Vegetation　patches　constitute　the　foundational　elements　of　river　dynamic　systems,　often　forming　communities　within　channels.　This　study　examines　how　the　interaction　between　neighboring　vegetation　patches　influences　flow　structure.　A　pair　of　adjacent　vegetation　patches,　constructed　from　staggered　rigid　cylinders　with　varying　densities,　is　used　in　the　experiments.　The　findings　indicate　significant　differences　in　flow　structure　when　water　traverses　these　adjacent　patches　compared　to　an　isolated　patch.　Hence,　a　flow　structure　partition　for　adjacent　patches　is　proposed,　including　an　upstream　adjustment　region,　a　vegetation　interior　region,　a　shear　layers　region,　and　a　wake　merger　region.　The　upstream　adjustment　length　indicates　the　distance　upstream　from　the　obstruction　where　velocity　starts　to　deviate　from　its　far　upstream　value.　This　reduction　in　velocity　is　pronounced　in　denser　patches,　although　the　upstream　adjustment　length　remains　unaffected　by　vegetation　density.　The　velocity　at　the　centerline　of　each　patch　significantly　decreases,　whereas　the　velocity　between　the　patches　increases　rapidly,　a　characteristic　of　the　vegetation　interior　region.　The　reduction　in　individual　patch　velocity　is　again　observed　in　denser　patches.　In　the　downstream　area,　the　shear　layers　region　extends　from　the　trailing　edge　of　the　patches　to　the　point　of　minimal　velocity　behind　each　isolated　patch.　With　increasing　vegetation　density,　the　smallest　velocity　approaches　zero,　while　the　length　of　the　shear　layers　region,　denoted　as　L1,　initially　decreases　before　stabilizing.　The　highest　velocity　on　the　centerline　between　the　patches　occurs　near　the　trailing　edge,　with　the　lowest　velocity　observed　at　a　distance　(x/D=Lm)　from　the　trailing　edge.　As　vegetation　density　increases,　the　maximum　velocity　on　the　centerline　between　the　patches　rises,　but　the　minimum　velocity　and　Lm　decrease.　The　difference　(Lm–L1)　defines　the　length　of　the　wake　merger　region;　here,　the　centerline　velocity　of　each　patch　increases　and　aligns　with　the　velocity　on　the　centerline　between　the　patches,　causing　the　wakes　directly　behind　each　patch　to　merge　into　a　single,　larger　entity.　In　addition,　the　formulas　for　the　exit　velocity,　steady　wake　velocity,　and　minimum　centerline　velocity　of　the　two　patches　are　presented.　©　2024　Sichuan　University.　All　rights　reserved.