通过永定河渗漏补给地下水的适宜性评估研究

The suitability assessment of groundwater recharge by leakage of the Yongding River

受气候变化和人类活动等因素的综合影响,地下水超采和含水层水量亏空已成为备受关注的全球性问题。为了弥补含水层水量亏空和促进地下水资源涵养,已探索出多种人为干预地下水补给的措施,其中通过河道开展地下水人工补给由于具有明显优势而受到重视。已有实践表明,受渗漏补给潜力和包气带调蓄能力等的限制,并不是所有河流或河段都适宜开展地下水人工补给工作。目前缺乏为大家广泛接受的适宜性评估方法。本研究以永定河生态补水为契机,以北京平原段河道和下伏含水层为研究区开展了案例研究,并用实测数据对研究结果进行了检验。应用指标体系法建立的适宜性评估模型(LMBGITSC模型)包括河床土地利用类型、河床介质类型、河床宽度、河床地形坡度、包气带介质类型、包气带厚度、包气带给水度、包气带水平渗透性等8个指标。案例研究结果表明,沿河流流向,通过河道渗漏补给地下水的适宜性由好变差(防渗河段除外)。该规律主要受渗漏补给潜力和包气带调蓄能力控制,因此适宜性也呈现出“阶梯式”演变规律。检验结果表明所建的评估方法适用性较好。该方法具有可移植性,因此也可为其他同类地区提供参考。

Due to the effect of climate changes and human activities,groundwater over-exploitation and aquifer depletion have become global issues of concern.Artificial recharge of groundwater through a river has been paid more attention among a variety of artificial intervention measures.It is found that not all rivers or river reaches are suitable for artificial recharge of groundwater owing to the limitations of recharge potential by infiltration and storage capacity of the vadose zone.At present,there is still a lack of widely accepted suitability assessment methods.In this study,the Yongding River in the Beijing Plain section and the underlying aquifer are taken as the study area and the case study is carried out.Moreover,the measured data are used to verify the results.The suitability assessment model(LMBGITSC model)constructed by the index system method includes eight indexes:land use types of riverbed,sediment types of riverbed,channel width,channel topographic slope,medium types of the vadose zone,thickness of the vadose zone,specific yield of the vadose zone and horizontal permeability of the vadose zone.The results show that the suitability of groundwater recharge in the Yongding River changes from good degree to medium degree along the river flow direction(except the reaches carried out anti-seepage engineering),presenting a"step-type"evolution law.The proposed method is of good applicability and can also provide reference for similar regions.