Abstract: To reveal the physical transport processes in a small urban stream and analyze exchange processes between water column and transient storage zone under base flow, field experiment using LiBr as conservative tracer and numerical simulation using One-dimensional Transport with Inflow and Storage model (OTIS) were carried out to quantitatively characterize hyporheic exchange. The longitudinal dispersion coefficient (D) reach-scale transient storage area (A_S), main channel cross section area (A), and the hyporheic exchange coefficient (α) were estimated along a 1 300 m stream reach. Transient storage metrics D_aI and E_RMS values showed an excellent fit of the model. The results of four stations (A, B, C and D) downstream the location of tracer injection demonstrated that hydrological parameters D, A_S, A, α varied with hydrological conditions. The hyporheic exchange of upper reaches (0—600 m) was weak and convection and dispersion were dominant processes. The middle reaches of the river (600—1 300 m) had stronger transient storage and longer hydraulic retention time. The exchange coefficient of segment BC (600—1 000 m) and CD (1 000—1 300 m) were (3.42×10^-6±0.65×10^-6) s^-1 and (2.87×10^-6±0.81×10^-6) s^-1, respectively. A lateral flow of 2.2×10^-5 m³/(s·m) contributed to BC. In general, stream channelization and lack of sediment on the streambed reduced the capacity of hyporheic exchange in urban streams.