[raincom]

There are fundamental problems with international laws; whoever has the power, enforces its version of law. In fact, the state is founded in Law, whose enforcement depends on the monopoly on violence. That's why the State has monopoly on violence; and it takes different forms, through prosecutions, through imprisonments, etc.

Instead of talking about legal perspectives or of interests of Ethiopia or of Egypt, one can talk in terms of 'reasonableness'.

It is reasonable to use the water that drains off Ethiopian watershed; here, Egypt can't use some colonial era treaties unless it wants to colonize Ethiopia. No reasonable person will accept the claim that 95% of Nile water should go to Sudan and Egypt.

You also raise another reasonable point: "It is how long does it take for fill the dam and make it longer so that it reduce its negative effect". This is something many people agree with. However, this can't be solved using the historical outflows to the Nile. Just because 95 percent of the water went downstream to Sudan and Egypt for the last 900 years, one can't expect Ethiopia to release 95% of the water this year. This is where the real dispute lies, and that dispute manifests in terms of "how slow one has to fill up the dam". Maybe, both Egypt and Ethiopia can put percentages: Egypt can say "just release 80% this year, decrease 5% every year until it reaches 50%", or Ethiopia can say "we will release 10% every year until the dam is full". That way, one can see where both parties stand.

Law without violence(enforcement) is useless. Colonial powers had that power when they assigned most of the water to Egypt and Sudan. One can't expect this now.