Ecological Flow Spectrum and Its Change in the Headwater s of Chaobaihe River
潮白河源区生态流量的谱系及其变化

To protect and rehabilitate health of riverine ecosystem in Chaobaihe River,this paper investigated the ecological implication of the streamflow regime and proposed the concept of ecological flow.The spectrum of the ecological flow includes extreme low flow,low flow,high pulse,high flow and extreme high flow in consistent with those proposed by IHA(Indicators of Hydrologic Alteration).For the case study in the headwaters of Chaobaihe River using daily streamflow data from 1956 to 2003 of Dage Hydrological Station,because of the significant changes of hydrologic cycle,the period from 1956 to 1974 was named reference period,while 1975 to 2003 was named as influenced period.The results showed that the ecological flow spectrum of the influenced period was quite different from that of reference period.The average value of extreme low flow,low flow,high pulse,high flow and extreme high flow are respectively 1.09,2.43,6.5,14.95 and 25 m3/s in reference stage,while the influenced period extreme low flow,low flow and high flow drop respectively by 31%,4% and 9%,and the extreme high flow disappears but the high pulse was increased by 5%.From the point of view of ecological flow,if the ecological situation in reference period is acceptable for ecological restoration,it is important to increase the quantity of extreme low flow in the headwaters of Chaobaihe River.