Abstract:

Large cascaded reservoirs generally hold very large regulating storage.The running of the reservoirs exerts great effects on the natural discharge process along the river course below the dam.The runoffgroup’s characteristics are changed which have important ecological meaning，such as flood，high flow pulse，low flow and extreme low flow.Pingshan section’s ecological flow group’s characteristic value under natural condition was given，based on the river’s ecological flow discharge effect theory，suggested by BRAIN，after considering the relation between the Pingshan section’s hydrology and river’s ecology of Jinsha River and choosing target year group to make calibration to the parameters of high flow pulse and extremely low flow.The daybyday flow discharge processes were modeled after the construction of cascaded reservoirs along Jinsha River course，the characteristic value of every ecological flow group was given and the modeled result was compared with that under natural condition，the effect on the Pingshan section’s ecological flow process caused by the WudongdeBaihetanXiluoduXiangjiaba cascaded reservoir constructed along Jinsha River course was analyzed.The results show that some changes of “extreme low flow never appeared，low flow increased，high flow pulse fragmented and flood kept” may take place at the Pingshan section  after the dams’ construction.

Key words: ecological flow/ large reservoirs/ Jinsha River/ Pinshan section/ natural river