Proper predictions of the water fate in agricultural lands: Indispensable condition for better crop water requirements estimates

This study proposes a new approach to employ the hydrology-based predictions of the water fate, rather than empirical ones, to estimate crop water requirements (CWRs) in artificially-drained agricultural lands. The study area comprises a 12 ha-wheat-land that locates in the lower reaches of the Yangtze River, China, for the growing season of 2018–2019. Despite there was almost no need for irrigation in the study area due to the amble rainfall; the empirical prediction of the water fate caused overestimations in CWRs (30840 m3). Under the same data of evapotranspiration and precipitation, the new approach enhanced CWRs estimates (12750 m3), and this is due to the well-known accuracy of hydrology-based approaches in predicting the water fate. In addition, the water fate in the study area was hydrological simulated and predicted under some scenarios of field conditions and management practices, and the new approach was applied to estimate CWRs under these scenarios. It was revealed that changes in the water fate affected much CWRs and caused an increase (up to 80%), compared to the estimated value under baseline conditions. Therefore, the accurate prediction of the water fate is indispensable for better CWRs estimates along with better utilization of available water resources. In addition, the new approach presented in this study can be applied to estimate future CWRs in artificially drained lands, along with the assessment of various impacts of many field conditions and management practices on CWRs.