Why was Egypt interested in controlling the sources of nile​

The Nile River occupies a central place in the general perception of all Egyptians since the pre-Christian era of ancient Egypt. The river has been the nucleus of the ancient world and its lifeline, thereby justifying the sanctification of its waters. Ancient Egypt could not have existed without the river Nile. Since rainfall is almost non-existent in Egypt, the floods provided the only source of moisture to sustain crops.

Gun but i don’t know for sure