{ Lake 21·50 to 22·50 { Ordinary flood maximum { Abûsir-el-Malaq 25·30 to 27·40 levels at end of { September. { Magnûnah mouth 26·00 to 28·00 { { Outlet, Kosheshah 24·80 to 27·00 The year 1888 was one of very low Nile flood, but even in that year, from about 20th July to 15th November, the Nile level at Magnûnah mouth was above R.L. 23·00, and reached R.L. 26·00 at the top of the flood. The quantity of water required to fill the lake from R.L. 19·50 to 22·50, and to allow for its evaporation for six months, is calculated as follows:— Million cubic metres. Volume required to raise lake 3 metres = 1600 million square metres × 3 4800 Volume required to make good 6 months’ evaporation = 1600 million square metres × 1·30 2080 Volume required for irrigation of 25,000 feddans reclaimed, for 6 months 100 ---- Total volume required 7580 The greater part of this would be poured in during the three months of flood, say 5000 million cubic metres in 100 days, or an average of 50 million cubic metres a day. There now remains to be calculated the discharge that this reservoir would give back to the Nile during the low water months. Million cubic metres. The content of the stratum of water between R.L. 22·50 and 19·50 is 1600 million square metres × 3 4800 Of this there would be lost by evaporation during the 6 months 1600 million square metres × 1 1600 ---- There would thus remain available for purposes of irrigation 3200 The reclaimed land round Arsinoë (about 25,000 feddans) would require about 50 million cubic metres for its irrigation during the 6 months of winter and summer 50 ---- The balance available for the Nile Valley would be 3150