长江流域地下水资源特征与开发利用现状

Groundwater resources in the Yangtze River Basin and its current development and utilization

为提升对长江流域水文地质和地下水资源的认知程度,突破以往单独从地表水或地下水角度进行评价的局限性,长江流域水文地质调查工程以地球系统科学理论和水循环理论为指导,充分考虑地表水与地下水的转化关系,将水文地质单元和地表水流域有机结合,划分长江流域地下水评价单元,建立典型地下水资源评价模型,开展了新一轮长江流域地下水资源评价。评价结果表明:(1)长江流域水循环要素时空分布不均,降水以中游最多,并由东南向西北递减;地表径流主要集中在夏季,且长江北岸比南岸集中程度更高;蒸散发量总体上呈现东部高于西部的特征,最大值集中在长江中游一带;长江流域地下水位总体保持稳定,丰枯季水位变化总体不大,一般小于2 m;长三角超采区的地下水漏斗面积已明显减小,相关环境地质问题得到了有效控制。(2)2020年长江流域的地下水资源总量2421.70亿m^(3)/a,其中山丘区地下水资源量2092.79亿m^(3)/a,平原区地下水资源量331.35亿m^(3)/a;地下水储存量较2019年整体略有增加趋势,其中四川盆地最为明显,共增加23.72亿m^(3)。(3)长江流域的水质上游优于下游,优质地下水主要分布在赣南地区和大别山南麓一带,部分地区水质较差的主要原因是原生劣质水的广泛分布。长江流域地下水开发利用水平整体很低,局部地区由于过往不合理的开发所引发的环境地质问题已得到缓解,岩溶塌陷、地面沉降等问题得到了较好控制。建议适当开发利用赣南地区和大别山南麓一带优质的基岩裂隙水。

In order to improve the cognition of hydrogeology and groundwater resources in the Yangtze River Basin and break through the limitations of previous evaluation from the point of view of surface water or groundwater,the hydrogeology survey project in the Yangtze River Basin was guided by the earth system science theory and water cycle theory.Based on the full consideration of the transformation relationship between surface water and groundwater,hydrogeology unit and surface water basin were organically combined to divide groundwater evaluation units in the Yangtze River Basin.A new round of groundwater resource evaluation in the Yangtze River basin was carried out through the establishment of typical groundwater resource evaluation model.The evaluation results show that the spatial and temporal distribution of water cycle elements in the Yangtze River basin is uneven,with the highest precipitation in the middle reaches and decreasing from southeast to northwest.Surface runoff is mainly concentrated in summer,the north bank is higher than the south bank in summer concentration surface runoff.Evapotranspiration is generally higher in the east than in the west,and the maximum value is concentrated in the middle reaches of the Yangtze River.The groundwater level in the Yangtze River basin remains stable on the whole,and the water level changes little in the peak and dry seasons,generally less than 2 m.The area of groundwater funnel in the Yangtze River Delta over-exploitation area has been significantly reduced,and the related environmental geological problems have been effectively controlled.In 2020,the total groundwater resources in the Yangtze River Basin was 242.170 billion m^(3)/a,including 209.279 billion m^(3)/a in hilly areas and 33.135 billion m^(3)/a in plain areas.Compared with 2019,the groundwater storage increased slightly,especially in Sichuan Basin,with a total increase of 2.372 billion m^(3).The water quality in the upper reaches of the Yangtze River basin is better than that in the lower reaches,and the high-quality groundwater is mainly distributed in southern Jiangxi and the western foothills of Dabie Mountains.The main reason for poor water quality in some areas is the widespread distribution of primary inferior water.The development and utilization level of groundwater in the Yangtze River Basin is very low as a whole.The environmental geological problems caused by unreasonable development in some areas have been greatly solved,and karst collapse and land subsidence have been well controlled.It is suggested that high-quality bedrock fissure water should be properly developed and utilized in southern Jiangxi and south Dabie Mountains.