Modelling irrigated maize with a combination of coupled-model simulation and uncertainty analysis, in the northwest of China

摘要

The hydrologic model HYDRUS-1-D and the crop growth model WOFOST are coupledto efficiently manage water resources in agriculture and improve theprediction of crop production. The results of the coupled model arevalidated by experimental studies of irrigated-maize done in the middlereaches of northwest China's Heihe River, a semi-arid to arid region. Goodagreement is achieved between the simulated evapotranspiration, soilmoisture and crop production and their respective field measurements madeunder current maize irrigation and fertilization. Based on the calibratedmodel, the scenario analysis reveals that the most optimal amount ofirrigation is 500–600 mm in this region. However, for regions withoutdetailed observation, the results of the numerical simulation can beunreliable for irrigation decision making owing to the shortage ofcalibrated model boundary conditions and parameters. So, we develop a methodof combining model ensemble simulations and uncertainty/sensitivity analysisto speculate the probability of crop production. In our studies, theuncertainty analysis is used to reveal the risk of facing a loss of cropproduction as irrigation decreases. The global sensitivity analysis is usedto test the coupled model and further quantitatively analyse the impact ofthe uncertainty of coupled model parameters and environmental scenarios oncrop production. This method can be used for estimation in regions with noor reduced data availability.