黄淮海平原地下水危机下的耕地资源可持续利用

Cropland Sustainable Use Impacted by Groundwater Depletion in China's HHH Plains

研究目的:基于多数据源计算黄淮海平原地下水位平均下降速度,揭示该地区地下水快速下降机理,提出水资源限制下的耕地可持续利用对策。研究方法:根据收集的黄淮海平原266个地下水位下降速度样本点和5个典型城市地下水位长期监测点,由克里格插值得到区域地下水位平均下降速度,并采用空间分析的方法叠加2012年耕地分布图,分析不同地下水下降速度在9个子生态区对应的耕地分布情况。研究结果:1980年以来,黄淮海平原地下水以浅层0.46±0.37 m/年,深层1.14±0.58 m/年的速度下降,成为世界上面积最大的地下水漏斗区。造成地下水快速下降的主要原因是区域粮食增产和一年两熟种植制度下小麦播种面积的增加导致的大面积、高强度的井灌方式。根据地下水资源危机程度,将黄淮海平原划分为休养调整区、强度降低区、生态保护区和潜力提升区4个耕地利用调整区划。研究结论:黄淮海平原高集约高投入的耕地利用方式不可持续,在区域地下水危机的情况下,应降低超采区的耕地利用强度,同时提升潜力区的耕地生产潜力,实现耕地生产、生态质量协同提升,在保障粮食安全和生态安全的前提下实现耕地资源可持续利用。

The purpose of this study is to calculate the average groundwater depletion rate of China＇s Huang-Huai- Hal （HHH） plains, explore the driving force of the groundwater depletion and provide a decision basis for policy making to regulate the farmland use at the limit of exhausted water resource. Based on previous collection 266 groundwater depletion rate samples and 5 long-term monitoring cities, Kriging interpolations with ArcGIS are used to convert data into the magnitude of water depletion. Furthermore, spatial matching with ArcGIS is used to overlay the groundwater depletion rate layer and cropland distribution layer within nine major agro-ecological regions. The results indicate that the groundwater in HHH plains is being depleted at a mean rate of 0.46 ±0.37 m yr-1 for the shallow groundwater, and 1.14 ± 0.58 m yr-1 for deep groundwater. It has become the severest depression zone in the world since the 1980s. The severity of groundwater depletion is attributed to dramatic increase in crop yields and total production in the HHH driven by intensive irrigation. According to the aquifer depletion extent, the HHH is grouped into four adjusting zones, i.e., agricultural-adjust zone, intensity-reduce zone, ecology-sustain zone, and potential-use zone. The paper concludes that the ＂fallowing land and exploit potentialities＂ should be the target of building farmland ecological and food security system. The virtual research provides a useful reference for the future farmland sustainable use policy making in China.