Water table dynamics between two adjacent subsurface drainage laterals in a paddy field: A newly improved analytical solution

Abstract

Installation of subsurface drainage systems in paddy fields is crucial to achieve the feasibility of year‐round cropping and high productivity and to create more conducive working conditions for the use of farm machinery. Therefore, three subsurface drainage systems were installed in a paddy field located in northern Iran to control the water table (WT) during the rainy seasons. To predict the WT between subsurface drainage systems in the field, an analytical solution of two‐dimensional transient saturated flow was presented using the Bear equation. In the next step, a modified procedure was developed to separately involve the vertical head due to the existence of clayey and layered soils in the studied field. The results of the solutions were compared with the collected field data. The obtained results for the WT profile indicated that the modified procedure had a better agreement with the field data (9%–13% differences) in comparison with the conventional two‐dimensional solution (23%–75% differences). This revealed that considering the vertical head in the media cannot be ignored in analytical or numerical simulations of WT dynamics. As a concluding result, the modified procedure was found to be more efficient in paddy field drainage design.