A study of achieving groundwater equilibrium and stable winter wheat yield simultaneously

The piedmont plain of Taihang Mountains in Hebei Province is the most severe shallow groundwater depletion region in China, as well as an important growing area of winter wheat with high quality. How to achieve the goals of shallow groundwater equilibrium and stable winter wheat yield simultaneously has become a key issue for the water management and agricultural production of this well-irrigated plain. The simulated results based on a distributed hydrological model showed that to satisfy the constraint of stopping shallow groundwater drawdown, the average minimal reduction in winter wheat yield would be over 40%. It was difficult to maintain the current winter wheat production only rely on the shallow groundwater resource carrying capacity. The middle route of South-to-North Water Diversion (SNWD) project that goes through the piedmont plain of Taihang Mountains in Hebei Province provides a potential source of irrigation water to this region. In this context, we proposed a limited irrigation scheme by applying two rounds of irrigation – one round using shallow groundwater and one round using SNWD water –for the winter wheat. The estimated results showed that under this limited irrigation scheme, it would be expected to basically realize shallow groundwater equilibrium as well as maintain the winter wheat yield stable. It should be noted that approximately 8.6×10⁸ m³ of SNWD water would be required every year as the irrigation source, and the irrigation cost would increase by 562.5～1282.5 yuan/hm² at least. This alternative limited irrigation scheme could serve as a quantitative reference for this shallow groundwater overexploited region to explore the trade-off between crop production and water saving.