考虑河床渗透性影响的基流退水过程解析模型  

An analytical model for baseflow recession considering riverbank permeability

作　　者：王国梁 梁修雨 Wang Guoliang;Liang Xiuyu(School of Environment,Southern University of Science and Technology,Shenzhen Guangdong 518000,China)

机构地区：[1]南方科技大学环境科学与工程学院,广东深圳518000

出　　处：《地质科技通报》2023年第4期201-209,共9页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金项目(41977165);深圳市高等院校稳定支撑计划项目(20220814221815001)。

摘　　要：基流退水过程分析是流域尺度平均水文地质参数估计的有效方法之一,但传统基流退水过程模型未考虑河床的渗透性,其对参数估计的影响并不清楚。针对这个问题,建立了降水入渗及河水位波动驱动下,考虑河床渗透性影响的潜水含水层地下水流数学模型,运用格林函数方法推导出水位及流量的解析解,并利用数值模拟验证了解析解。结果表明,在降水入渗强度波动的驱动下,河床渗透性越小,降水入渗引起更高的地下水位上升,更低的基流量峰值,更慢的基流退水过程;河水位波动驱动下,河床渗透性更低时,地下水位对河水位波动的响应更弱,地表水-地下水交互通量更小;河床渗透性显著影响基流退水曲线,退水早期,低渗透性的河床导致曲线斜率远大于3,而退水后期,曲线斜率趋近于1,且其不受河床渗透性影响。当河床渗透性较差时,由于忽略了河床渗透性的影响,传统模型会过高估计基流量,过低估计含水层的渗透系数。[Objective]Baseflow recession analysis is an effective approach to estimating watershed-scale hydrogeological parameters.However,the traditional baseflow recession model did not consider the effects of semipervious riverbanks,and their influence on parameter estimation is unclear.[Methods]To address this issue,a mathematical model for groundwater flow in an unconfined aquifer with time-dependent recharge and river stages is presented.The effects of the semipervious riverbank are specifically taken into consideration.The analytical solutions of the hydraulic head and discharge are derived by using Green's function method,and their validities are tested by numerical simulations.[Results]The results show that,forced by the fluctuating recharge rate,the lower riverbank permeability leads to a higher peak of hydraulic heads,a lower baseflow,and slower baseflow recessions.For the case forced by the fluctuating river stages,the lower riverbank permeability leads to the weaker responses of water flow to the fluctuated river stage and the lower fluxes of surface water-groundwater interaction.The riverbank permeability significantly affects the baseflow recession curves.During early stage,the low riverbank permeability caused the power index of the recession curve to be larger than 3.For later stage,the power index approaches 1,which is not affected by the riverbank permeability.[Conclusion]For a low riverbank permeability,the traditional model will overestimate the baseflow and underestimate the hydraulic conductivities of aquifers because it neglects the effects of riverbank permeability.

关 键 词：基流退水过程 含水层补给 河水位波动 河床渗透性 解析解 

分 类 号：P641[天文地球—地质矿产勘探]