Assessing water productivity in the Hetao Irrigation District in Inner Mongolia by an agro-hydrological model

The Hetao Irrigation District (HID) is an important food production area, where irrigation is essential for agriculture. Because of water shortages, it is crucial to optimize the irrigation schedule and cropping structure to preserve the water resource and maintain sustainable crop production. In this study, a distributed Soil-Water-Atmosphere-Plant WOrld FOod STudies model was calibrated and validated, and then used to simulate yield and water productivity (WP) during 2000-2010 in the HID. Then, the suggested irrigation schedules and the cropping structure were analyzed by comparisons of yield and WP. The results showed that, compared with the basic scenario, the annual average yields of spring wheat, spring maize, and sunflower were improved by 17.3, 1.2 and 10.5%, respectively, and the crop WPs were increased by 9.5, 3.7 and 16.5%, respectively, after division in the suggested irrigation scenario. The corresponding multiyear (2000-2010) average field irrigation amount (irrigation amount x cultivated areas) that would be saved was 4.89 x 10(8) m(3). Although the capillary rise of groundwater was larger, the groundwater depth could not sustainably decline during 2000-2010. Therefore, the irrigation schedules and the cropping structure suggested in this study could contribute to more sustainable food production and reduced irrigation water usage in the HID.