River ecological flow threshold and multi-time scale guarantee rate calculation based on hydrological regime changes
An ecological flow calculation method based on quartiles of hydrological ensemble is proposed to enhance the adaptability of river ecological flow threshold and guarantee rate calculation to natural hydrological regime changes.Long series of measured runoff data of a river were classified inter-annually and intra-annually according to different hydrological scenarios,and the lower limits of ecological flow threshold for flood season and non-flood season in a year were determined based on the median and lower quartile of the ecological flow hydrological ensemble.The ecological flow calculation results in wet and normal hydrological years were taken as the ideal values of ecological flow in normal and dry hydrological years,respectively,and the guarantee degree of ecological flow in the river on different time scales was analyzed based on the ecological flow guarantee rate for the mid-long and short terms.A case study of the lower Fuhe River shows that the analytical method that integrates ecological flow thresholds and multi-scale guarantee rates,is more adaptable to inter-annual and intra-annual changes in hydrological regime in natural rivers,and it can identify the hydrological health status of rivers more accurately.The average lower limits of ecological flow threshold of the lower Fuhe River were 156.49,90.43,and 29.54m3/s in wet,normal,and dry hydrological years,respectively.The guarantee degree of ecological flow in the lower Fuhe River was low on different time scales,and the ecological flow guarantee rate of mid-long term is higher than that of short term,with values ranging from 63.64％to 93.11％and 42.50％to 91.85％,respectively.
ecological flowthresholdecological flow guarantee ratehydrological regimelower Fuhe River
万方数据
维普
