drainage complicates the issue by affecting the flow paths throughout the effective permeable profile. Standard two dimensional flow-net theory could not be used because ADAPT models the water table in one dimension. Hooghoudt's original drainage equation was used to partition drainage flow into two parts. The first part applies to flow through the zone above the drain and the second part accounts for flow which passes through the zone extending below the drain to the restrictive layer. This flow partition method was found to be adequate when compared to simulations with the finite element model SWMS_2D. When integrated into the ADAPT model (version 5.0), this method also improved the nitrate mass prediction in subsurface drain flow on a silty clay soil in north eastern Ohio. Further improvement was made to the model's nitrate prediction by a calibration of denitrification parameters.