Havard, Peter
Permanent URI for this collectionhttps://hdl.handle.net/10222/38549
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Item Open Access Linkflow, a Water-Flow Computer-Model for Water-Table Management .1. Model Development(1995-03) Havard, P. L.; Prasher, S. O.; Bonnell, R. B.; Madani, A.A computer simulation model, LINKFLOW, was developed to calculate the movement of water during various water table management practices, namely subsurface drainage, controlled drainage, and subirrigation. The model can simulate water movement through a heterogeneous and anisotropic saturated soil and includes an unsaturated flow component with a zone of water extraction by plant roots. The computer program links a newly developed one-dimensional unsaturated water flow model to an existing but modified three-dimensional saturated water flow model, MODFLOW. The water movement is simulated for a region of the field, and results obtained define water conditions in the root zone for a wide range of soil, topography, drain location, and weather conditions. LINKFLOW is unique among soil waterflow models because of the following features: I) it can simulate soil-water conditions beneath a crop on land with varying topography; 2) it can determine 3-D flows from drains in a heterogeneous, anisotropic soil; and 3) it can simulate the effects of different automated control strategies for subirrigation. Results can be presented in tabular format, contour map format, and/or a 3-D surface format to help understanding flow behavior of the system. A subirrigation case simulation is presented to illustrate just one example of the model's use in water table management studies. This article focuses on the development of the simulation model.Item Open Access LINKFLOW, a water flow computer model for water table management: Part 2. Model verification(1997-12) Havard, P. L.; Prasher, S. O.; Bonnell, R. B.; Madani, A.A computer simulation model, LINKFLOW, was developed (Havard et al., 1995) to simulate the movement of water during various water table management practices. This article described the validation of the linked saturated-unsaturated water flow model, LINKFLOW. The model was validated against published data on water table elevations during transient drainage. Simulation results were compared with measurements from field experimental plots. Results from the validation indicate a good comparison between simulated and measured values. Coefficients of variation for simulated and measured water table elevations were typically less than 15% for all water table management plots during the growing season. Verification showed that LINKFLOW could simulate the spatial influence of water table movement during various water management systems and account for soil property variation with depth and topography.