Evaluation of crop water productivity under sprinkler irrigation regime using a distributed agro-hydrological model in an irrigation district of China

Irrigation is essential for agriculture in the Hetao Irrigation District (HID), which is one of the important food production areas in China. Surface irrigation is main irrigation method, and the efficiency of irrigation water usage is very low. With the development of economics and the reduction of the water diversion from the Yellow River for agriculture, it is crucial to improve water productivity (WP) by trying to adopt modern irrigation method, such as sprinkler irrigation. In this study, a SWAP-WOFOST agro-hydrological model was calibrated and validated, and then used to simulate crop yields and WPs in the distributed manner under the scheduled sprinkler and surface irrigation regimes during 2000-2010 in the HID. The cropping pattern was adjusted further by quantitatively comparing the WPs of the three main crops. The results indicated that compared with the surface irrigation scenario, the annual average yields of spring wheat, spring maize, and sunflower were improved by 16.9%, 8.0%, and 11.4%, respectively, and the annual average WPs were increased by 7.9%, 5.0%, and 14.1%, respectively, after zoning in the sprinkler irrigation scenario. The corresponding multiyear (2000-2010) average required field irrigation amount for the whole cultivated lands would reduce about 4.09 × 108 m3 per year. At the same time, the groundwater contribution to crop water consumption became more, which did not cause groundwater depth sustainable decline during 2000-2010. Therefore, the improvement of irrigation method and the adjustment of cropping pattern could contribute to more sustainable food production and saving agricultural water usage in the HID.