Study On Effect Of Dam Operation On The Natural Reproduction And Repair Measures Of The Acipenser Sinensis

Acipenser sinensis is not only the ancient but also an endemic and rare species.However, with the construction of the GeZhouBa project in1981, the migration channel ofit has been blocked, moreover, the main spawning ground has been decreased to about4.5km below the GeZhouBa dam from the original800km in the Yangtze River. Althoughthe construction of the Three Gorges Dam has no influence on the migration of theAcipenser sinensis, relative to the GeZhouBa, the Three Gorges Reservoir has a largerregulation performance, which would change the hydrological and hydrodynamicenvironment in the downstream. Along the development of the large cascade hydropowerstation at the upstream(such as the cascade reservoirs of jinshariver and yalongriver), ansuperimposed effect about hydrology would came into being, the hydrological andhydrodynamic environment at the downstream of the GeZhouBa would changefundamentally. The research on the living environment of the Acipenser sinensis,especially on the hydrodynamic environment which is influenced by the operation of thedam not only can supply the monitoring data of the hydrological and hydrodynamicenvironment during the propagation of the Acipenser sinensis, but also has an importantguiding significant on the repairing and rebuilt of the natural spawning of the Acipensersinensis. Besides, it can provide some references to the ecological reservoir reoperation. Inthis paper, the measure which combined the theoretical analysis, mathematical statisticsand numerical analysis has been taken to study the repairing and rebuilt measures of thespawning and habitat of the Acipenser sinensis which is under the influence of theoperation of the dam. And the main research results are as follows:(1)Through the study on the life habit of the sturgeons, the influence on the fishhabitat that caused by the construction of the dam and the data collection about the modelof the fish habitat to obtain the life trait of the Acipenser sinensiss and the protection statusof the bahitat.(2)Based on the monitoring data that has been collected, summarized the change ofthe spawning environment for years, then factor analysis the impact factors(velocity, waterdepth, water temperature, sediment, sediment concentration and so on). As a result, threemain factors has been found out, velocity, sediment concentration, and sediment affectedthe egg incubation conditions of the Acipenser sinensis most, water temperature and thenumber of the egg-eating fish affected the survival condition of the Acipenser sinensis eggsmost. (3)The analysis about the hydrodynamic environment in the spawning ground of theAcipenser sinensis and the variety of the WUA. Combining the suitability curve of thehabitat which is been optimized and the3-D hydrodynamic model together, to simulate thespawning ground of the Acipenser sinensis and the suitability before and after the ThreeGorges Reservation of water(from the interception of the GeZhouBa). The research showsthat: under the capacity of flood storage of the Three Gorges, the dischargevolume(considered the GeZhouBa as a run-of-river hydropower station) shows an obviousquadratic function relation with the WUA, the peak occurs while the volume is15000m3/s.It can provide a reference for the ecological reservoir scheduling of the natural propagationof the Acipenser sinensis.(4)The analysis about the hydrodynamic environment in the spawning ground of theAcipenser sinensis and the variety of the WUA based on the schedule of the GeZhouBa.Combining the suitability curve of the habitat which is been optimized and the3-Dhydrodynamic model together, to simulate the spawning ground of the Acipenser sinensisand the suitability under a variety of situations of the unit opening. The research shows that,the great river unit should be opened first while the discharge volume cannot meet thedischarge volume that all of the units of the GeZhouBa is opened. Under this situation,increase the ability of the discharge of the great river would change the WUA. The value ofWUA is adding with the add of the discharge capacity, while the added value of thedischarge capacity is within0~200m3/s, and decrease while the discharge capacity is over200m3/s.(5)Put forward the improvement measures. On the one hand, ecological reservoirscheduling can be adopted during the laying season of the Acipenser sinensis, on the otherhand, the methods excavation or placement the precast construction to optimize thesediment and the terrain structure that fit for the laying of the Acipenser sinensis canimprove the hydrodynamic environment of the habitat of the Acipenser sinensis.