Calculation Of River Ecological Flow In Cold Northern Region Based On Habitat Simulation Method ——A Case Study Of The Middle And Lower Reaches Of Mayi River

With the rapid development of economic society,production water and domestic water demand is increasing,which makes us in the pursuit of the development of the society at the same time will be different degree of damage of aquatic ecosystem.Through literature research,this study summarized and analyzed the research results of ecological water demand at home and abroad in recent ten years,and put forward the deficiency and development trend of current research on ecological water demand at home and abroad.Of this study are introduced in detail based on the principle of river flow increase method(IFIM)habitat simulation method of the theoretical basis,and this method was applied to the north cold representative rivers-the ant in the middle and lower reaches of the river section,for the first time in the study of dominant species combined with a protected species,respectively to investigate different stage fish lay eggs,fish,wintering habitat suitability;On the basis of determining the habitat suitability curve of the target species,the recommended value of ecological flow was calculated by using 2d hydrodynamic simulation in River2 D model and habitat simulation in PHABSIM model.Finally,the satisfaction degree of ecological flow in the middle and lower reaches of Mayi River in 2018 was analyzed,and feasible control suggestions were put forward based on the current situation of Ant River basin.The main conclusions of this study are as follows:(1)Through the investigation and analysis of the current situation of fish in the ant river,silver crucian carp and carp were selected as dominant species,and fine scale fish were selected as protected species.The habitat survey was carried out on the selected target fish species,and the habitat suitability curves of the water depth and flow rate of the target fish species at the spawning,adult and wintering stages were determined.(2)When targeting fingerlings with silver carp: the minimum ecological flow during the spawning period,adult stage and wintering period is 20m3/s,20m3/s,10m3/s,the most suitable ecological flow is 75m3/s,150m3/s,30m3/s;when carp is the target fish species: spawning stage,adult stage and wintering period,the minimum ecological flow is 30m3/s,10m3/s,10m3/s,the most suitable ecological flow is 50m3/s,200m3/s,40m3/s When targeting fingerlings,the minimum ecological flow of fine-scaled fish is30 m3/s,100 m3/s,20 m3/s,and the most suitable ecological flow is 75 m3/s,150 m3/s,30 m3/s.(3)The ecological flow results of the habitat simulation method and the calculation results of the hydrology method can be compared and analyzed,and the calculation results of the habitat simulation method are significantly higher than the calculation results of the hydrological method,because the habitat simulation method fully considers the needs of biological factors,so the amount of water required is obviously larger,and the results are more scientific.The calculation results are within the scope of the Tennant method,the calculation results are more reasonable,and the minimum ecological flow and the most suitable ecological flow in different periods can ensure that the fish have good spawning conditions and living conditions in the ant river.(4)In 2018,the number of days to meet the minimum ecological flow in the middle and lower reaches of the Ant River was 159 days,and the ecological flow guarantee rate was 56.44%.Among them,the months that do not meet the minimum ecological flow standard are mainly concentrated in the freezing period and the spawning period in May,and it is recommended that the ant river basin optimize the allocation of water intake and water intake time in irrigation areas,and develop the economy on the basis of meeting the ecological flow.