U Puppini's plenary: ICM 1928

The International Congresses of Mathematics took place in Bologna, Italy, in from 3 to 10 September 1928. Umberto Puppini, Director of the Royal School of Engineering of Bologna, was an organiser and a plenary speaker at the Congress. Puppini was a member of the Ordinary Committee and a member of the Executive Commission. He also represented the National Union of Fascist Engineers.

At 15.00 on Monday 3 September, the General Assembly of the Congress met in the main hall of the Chemical Institute. Salvatore Pincherle was appointed as President of the Congress. The President gave the floor to David Hilbert for the lecture Probleme der Grundlegung der Mathematik. The lectures of Hadamard and Puppini followed at 16.00: Jacques Hadamard, Le développement et le rôle scientifique du Calcul fonctionnel, and Umberto Puppini, Le bonifiche in Italia. We give a version of an extract from Puppini's lecture.

Reclamations in Italy

1. - We give the word "reclamation" a very broad meaning. We mean all that range of works that serve to put areas of land in a state of happy culture and healthy habitability which, due to situations either natural or man-made, could not be profitably cultivated or hygienically inhabited.

Both lowland and mountain land may be in need of reclamation. The essential characteristic of an area to be reclaimed can be manifested both in the need to remove stagnant or badly draining waters, and in that of the supply of drinking and irrigated water, and in both needs together. To which necessities and related hydraulic measures are considered today all the necessary for works for the agricultural, hygienic and demographic arrangement: therefore works of agricultural land arrangement, construction of houses, building of roads, anti-malarial measures all fall within the framework of the so called complete reclamation, a framework that can therefore be said to coincide with that of the total redemption of a region.

But, in this short talk, I intend to concentrate mainly on those hydraulic reclamation works which present hygienic and economic advantages of prevailing social interest and that are related to the removal and management of water, that is, on the works that are first, the fundamental, which are indispensable for the subsequent agricultural, hygienic, road and building constructions to begin reasonably, and begin to come to fruition, and when they are completed, they will remain lasting and effective. The works, to which the very significant statistical data that I will shortly refer to, therefore mainly reflect the excavation of drainage channel networks and the construction of the related artefacts, and among these the water-pumping plants; they also include certain mountain and valley arrangements of rivers and streams; they also include cases of high interest in which the share of the land surface has undergone a general lifting by means of bridging works.

2. - I do not intend to be an enunciator and claimant of primacy. But I can certainly say that reclamation works in Italy have had a very remote application. Already pre-Roman peoples, such as the Etruscans, dedicated themselves to reclamation works. And these had a particular impulse in the glorious epoch of Rome. When the power of Rome declined, the work of rehabilitating the land also stopped, and many of the works carried out were left in abandonment, so that already redeemed lands returned to the condition of marshy lands: so it was, for example, of the Pontine Marshes.

The reclamation works were resumed in the centuries from the 10th to the 15th after Christ, but they stopped in the 16th and subsequent centuries. But in the 19th century, and precisely in the second half of it, after 1860, that is, after the establishment of the Kingdom of Italy, there was a reawakening in hydraulic reclamation, a reawakening that accentuated in the 20th century and led to the current fervent activity, which will not stop - we are sure - until completely and happily completed works for all that part of the soil of the homeland that needs hydraulic reclamation.

3. - The extent of the Italian territory in which hydraulic reclamation works are either already completed or are being carried out or will have to be started is truly remarkable.

From a total of 310,000 sq. km, that is 31 million hectares, of the national territory, 2,400,000 hectares, that is more than the thirteenth part of the territory, have been, or are currently, or will be subject to the systematic, regular execution of major works of hydraulic reclamation.

However, I must note that, in fact, the extent of the national territory, which will indirectly take advantage of the hydraulic works carried out, is much greater than the extent mentioned above, the precise place of the hydraulic reclamation works. Many areas close to the hydraulically reclaimed areas portray and will reap considerable hygienic and agricultural advantages. So, in the broadest sense that I have already said we can give to the word reclamation, it is more important than the thirteenth part of the national territory benefited by the works of hydraulic reclamation: just as the healing of patients is beneficial, not only to them, but also at the hygienic level of the environment, of the society of which they are part.

In the aforementioned 2,400,000 hectares, the past, present or future object of hydraulic reclamation, this can be considered in fact already achieved, except only the execution of certain completion works, in round numbers for 1,250,000 hectares that is for just over half of the total 2,400,000 hectares, under construction or with the certainty of imminent start for 600,000 hectares, still being studied for 550,000 hectares.

The reclamation areas, in which the works are completed or are in progress or are about to begin imminently (for a total, according to what has been said, of 1,250,000 + 600,000 = 1,850,000 hectares), include, in addition to many minor, 48 of greater extent, for each one, to 10,000 hectares. Between these:
24 are between 10,000 and 20,000 hectares,
10 are between 20,000 and 30,000 hectares,
4 are between 30,000 and 40,000 hectares,
2 are between 40,000 and 50,000 hectares,
3 are between 50,000 and 60,000 hectares,
2 are between 60,000 and 80,000 hectares,
2 are between 80,000 and 100,000 hectares,
1 has an extent greater than 100,000 hectares.

Between 50,000 and 60,000 hectares are the Cremonese Reclamation Mantovana, the Great Ferrarese Reclamation, the Reclamation of the Marshes of the Royal Lakes.

Between 60,000 and 80,000 hectares are the Reclamation of Ravenna between Sillaro and Lamone, the Reclamation of Burana.

Between 80,000 and 100,000 hectares are the Renana Reclamation (86,181 hectares) and the Parmigiana Moglia Reclamation (82,396). The reclamation of the Veronesi and Ostigliesi Valleys exceeds 100,000 hectares with an extension of 117,976 hectares.

4. - As we can see, it is a great technical task in which the Nation is committed and also a great financial effort.

The implementation of such vast works is carried out both directly by the state and by consortia of land owners. And it is regulated by legislation which can be said to have started with a law from 1882 due to Alfredo Baccarini, and which culminated in the Consolidated Act approved with R D 30 December 1923 n. 3256, modified by some successive dispositions: D L 5 February 1925 n. 166, Legislative Decree 29 November 1925 n. 2464, Legislative Decree 7 February 1926 n. 191.

In the expenditure for the hydraulic reclamation works, to which the reported statistical data refers, i.e. for the reclamation works that present hygienic and economic advantages of prevailing social interest, the State contributes from 56 to 75% according to the cases, the Provinces to the extent of 10 to 12.50%. The rest is the responsibility of the owners of the land.

In the case of carrying out the reclamation by the consortium concessionaires, the State and Provinces intervene with their contribution, which is paid in several years, only after the work has been tested. To start the work, the Consortium must obtain the necessary capital with provisional financing. The provisional financing is then replaced with definitive financing, as the annual contributions of the state and provinces become liquid through partial and final situations.

On 1,250,000 hectares with hydraulic reclamation already achieved, this was implemented for 350,000 hectares directly by the State, for 900,000 by concessionary Consortia; on the 600,000 hectares of reclamation in progress or imminent start, 225,000 are in direct execution by the State, 375,000 are entrusted to Consortia; on the 550,000 hectares of reclamation still under study, 70,000 concern the work directed by the State, 480,000 the work of the Consortia.

The expense that is expected for the completion of the already ongoing reclamation, for the completion of the ongoing reclamation, for the execution of all the hydraulic reclamations not yet started is four and a half billion lire. The expenditure that has been made in the last five years was 1,100,000,000 lire, of which 400,000,000 lire for works in direct execution by the State, 700,000,000 lire for works under concession by the land owners. The forecast of future expenditure for hydraulic reclamation alone is therefore quadruple that which incurred in the last five years. To this expenditure we will then add, with a very considerable sum, what is needed for all the ensemble of subsequent works for agricultural, hygienic, road, building organisation.

5. - I said that it is a great technical-financial effort that is underway. It cannot be completed until more than a decade has passed. The results will also be very remarkable. It is enough, for example, to think that, for 350,000 hectares reclaimed in Upper Italy until 1922, it was calculated that the annual agricultural production rose from 138,000,000 lire before the reclamation to 1,050,000,000 lire after the reclamation, that is, from about 400 lire per hectare per year to 3000 lire per year. So from the 1,150,000 hectares underway and awaiting reclamation, we expect greater agricultural production for the amount of three to four billion lire per year, that is, for an amount that exceeds the annual sum that Italy spends abroad for purchase of wheat in the years of poorer local production.

This grandiose reclaiming task of Italy - which also extends to vast areas not in need of hydraulic reclamation, but suitable for agricultural reclamation, i.e. significant cultural intensification - will lead, in an appropriate number of years, to an increase of about 20,000,000 quintals of cereals per year and an unspecified but certainly enormous increase in all other agricultural products, such as sugar beets, fodder, grapes, hemp, tobacco, vegetables, fruit.

All of this will have a beneficial effect on the trade balance by reducing imports and increasing exports, and will ensure perennial income of hundreds of millions of lire per year for taxes and duties, so that the State will be largely compensated, not only in the increased national efficiency, but also in the figures of its balance sheet, the undertaking on which it started and the burden that today it bears.

6. - This intense reclaiming action, this willingness towards an arduous technical-financial programme is one of the aspects of our work, of our activity. Another aspect, which does not complete the picture of the Italian renaissance but which has a very high importance and which also has points of contact with the reclamation works, is that of the production of electricity. Allow a brief mention, even if it has an appearance of a digression from the theme.

Hydroelectric energy production has been in Italy since 1920 as follows:
year 1920 ..... Kw-hours 3,550,000,000
year 1921 ..... Kw-hours 3,450,000,000
year 1922 ..... Kw-hours 3,650,000,000
year 1923 ..... Kw-hours 4,650,000,000
year 1924 ..... Kw-hours 5,400,000,000
year 1925 ..... Kw-hours 6,200,000,000
year 1926 ..... Kw-hours 7,300,000,000
year 1927 ..... Kw-hours 7,800,000,000

They are not exactly numbers in their absolute value that are of interest, numbers that perhaps do not surprise much those who belong to Nations that have an industrial life of more remote origin or who have had the gift of richer hydraulic energy from nature. What interests, and cannot be overlooked, is rather the gradient of this function with time, the electricity produced: almost stationary in the years from 1920 to 1922, it rises in the following years with an average increase of over 800 million Kw-hours per year.

We combine this rapid increase in our efficiency in the hydroelectric field with the progressive work in the field of land reclamation. And we envision this condition of things without boastfulness, but with the conscious modesty of those who surely work for their future.

7. - Having the honour of talking about reclamation, or rather reclamation in Italy in front of this exceptional and high powered audience which is the International Congress of Mathematicians, I think I can, and perhaps even have to mention a topic that on the one hand is of essential technical importance in reclamation projects, while on the other hand it requires the use of mathematical analysis procedures for its study. It is of considerable importance, especially from an economic point of view, to proportion the drainage channels well, so that they are not deficient, which could also result in the very serious damage of flooding of land, nor are they excessively large, which would correspond to an unnecessary increased expenditure, already very large, for reclamation works.

The dimensions of the channels are usually determined by trying to predict the maximum flow rate that the individual channels will have to dispose of, or, what is the same thing, the prediction of the maximum flow rate per unit of area (hectare) of the zone served by the channel, which flow rate is called the udometric coefficient.

It is necessary, on this topic, to remember the names of Bocci, of Bucchi, of Brighenti, of Ventura, and of Pasini. The formula of Domenico Turazza published in 1879 was and is widespread in Italy, for the udometric coefficient ...

The formula and its consequences essentially reduce the flood wave in the elementary channels, as I said, to pure kinematics. The formulas avoid a fundamental fact that is connected with that of the outflow in the channels, the filling of them during rain, that is, the moderating action which, over the extent of the outflow, exercises the capacity of the channels.

This lack of correspondence between physical reality and the analytical framework cannot be remedied by retouching, however diligent, some of the elements of the formula. It is true, yes, that no physical fact we can presume to represent with full fidelity in the short summary of one or a few formulas. But we can however propose (and in many cases the purpose gives useful results) that the analytical processes, however imperfect, are, at least in their fundamental concept, in tune with reality. If this is the case, then the formulas obtained are susceptible of gradual improvements suggested by reason and experience.

If this is not the case, the formulas remain a conventional non-reassuring means of calculation.

The same remark of purely kinematic vision of the flood wave must be made to a graphic method that was developed in Italy by Poggi and in Germany by Frühling.

Similar observations were already made many years ago, in 1901, by Ettore Paladini, with regard not to reclamation, but to a situation substantially similar from the hydraulic side, that of city sewers.

Paladini rightly observed that the development of a flood in a network of sewage channels is to be considered, in its essential line, at each time interval as a balance between the amount of water that enters the network, that which comes out and that which finds its delivery in the same time interval. The principle is axiomatic: the water that enters the network of channels in a given time equals the sum of what comes out and what is retained in the channels at the same time.

It may seem strange that such an intuitive principle did not find application for sewerage networks before the statement made, as I said, in 1901 by Paladini. But even so that is what happened.

In 1904 Gaudenzio Fantoli, on the basis of the clear and elementary criterion set by Paladini, developed a rational calculation process for sewer networks.

Well: despite the physical analogy between sewers and reclamations, the rule of the udometric coefficient for assessing the flood flow has continued to dominate in the calculation of the reclamation channels.

A study dating back to a few years ago aims to extend the warning that Paladini set out for sewers to the reclamation case and which obviously has significance for all channel networks.

8. - This is, in its essential lines, the method of calculating the hydraulic operation of the networks of drainage channels, recently studied and proposed here in Italy and in tune with the lucid vision of the eminent Italian hydraulic scholar Ettore Paladini: a method whose exposure I believed that this brief talk on reclamation in Italy could rightly be introduced.

It could be observed, however, that it happened to me, with this, parva componere magnis. But I assure you that I do not think at all of raising the result of studies, however patient and conscientious, to that same level where we must place the wisdom of the men of government, the skill of the organisers, the perseverance of the farmers, and the tenacity of the workers. We pay homage to these noble virtues, that know how to transform wild lands and feverish swamps into fertile and healthy fields, into regions full of life and industry.

Last Updated April 2020