Study On The Ecological Flow Of Coreius Spawning During The Integrated Water Temperature And High Flow Pulse Process

Ecological flow research is an important basis for reservoir ecological regulation,river ecological protection and natural hydrological situation restoration practice.The impact of hydropower development on the ecological environment of rivers is mainly divided into two categories:habitat and organisms.The study of changes in habitat factors such as river hydrology,water environment,and sediment caused by damming to spawning and habitation of fish and other organisms in the river Due to the influence of local environment,scientifically carrying out reservoir ecological dispatch is the hot spot of current ecological flow research.Along with Xiangjiaba and Xiluodu water storage operations,the amount of early fish resources in the National Nature Reserve for Rare and Endemic Fish in the upper reaches of the Yangtze River(hereinafter referred to as “protection zone”)has been in a downward trend since the long-term monitoring was carried out in 2007.In this paper,copper fish with a larger proportion in the protected area and more monitoring data are selected as representative fish.The comprehensive water temperature process and high flow pulse process have systematically explored the ecological flow requirements of copper fish spawning and breeding.It is of great significance to the protection of fish in the reserve,and also plays an important role in guiding the ecological regulation of dam-building rivers.Based on the 2009-2016 Coreius spawning data from the Jiangjin section of the protected area and the flow data and water temperature data of Zhutuo station,the paper statistically analyzed the spawning characteristics of Coreius,and compared the water temperature characteristics and high flow pulses before and after the storage operation.The change of the characteristics provides an effective accumulated temperature index for the water temperature process,and the seven characteristics of the high flow pulse occurrence number,duration,starting flow,initial increase,peak flow,peak flow corresponding to the duration and average increase for the high flow pulse process Indicators,to count the characteristics of each indicator and analyze the correlation between each indicator and the spawning scale of Coreius.The integrated water temperature and high-flow pulse process put forward ecological flow requirements that are beneficial to the spawning and reproduction of Coreius.The results of the study show that statistical analysis of the characteristic indexes of the water temperature process and the high-flow pulse process of the egg production of the Coreius before and after the storage operation is carried out.According to relevant analysis,it was found that the water temperature range for the first spawning of the Coreius is 20.8-23.3?,the optimum water temperature on the spawning day is 21.4-21.9?the biological zero of the effective accumulated temperature of the egg production of the Coreius is 13?,and the average effective accumulated temperature of the Coreius breeding year is 1508.4±71.0?·d,The spawning is mainly affected by the effective accumulated temperature of 13-17?from March to April before the spawning period of this year;after meeting the effective accumulated temperature of 13-17?,three high-flow pulses should occur every year.The first high-flow pulse occurred from May12 to May 24,lasting 3-7 days,with a rising flow of 4010-4550m~3/s,an initial increase of 740-1000 m~3/s,and a peak flow of 4890-6417 m~3/s,the peak flow corresponds to the duration of 2-5d,with an average increase of 170-471 m~3/s;the second high-flow pulse occurs from June 3 to June 15 and lasts for 3-10d.4700-6206m~3/s,initial increase 760-1642 m~3/s,peak flow 6920-11073 m~3/s,peak flow corresponding to 1-8d,average increase 317-986 m~3/s,the third high flow pulse The time of occurrence is June 21st to July 5th,which lasted 4-7days.The high-flow pulse starts from 6185-8091m~3/s,the initial increase is 1340-1690 m~3/s,the peak flow is 9230-12992m~3/s,peak The flow rate corresponds to1-5days,with an average increase of 425-1460 m~3/s.