中国典型地区地下水位对环境的控制作用及阈值研究

研究采用理论分析和实践成果相结合、区域宏观分析与典型地区深入剖析相结合的研究方法,从地下水不合理开发利用引起的环境问题出发,选取华北地区、西北地区以及沿海地区作为典型区,分析地下水位对环境的控制作用,提出了具有针对性的地下水位控制阈值。华北平原有利于山前调蓄的地下水位埋深为10m、中东部平原浅层控制土壤盐渍化水位埋深为2~3 m、防止地裂缝的水位埋深为7 m、深层控制地面沉降水位埋深为50 m、浅埋岩溶区地下水位应控制在岩溶含水层上覆的松散岩类的底板高程(2 m)之上;西北地区控制天然植被衰败的地下水位埋深为2.0~4.5 m和人工绿洲灌溉期控制土壤盐渍化的地下水位埋深为1.2~1.5 m,非灌溉期中冻结期地下水位埋深1.3~1.5 m,冻融期为2.2~2.7 m;沿海地区防止海水入侵的地下水位阈值应控制在漏斗中心水位高程-5~-6 m,最大不超过-8 m。上述地下水位控制阈值的确定,为实施地下水总量控制和水位控制管理提供了科学依据。

Control function of groundwater table on the environment of typical areas in China and the study of thresholds

Based on the analysis of the status of groundwater development and utilization in China and the corresponding environmental problems,we selected North China Plain,the northwest inland and coastal areas as representation areas to analyze the control actions of groundwater table on environment,and put forward the idiographic thresholds of groundwater tables by the method of combination of theoretical analysis with practical achievements and combining the regional macro analysis with detailed analysis of the representative area.In North China Plain,the groundwater depth for regulating functions in the piedmont alluvial plain is 10 m.In the middle-eastern plain,the groundwater depth in shallow aquifer that prevents the soil salinification is 2-3 m,and that prevents the ground fissure is 7 m;the groundwater depth of confined aquifer that avoids the broad area land subsidence is 50 m;in the shallow karst district,the groundwater table should be above the top of karst aquifer(2 m).In the northwest inland,the groundwater depth in natural plant community that prevents nature vegetation decline is 2.0-4.5 m,and in artificial oasis that prevents the soil salinification is 1.2-1.5 m in irrigation time,1.3-1.5 m in defrosting time and 2.2-2.7 m in frozen time.In coastal areas,the groundwater table preventing the seawater intrusion is-5—6 m in the center head of groundwater depression cone and the maximum groundwater table is-8 m.The above-mentioned determinations of the thresholds of groundwater tables may provide a scientific basis for groundwater management.