Correlation among farmland water consumption, grain yield and groundwater dynamics in the Hebei Plain

Farmland water consumption accounts for most of the groundwater consumption in the Hebei Plain. Research on the interaction mechanism of farmland water consumption, groundwater dynamics and grain production could provide critical evidence for water-saving agriculture. Based on Hebei Province economic statistical data, groundwater exploitation data, groundwater level data and conventional meteorological data for 1981?2010, this paper analyzed the changes in farmland water consumption, grain production, precipitation and groundwater level in the Hebei Plain in the recent 30 years. Their correlation was also discussed. The results showed that in the past 30 years, the Hebei Plain consumed 722.4 km³ of water for agriculture, produced 5.9×10⁸ tons of grain and exploited 440 km³ of groundwater (330 km³ of which was used for agricultural irrigation). This led to groundwater level decline of 11.5 m over the period. In general, farmland water consumption and grain yield in the Hebei Plain increased yearly while groundwater level declined against decreasing exploitation trends since 2000. There was a close correlation among farmland water consumption, groundwater exploitation, groundwater depth and grain yield. In the study area producing 1 ton of grain required 1 224.4 m³ of water (including 597.1 m³ of groundwater). Also for every 1 km³ of groundwater exploitation, groundwater level dropped by 0.03 m. Over-exploitation was the direct cause of groundwater level loss in the plain. This was because of insufficient precipitation to replenish the groundwater in volumes commensurate to exploitation. Although groundwater exploitation in the Hebei Plain slowed down since the beginning of this century, groundwater level still continued to decline. Therefore, the further development of water-saving agriculture was necessary to improve the efficiency of irrigation and to promote sustainable development of agriculture in the Hebei Plain.