FEEDER
CANALS were dug from the river through the basins, often connecting them in
series. The levels of the canal beds were dug halfway between the low water
mark and the ground levels of the basins. by Peter A. Piccione
Most of the land in Egypt--from ancient times to relatively recently--was irrigated by means of BASIN IRRIGATION. The fundamental principle of basin irrigation is high water canalization.
In the flood cycle, the level of the Nile began to rise in late June. Through late July and early August, the river rose rapidly. It ideally reached its high water mark in September. Thereafter, the water level began to drop before late October. It fell rapidly from November through early December, after which the entire process started again.
In its simplest form, basin irrigation utilized old and abandoned natural river levees that ran parallel to the river along the valley floor (in a general north-south direction). These levees were supplemented by earthen embankments called LONGITUDINAL or LONG DIKES. These dikes and levees were intersected and ran west to east from the desert edge to the river levee.
FEEDER
CANALS were dug from the river through the basins, often connecting them in
series. The levels of the canal beds were dug halfway between the low water
mark and the ground levels of the basins.
The entrances
to the FEEDER CANALS at the riverbank were blocked up through the early
stages of the inundation. The feeder canals were cut open at the riverbank,
allowing the inundation to fill the canals and start flooding the basins. Ideally,
the basins would fill for a 40-day period. After the 40-days of filling, the
feeder canals were closed again and blocked up. During this phase, the ground
was saturated, and a thick layer of silt settled out of the water and on to
the basin floors.
Two
weeks later--sometime in October--and coinciding with the ebbing of the flood,
DISCHARGE CANALS were
cut open, permitting the water to drain out of the basins and back into the
Nile.
21. , compare
and contrast flooding on the Nile, with flooding in the United States,
along the Missouri River.
(click on the links to get more ideas)