Ravelli: Irrigation and Drainage in Ancient Latium (1987)

This paper was published in Transactions (Vol. 2) of the Thirteenth International Congress on Irrigation and Drainage, Casablanca, Morocco, 1987, organised by the International Commission on Irrigation and Drainage (ICID).

IRRIGATION AND DRAINAGE IN THE WRITINGS OF THE EARLY ROMAN AUTHORS

Franco Ravelli * - Paula Howarth

SUMMARY

In this paper the authors present the results of a re-reading of the works of early Roman writers they had undertaken on the occasion of their study Etruscan cuniculi: tunnels for the collection of pure water presented at the Second Special Session on History of Irrigation held in Fort Collins, U.S.A., 1984.
Attention is turned to the topic of irrigation and drainage in Latium in the last millennium B.C. when the climate, which was rainier than it is today, was gradually becoming less rainy.

* * *

The ancient technique of excavating cuniculi for the purpose of collecting water is typical of countries in the Mediterranean Basin and the Middle East. It has been used in the Middle East since the beginning of the 1^st millennium B.C. In many countries cuniculi still function today and are maintained.
At the Second Special Session on the History of Irrigation held in 1984 in Fort Collins, U.S.A., the authors of this note presented the results of a study they made on the cuniculi in Latium, central Italy.
There are many functional differences between the cuniculi in Latium and those in arid countries of the Middle and Near East and North Africa.
The cuniculi in many areas of Iran, Iraq, Arabia, Morocco, etc. have been excavated at such a depth (even twenty metres) that the water table bas been intercepted. Such cuniculi, excavated in the bottom of more or less vast valleys, often form well organised systems for collecting water to irrigate oases or settlements (Fig. 1).

Fig. 1 System of cuniculi (khettara) along the Tafilalet Valley (in Morocco, east of the High Atlas mountains). The water collected is used for irrigating the oasis visible in the background of the photograph.

By comparison the cuniculi of Latium (Fig. 2) appear to have generally served small independent communities, are limited in their extension and were excavated at a relatively shallow depth (rarely more than five metres). The cuniculi in Latium were not excavated in the bottom of the valley but along the contour line of the hillsides at a slight inclination in order to permit the flow of the water which had infiltrated into the cuniculi. A slight increase in the dryness of the climate (3^rd century B.C.) was enough to put them out of order and make continued excavation pointless.

Fig. 2 Etrusco-latin cuniculus on the side of a hill near the via Torrevecchia on the outskirts of Rome (Italy). The bushes growing around the opening of the shaft are visible. The outlet of this cuniculus is on the left hand side of the photograph in correspondence with a curve in the valley.

These cuniculi had been excavated, for the purpose of collecting pure water, by the Etruscans and Latins in the "pozzolana" and "tufo" deposits left by volcanoes, now extinct, which extended north and south of Rome in a direction parallel to the sea.
Attention was given in that study to the historical and archeological framework in which the cuniculi are to be placed. A summary of the results of that study is to be found in the synoptical table (below) which shows that the place and period in which cuniculi were excavated coincide with a series of conditions. The main ones are:

PHYSICAL CONDITIONS

- "pozzolana" and "tufo" deposits whose permeability decreases from above to below;
- a climate which was rainier than today's (cuniculi are now generally dry);

SOCIAL CONDITIONS

- permanent settlements.

Synoptical table of ancient Latium.

These and other considerations on the functions and structural characteristics of cuniculi (made in the first note) led the authors to believe that cuniculi were excavated in Latium between the 8^th and 4^th century B.C. for collecting drinking water and, only secondarily, for the drainage of limited areas (a documented opinion) and for irrigation of cultivated lands (an undocumented opinion).
The study has, among other things, confuted the opinion of some scholars who interpreted cuniculi as drainage works serving hygienic sanitary purposes excavated in Roman times as a protection against malaria.
The authors, accordingly, proceeded to re-read the works of the early Roman writers paying particular attention to passages in which explicit or implicit reference is made to the topic water and agriculture.
If the cuniculi had been excavated by the Romans, one could expect to find some mention of them in the works of the early Roman writers, in particular the latin georgic ones, for whom the relationship between water and living conditions was a favourite theme both as concerns its sanitary aspects (climate, reclamation, malarious conditions, drinkableness) and agronomic techniques for protection against excesses and deficits of the hydrologic regime (drainage and irrigation).
Just what do these ancient writers say on the matter?
The first Latin author to write about agriculture was M.P. Cato (234 - 149 B.C). In his book Liber de agricultura, a collection of empirical maxims on the life and work of farmers, Cato mentions the need for drainage and describes drainage techniques: open ditches or blind ditches with stones or bundles of bush (Chap. XLIII and CLV).¹ He makes no mention of cuniculi or malarious conditions. Although he mentions symptoms of disease (Chap. CLVII), which according to some interpretations could be attributed to malaria, it seems that nothing precise can be deduced. As concerns irrigation, Cato simply mentions vegetable gardens and irrigated pastures (Chap. I and IX).
More than a century later lived M.T. Varro (116-17 B.C.), one of the most erudite men of his times. Little of his work has survived. Only three books of his De re rustica have come down to us. In this work, for the first time in Latin literature a clear indication of the danger of contracting malaria in the Rome area is given (Lib. I, Chap. IV and XII). In it Varro cites Hippocrates who several centuries earlier had dealt with the spread of malaria (see below). On the topic of irrigation and drainage Varro writes briefly of the need to drain excess water (Lib. I, Chap. VI and XXIX), although he makes no mention of cuniculi. He deals more extensively with irrigation, apparently a technique widely practiced at that time (Lib. I, Chap. VII, XXXI, XXXIII, XXXV, XXXVI, XXXVII; Lib. II, Chap. V). Irrigation does not seem to have been an important topic for these authors, although at a later date Varro does deal with the matter more frequently and in more detail than did Cato.

Fig. 4 Drainage tiles found in Alatri (65 km south-east of Rome, Italy). These tiles were laid without being sealed one to another with nortar as generally used in aqueducts (see note in the text).

Fig. 5 Tile from a Roman aqueduct found near the locality "Divino Amore" (15 km south of Rome, Italy). Note the remains of mortar used to join these tiles. No mortar was present in the drainage tiles shown in Fig. 4.

As concerns this apparent late spread of irrigation practices it would be interesting to clarify to what extent this was due to the climate which was wetter than the present day climate and to the fact that intensive agriculture was practiced later in Latium than in the Middle East where Mesopotamian civilizations had already made great achievements in hydraulic-irrigation technology.
De re rustica by L.G.M. Columella (active in Rome in 41 B.C.) is the work of a scholar of agriculture rather than that of a compiler. It presents a detailed outline of the agricultural knowledge of the time. In Lib. I, Chap. V he writes: "And neither should there be any marsh-land near the buildings, and no military highway adjoining; for the former throws off a baneful stench in hot weather and breeds insects armed with annoying stings, which attack us in dense swarms; ... from which are often contracted mysterious diseases whose causes are even beyond the understanding of physicians;" making a clear reference to the problem of malaria. Incidentally, it is strange that he should associate swamps and military roads. Columella frequently recalls the practice of irrigation and drainage by means of open and blind ditches giving precise details thereon in Lib. II, Chap. II.
The foregoing comments support the opinion that already in Cato's time cuniculi were no longer being mentioned, not only because they were no longer being excavated but also because existing cuniculi no longer functioned on account of the reduced rainfall regime. Malaria, not yet endemic in Cato's time became a source of worry for Varro; by Columella's time it had become a social scourge. This leads one to believe that there was no connection between defences against malarious swamps and the technique of drainage by cuniculi.
The Greek medical writer Hippocrates of Cos (460-377 B.C. circa) was the first to write about malaria, in particular dealing with its spread in Greece and Asia Minor (Epidemia, Lib. I and II). As pointed out by W.H.S. Jones, R. Ross and G.G. Ellett (1907), the first references to malaria in latin are to be found in a play Curculio by T.M. Plauto (245-184 B.C.) in which the servant Palinurus says (Act I, ver. 17):

...... Did a fever leave you yesterday or the day before?... ...

An even more explicit reference to malaria is made by the latin playwright P. Terence Afro (190-150 B.C.) in the conversation between Sostrata and Pamphilus in Hecyra (Act III, ver. 359):

...
So.: What kind of disease is it?
Pan.: Fever.
So.: Quotidian ?
Pan.: So they say.
...

These lines become clearer if one remembers that there are three types of malaria-bearing parasites and corresponding fevers: the quartan fever with an access every three days, the tertian fever with an access every two days, and the quotidian fever with a daily access. It should be noted that Sostrata's question "Quotidian" (Lat. Cotidiana) is erroneously translated as "continuous" thus depriving the adjective of its meaning of periodicity or intermittence, typical of malarial fevers.
After the two playwrights and Cato, Cicero (106-43 B.C.) was the next to mention malaria. A contemporary of Varro, he mentions the tertian and quartan fevers.
The first ancient Roman writer to mention malaria in medical terms was A.C. Celsus in the 4^th century B.C.
In conclusion it may be held that:

- the rainy climate of the 1^st millenniume B.C. became warmer and less rainy from the 3^rd century B.C. onwards;

- malaria began to spread in Italy from that date onwards;

- cuniculi were excavated by Etruscans and Latins in the rainier centuries or the I^st millennium B.C. (8^th - 4^th century B.C.);

- the earliest Roman writers paid more attention to drainage than did their successors who shifted their attention to irrigation. It is generally believed that irrigation, which began to be practiced from the 4^th - 3^rdcentury B.C. onwards, only became a common practice about 200 years later. Early Roman writers recorded this development with a certain delay.

The Roman historian T. Livio (59 B.C. - 17 A.D.) was the first to write about Etruscan cuniculi. He describes them solely as tunnels excavated by Roman soldiers for the purpose of secretly entering the city of Veio during the wars of expansion.
Before Livio, the Greek historian Polybius (circa 203-121 B.C.) had written about cuniculi in The Histories. Describing the places where the Syrian King Antiochus III had fought wars against Ptolomy King of Egypt and Arsace King of Parthia, Polybius referred to Iranian qanats, similar to Etruscan cuniculi, which had been excavated by the inhabitants of those regions to drain water for drinking and irrigation purposes and which still function today.

BIBLIOGRAPHY

SECCHI, A., Intorno ad alcune opere idrauliche rinvenute nella campagna di Roma, Atti Accademia Pontificia Nuovi Lincei, Roma, 1876.

JONES, W.H.S., ROSS, R., ELLETT, G.G., Malaria - A neglected factor in the history of Greece and Rome, McMillan and Bowey, London, 1907.

RAVELLI, F., HOWARTH, P.J., Etruscan cuniculi : Tunnels for the collection of pure water International Commission on Irrigation and Drainage, New Delhi, Transactions of XII International Congress on Irrigation and Drainage, Fort Collins - U.S.A., vol. II, 1984.

* ITAL-C.I.D. (Comitato Italiano per l'Irrigazione e la Bonifica Idraulica), c/o Ministero dell'Agricoltura, Via Sallustiana, 00187 Roma, Italia.

¹ As concerns tile drainage, two terracotta tiles on display at the exhibition Water and Aqueducts in Rome. 4^th century B.C. - 20^th century (Acque e acquedotti a Roma. IV sec. a.C. - XX sec.), held in the Museum of Roman Civilization in Rome at the end of 1986, were indicated as being tile drains of the Roman period (Fig. 4). These tiles appear to be the same tiles that Father A. Secchi had found in 1876 near Alatri about 65 km south of Rome (and subsequently displayed in the former Lateran Museum in Rome). In his opinion these were drainage tiles as they fitted into one another, end to end, but had not been sealed.
Although the authors agree that the tiles' function might have been drainage, their very large dimensions suggest that they did not drain cultivated fields, but rather formed an isolated line-drain that could have served to make an excessively damp area practicable or to collect water from an aquifer which probably existed at that time.