河北平原农田耗水与地下水动态及粮食生产相互关系分析

农田耗水是河北平原地下水资源消耗的主体,农田耗水与地下水动态、粮食生产互制机理研究可为农业节水提供重要依据。基于1981—2010年河北省经济统计年鉴、地下水开采量与地下水位、常规气象等数据,分析了河北平原近30年来农田耗水、粮食产量、降水量、地下水等动态变化特征,揭示了它们之间的相互响应关系。结果表明,近30年来,河北平原农田耗水总量约722.4 km3,生产粮食约5.9×108 t,开采地下水约440 km3(其中约330 km3用于农田灌溉),地下水位共下降约11.5 m;河北平原农田耗水与粮食产量总体呈逐年上升趋势,尽管2000年以来地下水开采量有所减少,但地下水位一直持续下降;农田耗水与地下水开采量、地下水埋深、粮食产量相互之间关系密切,每生产1 t粮食所消耗的水资源约1 224.4 m3(包括地下水597.1 m3),而地下水开采量每增加1 km3,河北平原地下水位实际下沉约0.03 m;农田耗水、地下水埋深均与年降雨量无明显相关性,由于降水入渗、灌溉渗漏不足以弥补开采的地下水,超采是引起河北平原地下水位持续下降的直接原因。因此,进一步发展节水农业、提高灌溉效率是促进河北平原农业可持续发展的必然选择。

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.