Abstract
Abstract. Rapid population growth is increasing pressure on the world water resources. Agriculture will require crops to be grown with less water. This is especially the case for the closed Yellow River basin, necessitating a better understanding of the fate of irrigation water in the soil. In this paper, we report on a field experiment and develop a physically based model for the shallow groundwater in the Hetao irrigation district in Inner Mongolia, in the arid middle reaches of the Yellow River. Unlike other approaches, this model recognizes that field capacity is reached when the matric potential is equal to the height above the groundwater table and not by a limiting soil conductivity. The field experiment was carried out in 2016 and 2017. Daily moisture contents at five depths in the top 90 cm and groundwater table depths were measured in two fields with a corn crop. The data collected were used for model calibration and validation. The calibration and validation results show that the model-simulated soil moisture and groundwater depth fitted well. The model can be used in areas with shallow groundwater to optimize irrigation water use and minimize tailwater losses.
Highlights
With global climate change and increasing human population, much of the world is facing substantial water shortage (Alcamo et al, 2007)
A novel surrogate vadose zone model for an irrigated area with a shallow aquifer was developed to simulate the fluctuation of groundwater depth and soil moisture during the crop growth stage in the shallow groundwater district
To validate and calibrate the surrogate model we carried out a 2year field experiment in the Hetao irrigation district in upper Mongolia with groundwater close to the surface
Summary
With global climate change and increasing human population, much of the world is facing substantial water shortage (Alcamo et al, 2007). When averaged over the whole country, available water per capita is at the water stress threshold of 1700 m3 yr−1 (Falkenmark, 1989; Brown and Matlock, 2011). It is even less in the arid to semi-arid Yellow River basin that produces 33 % of the total agricultural production in China. To overcome water shortages in the Yellow River basin, crops are irrigated from surface water and groundwater. This irrigation has directly changed the hydrology of the basin. In arid Inner Mongolia, along the Yellow River, the once-deep groundwater is within 3 m of the soil surface in the large irrigation projects such as the Hetao irrigation district because of downward percolation of the excess irrigation water that has been applied
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