Flood in Emilia-Romagna, what do porcupine dens have to do with the flooding of the river?

According to the law of 11 February 1992, the different animal species that create burrows on the banks of watercourses must be controlled differently.But it wasn't like that

Emilia-Romagna is dealing with bad weather over the past 48 hours he provoked flooding, landslides and floods, in particular between the provinces of Bologna and Ravenna.There are currently hundreds of displaced people, flooded homes without light or electricity and fields submerged by flood water.And while the operations of the Civil Protection and Fire Brigade proceed, many are wondering what the causes that led to this situation are.The attention of experts and technicians is focused in particular on the breakage of the banks of the Sillaro torrent, in the area between the municipalities of Massa Lombarda and Conselice, leading to the evacuation of residents within a radius of three kilometers from the point where the banks of the river torrent have collapsed.Daniele Bassi, mayor of Massa Lombarda, explained that according to the first findings carried out by the technicians, the embankment collapse which occurred in the Via Merlo area of ​​the city «could have been generated by the porcupine burrows, which are wider and deeper than those dug from other animals such as otters and foxes.We often think of otters, but porcupines also usually make dens in the banks of drains, canals and rivers.Then it is clear that there are other possible causes, primarily excessive water pressure."And the mayor of the municipality in Ravenna concluded:"Several teams are working constantly and without ever stopping, with trucks carrying gigantic stones, to be lifted and placed on site to solve the problem."The mayor also underlined that if other streams or rivers have not flooded, with the exception of the Sillaro, "it is due to the cleaning carried out recently".

The correlation between flooding and porcupine dens?The precedent in the Modena area

But what correlation is there between the flooding of streams and rivers and porcupine dens?There is a precedent.We have to go back to January 19, 2014 when, in the hamlet of San Matteo di Modena, in the Modena area, a flood occurred which caused the collapse of the right bank of the Secchia river, causing the flooding of vast agricultural areas and several inhabited centers, including the municipality of Bastiglia and that of Bomporto.During the technical investigations carried out after the flood, among the causes that caused the failure of the Secchia embankment, "the presence of burrows of animals with burrowing habits dug on the hanging embankments of the watercourses" was also mentioned, i.e. the dens of porcupines, badgers and foxes.After the flood, periodic monitoring of the banks of the Serchia river, the Panaro, the Naviglio canal, the Cassa Secchia and the Cassa Panaro began.

The census of dens after the flood of 19 January 2014

The monitoring revealed 900 critical issues, of which 600 deriving from animal dens.Afterwards, a sort of "census" was started to identify the species of animals that created active dens on the banks of the waterways in question and the prevalent presence of nutrias, foxes, badgers and porcupines emerged.In parallel, the «Hydraulic safety program» was approved as well as the «Plan for the numerical limitation of mammals with digging habits along the main river banks of the Secchia and Panaro Rivers» for the Porcupine species (Hystrix cristata), Badger (Meles meles) and Fox (Vulpes vulpes).

Interventions to limit fauna on river margins

According to the law 11 of February 1992, n.157 and subsequent amendments, however, the different animal species that create dens on the banks of watercourses could be controlled in different ways.

Consequently, interventions to control the species have been approved for each species.ISPRA and the Ministry of the Environment had given the green light to the animal control plan in question, giving authorization to hunt foxes using various techniques, including the aid of burrowing dogs, shooting with the aid of luminous front, capture by placing them in cages, while for the badger and the porcupine - which cannot be hunted - capture in cages and the movement of the animal to areas far from the river banks was authorised.

The fauna control plans in the river sections in the Modena area

In 2019, the council led by Stefano Bonaccini, after the controversies of environmentalists, approved the Fox control plan, with three main new guidelines on fox hunting:It is possible to capture foxes from 15 February to 30 June, interventions in the den are only possible by the relevant authorities or the local police and the killing of the fox during threshing is approved.However, the Istrice and Tasso control plan in the Secchia and Panaro river sections, again approved in 2019, which reads:«The analysis of the capture data highlights how the activity is more effective against the porcupine (20 animals captured) compared to the badger (8 specimens captured).Overall, however, thanks to the operating methods applied, it was possible to contain and in some cases resolve the problem of the impact of the species in question on the hanging embankments.The judgment of effectiveness is therefore concretely positive and it is considered appropriate to continue with the activities in order to maintain the current conditions and protect the hanging embankments of the hydrographic network of the province of Modena, with the aim of containing the risk of structural failures and consequent flooding, as happened for the Secchia river in 2014".The Istrice and Tasso control plan in the Secchia and Panaro river sections, again relating to the province of Modena, was renewed on 7 October 2022, and will be valid until 2024.

Is there a correlation between the flooding of the Sillaro torrent and the porcupine dens?

Is the flooding of the Sillaro torrent on 2 May 2023 really attributable to the presence of porcupine dens on the margins?It is possible that this is one of the contributing causes, but it is too early to say, because the surveys and necessary monitoring of the dens on the banks of the flooded stream have not yet been carried out - for obvious reasons.Furthermore, among the causes that led to the collapse of the banks of the stream, we must also take into account the prolonged period of drought that hit Northern Italy in recent months, not only in Emilia-Romagna.Furthermore, the level of rainfall, corresponding to what is normally recorded over a period of approximately 3 months, is highly likely to have influenced what happened.In short, the porcupine dens could be one of the causes that led to the flooding of the Sillaro stream, but further investigations will be necessary to understand how, if and to what extent they actually influenced the flooding of the stream.