Water use by a groundwater dependent maize in a semi-arid region of Inner Mongolia: evapotranspiration partitioning and capillary rise

• Autor(a) principal: Wu, Yao
• Data de Publicação: 2015
• Outros Autores: Liu, Tingxi, Paredes, Paula, Duan, Limin, Pereira, L.S.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/14066
• topic: SIMDualKc model; groundwater contribution; dual crop coefficients; crop transpiration; soil evaporation; groundwater dependent ecosystems

tThis study aimed at assessing the soil water balance, groundwater contribution, crop transpiration andsoil evaporation of a rainfed maize crop in Horqin sandy area, north-eastern Inner Mongolia, China.Two years of field data from the Agula site were used, 2008 with relatively high rainfall (363 mm) andhigh water table, and 2009 with low rainfall (125 mm) and lower water table. The SIMDualKc waterbalance model was calibrated with observed soil water content data of 2008 and validated with dataof 2009. The model uses the dual crop coefficient approach for evapotranspiration (ET) partitioning,and parametric functions for computing capillary rise. The respective modelling results show that thegroundwater contribution represented ca. 50% of crop ET in both years. Estimation errors are small,with root mean square errors of 0.007 and 0.008 cm3cm−3respectively in 2008 and 2009. The Nash andSutcliffe modelling efficiency were high, 0.93 in both years, which indicates a low variance of residuals.The calibrated basal crop coefficient Kcb mid= 0.95 denotes a low density of the crop because it is muchlower than common potential values. Soil evaporation was relatively low, 23% of ET in the wet year and17% in the dry year, because capillary rise does not contribute to soil evaporation but to roots extractiononly. Results show that capillary rise plays a main role in supplying the vegetation throughout the season,hence a strong dependence of vegetation upon groundwater.