西辽河平原地下水失衡及其与土地利用的互馈关系

Groundwater imbalance and its mutual feedback relationship with land use in West Liaohe Plain

西辽河平原是我国北方重要的生态屏障,但是生态环境脆弱。2004年以来农田灌溉用水增加,地下水水位持续下降。为查明区域地下水失衡、生态效应及其影响因素,开展了西辽河平原地下水水位统测和长期监测,采用空间相关性分析、水均衡分析、土地利用转移矩阵、对地下水水位变化贡献度分析等方法,分析了区域地下水均衡状况及其与土地利用的互馈关系。结果表明:西辽河平原2020年地下水水位比2004年平均下降2.23 m,地下水储存量年均减少10.90×10^(8) m^(3);平原中部农业集中灌溉区地下水水位下降幅度较大,尤其通辽科尔沁区地下水水位下降最为明显;西辽河平原地下水开采量对地下水水位下降的贡献度为33%,科尔沁区超过50%;地下水水位下降区水位埋深从4.71 m下降至8.34 m,导致草地退化,面积减少,覆盖度下降;西辽河平原地下水可持续开采量为24.28×10^(8) m^(3)/a。用于农业灌溉的地下水开采量增大是造成地下水水位下降的主要原因,为防止地下水水位持续下降,提出了提高节水灌溉能力,调整种植结构、引入外源水及压缩地下水开采量等综合治理建议。该研究成果可为区域农业种植规划、地下水管理与保护提供技术支撑。

The West Liaohe Plain(WLP)is an important ecological barrier in northern China.Due to the increase in irrigation water since 2004,the groundwater level has continued to decline in the WLP.To investigate the regional groundwater imbalance,ecological effects,and their influence factors,the regional groundwater balance and its mutual feedback relationship with land use in the WLP were analyzed by using the methods of groundwater level measurement and long-term monitoring,the spatial correlation analysis,water balance analysis,land use transfer matrix,and contribution to groundwater level change.The results show that the groundwater level in the WLP in 2020 decreased by an average of 2.23 m compared with that in 2004,with a groundwater storage decrease rate of 10.90×10^(8) m^(3) per year(average value).The large decline of groundwater level occurs in the centralized irrigated area in the central part,in particular in the Keerqin District,Tongliao City.The contribution of groundwater extraction to the groundwater level decrease is 33%in the WLP and more than 50%in the Keerqin district.In the area with a groundwater level decrease,the groundwater level depth increases from 4.71 m to 8.34 m,resulting in grassland degradation and coverage reduction.The sustainable extraction of groundwater in WLP is 24.28×10^(8) m^(3)/a.Increased groundwater extraction for agricultural irrigation is the main reason for the groundwater level decrease.To prevent the continuous groundwater level decline,comprehensive management methods,such as improving the capacity of water-saving irrigation,adjusting the planting structure,introducing water from the outer watershed,and reducing the amount of groundwater extraction are suggested.This study can provide technical support for regional agricultural cultivation planning and groundwater management and protection.