Abstract: To explore the fish adaptability under various hydraulic factors during the process of fish tracing in a vertical slot fishway, it is necessary to simulate the fish migratory trajectory. In this study, a numerical model was used to calculate the flow field and the field of turbulentkinetic energy and its dissipation rate in a vertical slot fishway. An influence coefficient for each hydraulic factor was endowed by the degree of fish preference on them. With this method, themigratory trajectory of a fish was modeled and adjusted by results from previous laboratory experiment. The results showed that the field structure of turbulent kinetic energy influenced the fish trajectory most profoundly since most the tracing points appeared nearby a threshold value ofturbulent kinetic energy. The influence of centripetal velocity was limited but not negligible, because it is a key factor in the process of continuous fish traceability. The influence of the turbulence dissipation rate could be negligible.

Key words: microbial organic carbon, soil aggregates, dissolved organic nitrogen, microbial organic nitrogen, particulate organic nitrogen., nitrogen deposition, dissolved organic carbon, particulate organic carbon