title: Modeling contribution of shallow groundwater to evapotranspiration and yield of maize in an arid area.
abstract: Capillary rise from shallow groundwater can decrease the need for irrigation water. However, simple techniques do not exist to quantify the contribution of capillary flux to crop water use. In this study we develop the Agricultural Water Productivity Model for Shallow Groundwater (AWPM-SG) for calculating capillary fluxes from shallow groundwater using readily available data. The model combines an analytical solution of upward flux from groundwater with the EPIC crop growth model. AWPM-SG was calibrated and validated with 2-year lysimetric experiment with maize. Predicted soil moisture, groundwater depth and leaf area index agreed with the observations. To investigate the response of model, various scenarios were run in which the irrigation amount and groundwater depth were varied. Simulations shows that at groundwater depth of 1 m capillary upward supplied 41% of the evapotranspiration. This reduced to 6% at groundwater depth of 2 m. The yield per unit water consumed (water productivity) was nearly constant for 2.3 kg/m3. The yield per unit water applied (irrigation water productivity) increased with decreasing irrigation water because capillary rise made up in part for the lack of irrigation water. Consequently, using AWPM-SG in irrigation scheduling will be beneficial to save more water in areas with shallow groundwater.
authors.affiliation: Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, P.R. China.|Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Gao
authors.affiliation: Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, P.R. China.
authors.forename: Zailin
authors.initials: Z
authors.lastname: Huo
authors.affiliation: Inner Mongolia Agricultural University, Hohhot, 010018, China.
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Qu
authors.affiliation: Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, P.R. China.
authors.forename: Xu
authors.initials: X
authors.lastname: Xu
authors.affiliation: Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, P.R. China.
authors.forename: Guanhua
authors.initials: G
authors.lastname: Huang
authors.affiliation: Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA.
authors.forename: Tammo S
authors.initials: TS
authors.lastname: Steenhuis
mesh_terms: D057914:Agricultural Irrigation; D003889:Desert Climate; D060587:Groundwater; D008954:Models, Biological; D003313:Zea mays / Q000502:physiology*