Measuring the Floods

What is Nilometer?

Nilo = the River Nile Meter = a measurement of
There are other possible words one could use for this device:
* hygrometer, pluvometer, udometer, rain gauge, fluviograph, hydrometrograph
But for purposes of this simple blog, we will use the English word referring to the ancient Egyptian structure: Nilometer.
It was an ancient device (from about 5000 years ago) and was used to measure the levels of the annual flooding of the Nile River in Egypt. Some of the nilometers were built by the Romans. The flood levels varied and were unpredictable: you only knew what was coming once the waters arrived in your land. How then, was one to measure it?

Why did they need to measure the water levels?
The level of water at the time of the floods could be used to predict the harvests for that year and thus the level of sustenance for the people of the land. These predicted harvests would then be directly proportional to how much tax the farmers would have to pay. So the higher the water levels, the better the harvests, and therefore the higher the taxes that could be demanded for that coming year. This was obviously a rather important device to the Pharaonic rulers.

What did they look like?

It is said that there were 3 types of Nilometers, and there is one of each still standing in Egypt today:
1. A vertical column
This was considered to be the simplest form. It was a large graduated column (often marble), submerged in a stilling well, situated right next to the Nile and housed in elaborate structures. There is still one to be found on the island of Rhoda in Cairo. This was built in AD 861, and is now housed in a modern conical structure. There are 3 tunnels to allow the water from the Nile into the well. There are also ornate carvings on the side of the nilometer.

2. A stairway of steps leading down, directly into the Nile
An example of this stairway Nilometer is found in Aswan. There are depth markings for measurements all the way down the stairs and on the walls. These measurements enable one to tell fairly easily the level of the river: literally the last step you can walk down without getting your feet wet is the height of the river!!
This Nilometer was considered to be the most important, as in former times, Aswan was the southern most border of Egypt, and thus the first place though which the Nile entered Egypt. So the annual floods would reach Aswan first, and this reading would then be the first prediction of the harvests and the taxes for the coming year.

3. A channel from the Nile to a deep well, usually in a temple.
This type was the most elaborate. The channel could be quite short or fairly long, and ended inside the temple in a deep cistern, with indicators carved into the wall. Traditionally it was only the rulers and priests who were allowed to read the Nilometers, so there was quite a mystical wisdom associated with this reading. The rulers and priests could predict (with alarming regularity) exactly how large the harvests would be, and therefore how much tax should be paid way in advance of the seeds even being planted. This impressed the ordinary folk, who at that time, did not know about this secret measuring tool inside the temple! An example of this can be found in the Kom Ombo temple (north of Aswan).

How did they work?

All 3 types of nilometers measure the water levels. Types 2 and 3 could also measure the clarity of the water. They could visually determine how much silt the water was carrying.

The Numbers
The measurements were in Egyptian Cubits (about the size of an average adult male forearm) and the numbers could mean literal life or death for the coming year:

18 = disaster (too high, destruction and loss of crops, homes and lives)

16 = abundance (high, but ideal: best soil and good fields)
15 = security (good levels, will bring enough food)
14 = happiness (still enough to eat, average levels)

13 = suffering (barely enough food)
12 = hunger (water level too low, not enough food produced, resulting in famine)

Are they still in use today?
With the building of the 2 dams in Aswan:
• Aswan dam (low dam) in 1902
• The High dam (1960 -1970)
they have rendered the Nilometers obsolete. The flooding of the Nile is now controlled by the dams. These dams store water, control irrigation and are used for hydroelectricity.

Although there is no longer any flooding, visitors can see each of these examples of Nilometers in Egypt today. We can remember the priests and rulers from ancient times who used to walk down the stairs and make the annual measurements, predicting harvests, destruction and taxes for the following year.