河套灌区地下水时空变化趋势成因分析

Cause Analysis of Temporal and Spatial Variation of Groundwater Level in Hetao Irrigation Area

内蒙古河套灌区降水稀少,蒸发强烈,灌区地下水埋深不仅决定了区域水量平衡、水盐平衡、水热平衡,还将对区域生态系统产生重大影响。通过收集整理内蒙古河套灌区216眼观测井2003—2013年逐月地下水埋深观测资料,采用变异函数分析方法,并借助Arc GIS等手段,建立数学模型,研究了灌区地下水埋深在年内和年际的演变规律和空间变异特性;通过春灌、秋浇等典型灌溉期的水量平衡分析,揭示了地下水位变化的主要影响因素和物理机制;根据灌区自然地理特点、灌水习惯、可能的节水措施,拟定了3种节水模式,预测了不同模式下的地下水位变化幅度,结果表明,渠系水利用系数提高到国家标准0.55时,灌区的地下水埋深将比2013年的2.05 m增大0.26 m,达到2.31 m。

Hetao irrigation area in Inner Mongolia has the nature condition of the scarce rainfall and the strong evaporation. The depth of the groundw-ater in Hetao irrigation area not only deter^mines the regional water balance, water-salt balance and water-heat balance, but also has a significant impact on the regional ecosystem. The variation function analysis method and ArcGIS were applied to establish a mathematical analysis model wdth the year 2003-2013 collected from the 216 observation wells in Hetao irrigation area. Through the model, a evolution and spatial variability of groundwater depth in the irrigation area were studied at interannual scale and annual scale. The study on water balance during typical irrigation periods like spring irrigation and autumn irrigation revealed the main influence factors and physical mechanism of groundwater level change. Based on the characteristics of natural geography, the irrigation habits and possible water saving measures, threewater-saving modes were proposed to predict the groundwater level variation range under different modes, and to provide decisions based on water-saving measures which could also prevent the ecosystem degradation caused by the change of the groundwater level.