Modified Model for Simulating Hydrologic Processes for Plastic Mulch Production Systems

AbstractA lumped hydrologic model (ACRU2K.1), developed from ACRU2000, was extended and evaluated to simulate water dynamics in a plastic mulch bedded system for vegetable production under high water table environments. The updated model (ACRU2K.2) and ACRU2K.1 were calibrated using data collected during the fall 2005 and spring 2006 crop seasons of a field study for a vegetable production system in south Florida. Both model versions were evaluated using data from the fall 2006 crop season. Graphical and statistical methods were applied to evaluate and compare the performance of ACRU2K.1 and ACRU2K.2 using observed and simulated water table depths (WTD). Graphical analyses showed no added advantage in using ACRU2K.2 with its new irrigation process. However, the introduction of a drainage process for ACRU2K.2 showed some improvement over ACRU2K.1 in simulating changes in the water table. For the calibration period, Nash-Sutcliffe coefficient (NS) values for ACRU2K.1 and ACRU2K.2 were 0.73 and 0.65, respectively. However, for the evaluation period NS values for ACRU2K.1 and ACRU2K.2 were −0.60 and −0.67, respectively. In general, ACRU2K.1 and ACRU2K.2 underperformed when simulating the WTD for plastic mulch bedded systems under high water table environments. This was the result of ACRU2000’s inability to respond correctly to sharp water table fluctuations (within 12 h) and is a fundamental limitation in its hydrological response time.