冀中山前平原农业区浅层地下水位对连年少雨响应特征与机制

冀中山前平原农业区浅层地下水是当地农田灌溉的主要水源，已处于超采状态。依据冀中山前平原不同农业区长观孔浅层地下水位动态监测资料，对浅层地下水位响应连年降水偏枯的变化规律进行了研究。结果表明:降水连年偏枯（少雨）时段的春灌期大规模集中开采浅层地下水，是冀中山前平原农业区浅层地下水位不断下降的主要动因；春灌期农业区浅层地下水位降幅与前一年和当年1月到6月降水量密切相关；当年降水量小于当地多年平均降水量（528.4 mm）时，随着降水量减小，农业用水开采对浅层地下水位下降的影响增大；当年降水量大于当地多年平均降水量尤其大于620 mm时，农业用水开采对浅层地下水位下降的影响显著减弱；合理调控农业区浅层地下水开采强度是缓解冀中山前平原农业区浅层地下水超采情势的重要举措。

Response Characteristic and Mechanism of Shallow Groundwater Level on the Successive Years with Less Rainfall in the Agricultural Areas of the Central Hebei Piedmont Plain

Shallow groundwater, which is in over-exploitation, is the main water source of farm irrigation in the agricultural areas of the central Hebei piedmont plain. According to the dynamic monitoring data of shallow groundwater level from long-time observation hole in the different agricultural areas of the central Hebei piedmont plain, variable characteristics of shallow groundwater level response to the successive years with less rainfall were studied. The results show that large-scale and intensive shallow groundwater exploitation during spring irrigation periods of successive years with less rainfall mainly causes the continuous decline of shallow groundwater level in the agricultural areas of the central Hebei piedmont plain; the decline amplitude of shallow groundwater level during spring irrigation period is related closely with the precipitation from January to June of the previous year and the same year; when the annual precipitation is less than the local annual average precipitation (528.4 mm), the effect of agricultural water exploitation on the decline of shallow groundwater increases significantly with the decrease of precipitation; when the annual precipitation is more than the local annual average precipitation, even more than 630 mm, the effect of agricultural water exploitation on the decline of shallow groundwater decreases significantly; adjusting and controlling rationally the exploitation intensity of shallow groundwater in the agricultural areas is important for improving the sustainable utilization of shallow groundwater in the agricultural areas of the central Hebei piedmont plain.