At the beginning of historical times in Egypt there existed many lakes and
swamps in the region, and the Nile delta was covered by a number of Nile
branches which were constantly changing their courses. Just like the alluvial
plain of the Nile valley, the Nile delta was amphibious in character. Today
there are seven Nile branches and two major canals in the extremely flat plain
of the Nile delta. The gradient towards the Mediterranean is very small at
about only 0.01 per cent, and the difference in altitude over the distance of
160 km between Cairo and the Mediterranean coast is only 20 m. There are
no natural elevations in the Nile delta. The few minor places that may seem
to be such are the remains of former settlements covered by mud or sand.
Several settlements here were destroyed by earthquakes in historical times,
like the old part of the town of Damanhour.