Abstract:

This research investigated the actuality and regularity of fish passing in ship lock. In addition, the field water quality and hydrodynamic force were monitored by following fleet time when fish passing through ship lock at daytime (the period of 9〖DK〗∶00 to 12〖DK〗∶00) in Gezhouba No.1 ship lock and No2 ship lock from 29th to 30th August. Hydroacoustic was applied to monitor fish passing in place of ship lock and upper lock head section. The investigation was carried out at downstream lock head section by hydroacoustic in all 24 hours (the period of 9〖DK〗∶00 to 9〖DK〗∶00 the next day) during 21th to 27th April, 18th to 22th June, 23th to 28th August, 2013. It is resulted that the ship locks have the ability of fish passing in natural condition, and they may become a new kind of fish passing building which not only has the navigation capacity but also the fish passing capacity by some improvement measures. The fish passing in ship lock performs circadian rhythm, fishes were more active at night compared with daytime, and expressed the tendency that to choose a relative suitable temperature for movement in different seasons, and it has no significant difference in the amount of fish passing in natural condition between the downstream lock head of two ship locks. Due to the suitable condition of water temperature and at the end of the forbidden fishing period of downstream of Gezhouba in June, fishes has mass rearing and the ship locks have the biggest amount of fish passing. In April and August, the water temperature was too low or too high so that it was not good for the rearing of the four major Chinese carps, leading to the comparatively small amount of fish passing, and it has no significant difference on the mean value after being compared. What's more, the change of water level and velocity in different month may have some effects on the amount of fish passing. The downstream fish density in two ship locks satisfied the need of fish passing ability in natural condition, and the difference of downstream fish density in two ship locks is not the key factor which limits the present fish passing ability of two ship locks. The fish can be induced to get in the ship locks from the downstream approach channel by taking fish some luring measures. As a result, the amount of fish passing in ship locks can be improved. A part of fishes keep staying in the ship locks after swimming inside the ship locks, because they did not get out of the ship locks when the water level rose. But they would swim downstream out of the ship locks back to downstream while the downstream ship lock gate opened again. It is explained that the upper lock head is the another key node of fish passing in ship locks, the upper threshold is the natural barrier for fish passing in ship locks. The fishing passing rate at upper lock head section were respective 21% and 42% in Gezhouba No.1 ship lock and No.2 ship lock.