Prediction of crop yield, water consumption and water use efficiency with a SVAT-crop growth model using remotely sensed data on the North China Plain

A process-based crop growth model is developed to predict regional crop yield, water consumption and water use efficiency (WUE) using remotely sensed data for a portion of Hebei province (88 779 km(2)), most of which is located on the North China Plain (NCP). Model inputs consist of Geographic Information System (GIS) maps of land use, Digital Elevation Model (DEM), soil texture, crop canopy leaf area index (LAI) which is retrieved from the 10-day maximum composite National Oceanic and Atmospheric Administration (NOAA)-Advanced Very High Resolution Radiometer (AVHRR) data, and daily interpolated meteorological variables. The model is run at 92 367 30" x 30". resolution grids at an hourly time-step for energy balance and daily time-step for crop growth simulation. Simulated winter wheat and summer maize yields in 1992 and 1993 are compared with both the point samples and the county-level census data. For the 108 counties, the root mean square error (relative deviation) is 1124 kg ha(-1) (23%) for winter wheat and 1359 kg ha(-1) (33%) for summer maize, respectively. Spatial patterns of simulated crop yield and water use efficiency are strongly influenced by irrigated/rainfed conditions. The modelled grain yield for irrigated winter wheat ranges from 3900 to 7200 kg ha(-1), which is significantly larger than when only rainfed, 100-2600 kg ha(-1). The modelled grain yield for irrigated maize ranges from 5800 to 8600 kg ha(-1), which is significantly larger than when only rainfed, 1400-4800 kg ha(-1). This suggests that the potential exists to increase yield in this region, if sufficient irrigation water is supplied. However, given the over allocation of limited surface water, an increase in irrigation is unlikely, and increasing importance will be placed on maximizing regional WUE over the NCP. The water consumption (defined here as modelled evapotranspiration (ET)) for winter wheat ranges from 330 to 500 and 70 to 280 mm for irrigated and rainfed conditions, respectively. The modelled ET for irrigated maize ranges from 350 to 520, and 140 to 350 mm for rainfed conditions. The simulated WUE ranges from 12.25 to 15.75 kg ha(-1) mm(-1) for irrigated winter wheat and from 0.5 to 8.25 kg ha(-1) mm(-1) in rainfed areas. The simulated WUE ranges from 11 to 19.25 kg ha(-1) mm(-1) for irrigated maize and from 5 to 11 kg ha(-1) mm(-1) in rainfed areas. These, together with the results of simulated crop yields, are comparable with previous studies in the NCP, other parts of China, and internationally, indicating the potential to apply this model to other agricultural regions. This study implicates a new view for regional agricultural and water resources management by assessing regional crop yield, water consumption and WUE consistently based on modelling biophysical processes with the aid of remote sensing. (c) 2004 Elsevier B.V. All rights reserved.EcologySCI(E)EI95REVIEW2-3301-32218