Environmental Flow analysis

Dear Members,

I am currently working on a research to find Environmental flow in a river which has 2 main reservoirs built on it's way. There is only one gauge to measure the flow of river (This gauge is in one of the river branches which measures only branch flow) and it has only records after the dams were built. My questions are ;

1. Any method to find EF with this situation of regulated (disturbed) flow data??

2. How can I use this gauge information to find EF?

PS: I have several rainfall data around the watershed

Thank you!

Please help!!!

No any idea, but will soon give you the information. Thanlk you