THE PROBLEM OF WATER IN THE CISPADAN PLAIN: FROM DROUGHT TO MEDICANES
This discussion about Romagna’s regional challenges of droughts and cyclones is an extract from and an addendum to the original book, entitled "Vivere in Romagna sott'acqua" (Living in Romagna under Water), published in July 2022 by Osvaldo Contarini.
The Mediterranean has always been considered a rather calm sea and certainly less hostile than the oceans from a meteorological point of view. However, for about half a century, satellite images have shown around a hundred cyclonic formations originating from the southern part of the Mediterranean, sometimes with the typical appearance of a hurricane, complete with a cyclonic eye and counter-clockwise rotational movement, with winds equivalent to a Category 1 hurricane. Borrowing the term "hurricane" from English, a new word has been added to meteorological jargon: "Medicane" or Mediterranean cyclone (Hurricane).
The Mediterranean has always been considered a rather calm sea and certainly less hostile than the oceans from a meteorological point of view.
For nearly half a century, satellite images have consistently revealed approximately one hundred cyclonic formations originating from the southern Mediterranean region.
Their appearance mimics that of a hurricane - circular eye and rotational movement in a counter-clockwise direction - and packs Category 1 hurricane-strength winds.
Borrowing the term "hurricane" from English, a new word has been added to meteorological jargon: "Medicane" or Mediterranean cyclone (Hurricane).
Cyclone Ianos (September 17, 2020), originating from Libya, between Greece and Italy (source: Wikipedia).
In some of these cyclones, winds have reached the speed of a Category 1 hurricane, over 120 km/h (75 mph), and in one of them, the winds reached Category 2 strength, over 150 km/h (93 mph).
Saffir-Simpson Scale, based on the average one-minute wind speed at 10 meters above the ground level (source: Wikipedia).
The Saffir-Simpson scale, developed in 1971 at the National Hurricane Center in the United States, theoretically should be applied only to tropical depressions located in the Atlantic and the northern Pacific. Other systems are used for monsoons, cyclones, and typhoons in other parts of the world.
Tropical/Subtropical Depressions in the Mediterranean are typically located almost exclusively west of the island of Crete, but meteorologically, they are identical to hurricanes or cyclones in any part of the globe, typically occurring during the autumn period and rarely during summer.
Particularly rare atmospheric conditions are required for the formation of Mediterranean cyclones, with masses of warm and humid air over the sea colliding with cold air currents from the north, creating highly unstable atmospheric conditions that intensify as they move slowly northward with a counterclockwise rotation. Favored by the increase in sea surface temperature due to global warming, the typical Mediterranean cyclone lasts from one to five days, causing high storm surges and very intense rainfall. In contrast, the typical Atlantic hurricane causes much more damage due to its high wind speed.
The Cispadana area of Emilia-Romagna seems to deserve the name of "hydrogeological Achilles' heel" for being highly vulnerable to subtropical depressions that penetrate the Adriatic Sea. The diagonal position of the Apennine mountain range provides an ideal location for the persistence of these tropical depressions in this area, creating intense storm surges with a rise in sea level along the Adriatic coast and hindering river drainage. Rotating westward, the Mediterranean depression collides with the northeastern part of the Tuscan-Emilian Apennines, remaining there and pouring down the significant amount of water it contains.
During the two tropical depressions that affected Emilia, particularly Romagna, around May 2nd and 16th, 2023, it is estimated that at least 20 to 50 centimeters (8 to 20 inches) of rainfall occurred in 2-3 days. This is typically the amount of rainfall received in six months to an entire year in Aosta. Not surprisingly, floods and landslides occurred in at least 40 communities in the area, with overflow from at least 20 rivers and canals. Interestingly, the foothill areas were more affected by landslides and floods. In the plain region, specifically Bassa Romagna, both rivers and canals swelled, and canal overflow was more prevalent than river overflow.
There were many casualties, an incredible number of displaced individuals, and significant economic and ecological damage, which urgently call for awakening the responsible organizations for monitoring, maintenance, and prevention of such disasters. Unfortunately, these disasters are expected to increase in the future due to the profound changes in global atmospheric conditions.
Warning communities at risk of landslides and flooding remains an exceptionally important measure, and in this regard, the competent authorities, primarily the Prefects and Mayors, have made maximum efforts. Tropical depressions in the Mediterranean are increasing and unpredictable. Their impact on the Cispadana region of Emilia has repeatedly proven to be catastrophic, confirming that the title of my book published in 2022 represented a stark reality: "Living Underwater in Romagna."
It is indeed remarkable that Romagna, which serves as a hub for the distribution of river and surface runoff water, suffers from the opposite effect during the summer months due to water scarcity.
In my book, I suggested maximizing the conservation of freshwater and avoiding its loss into the Adriatic Sea. This can be achieved through the use of reservoirs or artificial lakes that can also serve as overflow outlets during Red Alert situations when water levels in rivers and canals threaten to cause flooding.
By constructing partial dams or weirs on rivers, it is possible to create intra-fluvial reservoirs from which water can be obtained for irrigation purposes. By building reservoirs adjacent to rivers and canals, expansion areas can be created in many low-lying areas of our region, providing the dual benefits of water conservation and raising the overall ground level.
These measures can contribute to mitigating water scarcity during the dry season and help manage excess water during periods of heavy rainfall, thus promoting more sustainable water management practices in the Romagna region.
The above diagram illustrates how incomplete dams or weirs (D) distributed along a river can create water storage reservoirs without obstructing the total flow in case the water volume increases, thus reducing the amount of water wasted into the sea. Suitable sluice gates (S) and conduits (C) can be added to retain or drain excess water into dedicated artificial reservoirs or expansion areas (G). Five centuries ago, Leonardo da Vinci brilliantly demonstrated to the people of Romagna how to achieve this with his "weir" or "Leonardian weir" or "Leonardian dam." Few people are aware that there are still two weirs/closures in the Senio River that form two upstream reservoirs. Initially built to supply water to the watermills’ canal, they continue to function as reservoirs for water conservation used for agricultural irrigation.
Tebano Weir (Castel Bolognese) on the Senio River. The foreground shows the partial weir or dam (2022).
San Severo Weir (Cotignola) sul Senio (2022)
Rivers with high embankments, canals, and ditches are constant features of the Romagna landscape, with elevated roads and farmland situated much lower. They represent the result of centuries of extensive land reclamation works in the marshy areas that were typical of the eastern Cispadana region. Unfortunately, this region still remains at significantly lower levels compared to the foothill areas south of the Via Emilia.
The Romans taught us that land reclamation work is never complete. Maintenance work, such as dredging canals and rivers, should be ongoing. Unfortunately, the canals are turning into ditches, and our rivers have transformed into wooded areas, with restrictions of their riverbeds and obstacle to the river flow.
The forest in the riverbed and floodplains of the Santerno River,
south of the bridge on Via Reale (SS 16 - 2019).
The maintenance of rivers and canals falls under the jurisdiction of various administrative organizations, each of [which believes] them convinced it is doing its best with the resources available to them. However, they have not been able to achieve the ultimate goal of keeping the low-lying areas of Romagna dry and ensuring water availability in times of need. Swift water disposal and water preservation are two essential needs in Romagna that cannot be delayed.
Symptoms of this issue recur regularly every year. The diagnosis has been made, and the treatment is known and attainable. Prophylaxis would be ideal and has already been planned for a long time, yet it often remains stagnant for unknown reasons. In Veneto, expansion basins or reservoirs successfully prevented flooding five years ago when a significant amount of 700 mm of rain fell in just a few hours. In Emilia Romagna, less than 300 mm of rainfall caused extensive damage, complete chaos, and the regrettable loss of 15 lives.
It is particularly interesting to note that about 15 years ago, the Regional Administration allocated 190 million euros for the construction of 23 expansion areas (“casse di espansione,” in Italian). However, only 12 are currently operational, none of which are located in Romagna, the most at-risk area with annual flooding. Two expansion basins are under construction on the Senio River. The one in Tebano is not yet connected to the river, and the land for the second one has not yet been appropriately acquired. The Lamone and Santerno expansion basins are still awaiting completion after 15 years of planning.
“Il Resto del Carlino” newspaper, September 10, 2019
For those who oppose the concept of expansion areas, it is worth considering that the C.E.R. (Canale Emiliano Romagnolo) derives its water from the Cavo Napoleonico, a large expansion canal between the Po River and the Reno River, artificially created by Napoleon's engineers two centuries ago. Less than a week ago, the C.E.R. was at risk of overflowing. Its course was cleverly reversed using powerful pumps, utilizing the Cavo Napoleonico for its original purpose.
While everyone complains about low river water levels and profound climate changes, freshwater continues to flow into the sea, drought remains a constant in the summer, and excessive rainfall continues to flood Romagna.
There is still much work to be done to improve territorial resilience and prevent the catastrophes of May 2023. Preventive measures should start without delay in the low-lying areas of Romagna.
Copyright © (2023) Osvaldo Contarini All rights reserved