关键词: 河流-含水层相互作用, 水力耦合模型, 三角网格差分法

Abstract: Based on theanalysisofhydraulicm echanism ofstream - aquiferinteraction sys- tem, an integrated m odelis developed to sim ulate the interaction process. To allow accu- rate sim ulation ofthesystem response, stream flow and ground waterflow aresim ultane- ously m odeled and a water exchange m echanism which can dealwith continuous flow and noncontinuous flow is designed to integrate the stream flow m odeland ground waterflow m odel. Mathem atically, the stream flow issim ulated by using Saint- Venant’s continuouse-quation w ith stream storage neglected and Euler’sApproach isem ployed to generate solu- tions to the equations. The stream system is discretized by im posing a grid ofretangular cells that are assigned num ericalvalues for selected hydrologic conditions and hydraulic properties. Ground w aterflow m odel, w hich isin the form ofphreaticaquiferequation, is solved with finite difference m ethod ofirregular triangulated netw orks. To integrate the m odels, the stream nodes overlap the aquifernodes where stream spass. The volum e of w ater exchange betw een stream s and aquifers is sim ulated by using Darcy’slaw, w hich isbased on thedifference betw een stream stage and watertable in the cell, and theverticalhydraulicconductivity ofthestream bottom, and itreachesthem axi- m um degree when noncontinuous flow occurs beneath the stream bottom . It can be ex- pressed as: (E= m in[γ·(H_{r - (H) ·η,Em,qu] (H < (Hr γ·((Hr - (H) (H ≥(Hr (1-3) where E(m /d) is the exchangerate, γ= kzm, k(m /d) and m (m ) are theverticalhydraulic conductivity and thethicknessofthepoorly perm eablestrataon the stream bed respective- ly, (Hr(m ) is the stream stage, (H(m ) is the ground w atertable, Em (m /d) is the m axi- m um perm eability capacity ofthepoorly perm eablestrata and qu= Q/·1/W, Q,Land W are the stream flow, stream coordination and stream w idth respectively, and ηisa dim ension- less factorwhich isinversely proportionalto sand contentofthe stream w ater. Acasestudy showsthatthe integrated m odelcan accurately sim ulatestream flow and ground w ater m ovem ent and the calculated volum e of each stream section flow m atches properly w ith theobserved values. Thefactsprovethatthem odelresultsareaccurateand reliable.}

Key words: stream -aquiferinteraction, integrated m odel, finitedifferencem ethod ofirreg- ulartriangulated netw orks