In the matter of floods the Tigris and Euphrates present a striking contrast to the Nile.  It is true that the life-blood of each country is its river-water, but the conditions of its use are very different, and in Mesopotamia it becomes a curse when out of control.  In both countries the river-water must be used for maturing the crops.  But while the rains of Abyssinia cause the Nile to rise between August and October, thus securing both summer and winter crops, the melting snows of Armenia and the Taurus flood the Mesopotamian rivers between March and May.  In Egypt the Nile flood is gentle; it is never abrupt, and the river gives ample warning of its rise and fall.  It contains just enough sediment to enrich the land without choking the canals; and the water, after filling its historic basins, may when necessary be discharged into the falling river in November.  Thus Egypt receives a full and regular supply of water, and there is no difficulty in disposing of any surplus.  The growth in such a country of a legend of world-wide destruction by flood is inconceivable.

In Mesopotamia, on the other hand, the floods, which come too late for the winter crops, are followed by the rainless summer months; and not only must the flood-water be controlled, but some portion of it must be detained artificially, if it is to be of use during the burning months of July, August, and September, when the rivers are at their lowest.  Moreover, heavy rain in April and a warm south wind melting the snow in the hills may bring down such floods that the channels cannot contain them; the dams are then breached and the country is laid waste.  Here there is first too much water and then too little.

The great danger from flood in Babylonia, both in its range of action and in its destructive effect, is due to the strangely flat character of the Tigris and Euphrates delta.(1) Hence after a severe breach in the Tigris or Euphrates, the river after inundating the country may make itself a new channel miles away from the old one.  To mitigate the danger, the floods may be dealt with in two ways—­by a multiplication of canals to spread the water, and by providing escapes for it into depressions in the surrounding desert, which in their turn become centres of fertility.  Both methods were employed in antiquity; and it may be added that in any scheme for the future prosperity of the country they must be employed again, of course with the increased efficiency of modern apparatus.(2) But while the Babylonians succeeded in controlling the Euphrates, the Tigris was never really tamed,(3) and whenever it burst its right bank the southern plains were devastated.  We could not have more suitable soil for the growth of a Deluge story.

     (1) Baghdad, though 300 miles by crow-fly from the sea and
     500 by river, is only 120 ft. above sea-level.