Repository logo

Engineering Faculty Research, Publications and Presentations

Permanent URI for this communityhttps://hdl.handle.net/10222/35352

Browse

Browsing Engineering Faculty Research, Publications and Presentations by Issue Date

Filter results by year or month
Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen 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.
  • Thumbnail Image
    ItemOpen 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.
  • Thumbnail Image
    ItemOpen Access
    Modification of the biophysical water function to predict the change in soil mineral nitrogen concentration resulting from concurrent mineralization and denitrification
    (2012-08) Georgallas, Alex; Dessureault-Rompre, Jacynthe; Zebarth, Bernie J.; Burton, David L.; Drury, Craig F.; Grant, Cynthia A.
    Georgallas, A., Dessureault-Rompre, J., Zebarth, B. J., Burton, D. L., Drury, C. F. and Grant, C. A. 2012. Modification of the biophysical water function to predict the change in soil mineral nitrogen concentration resulting from concurrent mineralization and denitrification. Can. J. Soil Sci. 92: 695-710. Uncertainty in soil N supply is an important limitation in making crop fertilizer N recommendations. This study modified a biophysical water function developed to predict net soil N mineralization, making it possible to consider how both N mineralization and denitrification processes affect the rate of soil mineral N accumulation. Data were from a published experiment measuring changes in soil mineral N concentration in five soils of varying texture (loamy sand to clay loam) incubated for 3 mo with or without addition of red clover residue and at two levels of compaction. The biophysical water function was effective in fitting the relationship between scaled change in the rate of soil mineral N accumulation (Delta SMN) and scaled water-filled pore space (WFPSs) across soils and treatments provided that WFPSs = 1 was set to the water content at which the transition from mineralization to denitrification occurs. The water content at WFPSs = 1 varied with soil type, but not residue addition or compaction treatments, and was closely related to clay content. The k(D), parameter, which controls the denitrification term of the function, was influenced by soil type, whereas legume residue application had no significant effect on the k(D) parameter despite a twofold increase in net N mineralization. The modified biophysical water function holds promise for improving estimates of soil N supply because it can predict changes in Delta SMN in response to N mineralization and denitrification processes across a wide range of soil water contents.