Low-　and　high-speed　streaks　(ejection,　Q2,　and　sweep,　Q4,　events　in　quadrant　analysis)　are　significant　features　of　coherent　structures　in　turbulent　flow.　Streak　formation　is　closely　related　to　turbulent　structures　in　several　vortex　models,　such　as　attached　eddy　models,　streamwise　vortex　analysis　models,　and　hairpin　vortex　models,　which　are　all　standard　models.　Vortex　models　are　complex,　whereby　the　relationships　among　the　different　vortex　models　are　unclear;　thus,　further　studies　are　still　needed　to　complete　our　understanding　of　vortices.　In　this　study,　30　sets　of　direct　numerical　simulation　(DNS)　data　were　obtained　to　analyze　the　mechanics　of　the　formation　of　coherent　structures.　Image　processing　techniques　and　statistical　analysis　were　used　to　identify　and　quantify　streak　characteristics.　We　used　a　method　of　vortex　recognition　to　extract　spanwise　vortices　in　the　x-z　plane.　Analysis　of　the　interactions　among　coherent　structures　showed　that　the　three　standard　vortex　models　all　gave　reasonably　close　results.　The　attached　eddy　vortex　model　provides　a　good　explanation　of　the　linear　dimensions　of　streaky　structures　with　respect　to　the　water　depth　and　Q2　and　Q4　events,　whereby　it　can　be　augmented　to　form　the　quasi-streamwise　vortex　model.　The　legs　of　a　hairpin　vortex　envelop　low-speed　streaky　structures　and　so　move　in　the　streamwise　direction;　lower-velocity　vortex　legs　also　gradually　accumulate　into　a　streamwise　vortex.　Statistical　analysis　allowed　us　to　combine　our　present　results　with　some　previous　research　results　to　propose　a　mechanism　for　the　formation　of　streaky　structures.　This　study　provides　a　deeper　understanding　of　the　interrelationships　among　different　vortex　models.