冀中山前农业区地下水位强降弱升特征与机制
Sharp decline and sluggish rise of shallow groundwater level in the Central Hebei piedmont agricultural region
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摘要: 针对冀中山前平原农业区浅层地下水位不断下降问题,采用时间序列异变特征和趋势分析方法,基于小时级、自记监测的地下水位动态资料,通过农业区灌溉期、非灌溉期地下水位变化程度的差异特征及机制研究,结果表明:该平原农业区浅层地下水位变化在主灌溉期呈"cm/d"级(大于1.0 cm/d)下降、非灌溉期呈"mm/d"级(小于1.0 cm/d)上升的特征,这些特征与降水量、年内降水分配状况及其影响的农业开采强度密切相关。前期降水偏枯,灌溉期地下水位下降过程线和年内水位上升过程线的大部分位于当地多年地下水位变化趋势线之下;前期降水偏丰,位于趋势线之上。农业集中开采是地下水位"cm/d"级下降特征的动因,厚大包气带是地下水位"mm/d"级上升特征形成的重要条件。Abstract: In response to the constant decline of shallow groundwater level in the Central Hebei piedmont agricultural region, this paper monitored the hour-scale dynamic variation data of water levels and analyzed the difference of groundwater level changes during irrigation and non-irrigation periods by employing time-series variation feature and trend analysis method. Results indicate that the shallow groundwater level declines by more than 1.0 cm/d during irrigation period and rises by less than 1.0 cm/d during non-irrigation period, which is closely correlated with precipitation amount and distribution as well as agricultural exploitation intensity. For irrigation periods with low precipitation, the declining lines and rising lines are below the local average annual water level variation line, while for irrigation periods with abundant precipitation, they are above the local average annual water level variation line. Large-scale intense agricultural exploitation has led to the water level decline by the scale of cm/d, while the water level rise with the scale of mm/d is attributed to the local thick unsaturated zone(thicker than 15m).