Drought and floods: Unipd tests ancient Roman hydraulics in the field

That of 2026 is shaping up to be the hottest summer recorded since 1992. A record certified by the latest Arpav data: in the months of June and July the regional average temperature reached 23.1 degrees, shattering the records of 2003 (22.7) and 2022 (22.7). The very high temperatures and the absence of rainfall in recent months have forced the Regione del Veneto to declare a regional state of emergency for water deficit with Ordinance no. 72 of 1° luglio 2026. The main critical issues include a 28% drop in rainfall with a deficit of 2.4 billion cubic metres of water, the flow of the river Adige reduced by 21% and the risk of saltwater wedge intrusion.

Faced with this unprecedented water crisis, can history teach us anything? And could the answer to this crisis come from the legacy of our past?

Centuriation: once upon a time, or still with us?

Once upon a time there were the Roman centuriations, drainage ditches and rural hedgerows, which for centuries shaped and protected the rural landscape of Padova. In particular, the Graticolato Romano extended across the area north-east of the city, between the present-day provinces of Padova and Venezia. Created as ancient hydraulic works (dating back to the 1st century BC), recently turned into heritage assets (with the Museo della Centuriazione in Borgoricco and a landscape observatory for the Graticolato), but also partly erased by urbanisation and intensive agriculture, today they are once again emerging as a concrete response to the climate emergencies of the 21st century.

This is the core of WatHer (Water Heritage in European Rural Mediterranean), the transnational cooperation project co-funded with 3 million euros by the Interreg Euro-MED programme in which the University of Padua is taking part, and which involves 12 partners from eight Mediterranean countries, coordinated by Politecnico di Milano, with the aim of recovering the “wisdom” of historic water management systems to strengthen the resilience of the territory. The principal investigator for the University of Padua is Professor Mauro Varotto who, together with researcher Tanja Kremenić from the Department of Historical, Geographical and Ancient Sciences, has focused the research on the municipal territories of Mirano and Borgoricco within the 200 square kilometres covered by the entire centuriation.

The “water trilemma” and the centuriation of Patavium

WatHer aims to develop and apply to the ditches and hedgerows of the centuriated countryside an eco-hydrological model capable of responding to the Mediterranean “water trilemma”, namely the three challenges to be faced in the near future: prolonged droughts and water scarcity, extreme rainfall and sudden flood risks, and degradation of water quality caused by pollution of the shallow aquifer. These three critical issues are closely interconnected and therefore require a joint approach if they are to be addressed.

«It is a matter of imagining for the future a “third centuriation”, says Mauro Varotto, geographer and project coordinator for the University of Padua, in continuity with but different from the previous ones: the first was mainly devoted to agricultural production, the second became a diffuse city with the warehouse landscape we know, the third must be a green-blue centuriation, an environmental and hydraulic infrastructure capable of facing the challenges of climate change. To achieve this, a new governance model is needed for these millenary water lines, now fragmented into myriad private properties with no control room.»

This portion of territory is particularly suitable for studying the “water trilemma”: the case study in Padova focuses on the network of minor drainage channels that characterises the historic centuriated landscape in order to highlight the disappearance over the last fifty years of many ditches and their associated tree-lined hedgerows, a phenomenon that has reduced the area’s capacity to mitigate floods and counter drought.

If the post-war paradigm shift responded to the logic of extending cultivated land, improving its productivity and implementing “barrier-free” mechanisation, such as removing hedgerows, today, in the face of increasing intense rainfall and prolonged periods of drought, recovering the hydrological concept linked to Roman centuriation is not merely a return to the past.

«GIS analyses by the Comune di Borgoricco, the symbolic heart of the centuriation, show that between 2008 and 2022 the ditch network shrank on average by about 2.4 kilometres per year and the hedgerow network, in the same period, by about 1.8 kilometres per year, emphasises Tanja Kremenić. Although the productive priorities of the decades of the economic boom have recently been joined by rules offering greater environmental protection, the loss is still continuing today. WatHer arises from this emergency and tests on a small scale the feasibility and benefits of reintegrating the ditch-hedgerow system, proposing cultural heritage once again as a hydraulic and climate resource.»

This analysis makes it clear that the heritage of Roman centuriation does not consist solely in the agrarian division into centuriae to allocate farmland among settlers, but reveals itself above all as an imposing and strategic work of hydraulic engineering and land reclamation. The orthogonal grid of roads and canals was designed above all to distribute water and encourage its outflow by following the natural slope of the plain, a skilful system that, precisely because of its effectiveness, has come down to us, draining excess water and channelling it as far as the Adriatico.

The WatHer project brings the ancestral knowledge of ancient surveyors into dialogue with the most advanced technological tools: LiDAR data and cartographic analyses in a GIS environment, and environmental monitoring sensors in the field, which will be used to develop action plans co-designed with local administrations and communities (the Comuni of Borgoricco and Mirano are associated partners in the project), with the technical support of the Consorzio di Bonifica Acque Risorgive.

The WatHer project put to the practical test

From September 2026, several pilot stretches of drainage channels will be identified, in which the project intends to intervene through the restoration of the integrated ditch-hedgerow system, the historic landscape of the Roman grid, enhancing its functions as a water collector, for climate mitigation and as an ecological corridor, by widening the ditch excavation and adding a tree-lined hedgerow with an anti-evaporation shading function. Over time, the rehabilitation of these elements into an integrated system will offer multiple benefits: it will help slow flood peaks, store water for aquifer recharge, phytoremediate pollutants with riparian vegetation before they reach rivers, reduce evaporation thanks to the shade provided by hedgerows, and create ecological corridors and climate islands for fauna as well.

Together with the other pilot sites distributed across Spain, Portugal, Italy, Croatia, Slovenia, Cyprus, Albania and France, the Padua experience will serve to demonstrate that, through the skilful management of the two-thousand-year-old traditional irrigation systems, it is possible to achieve multiple benefits: ensuring measurable ecosystem services, safeguarding water resources, preserving the beautiful landscape celebrated by Goethe and, it is hoped, also securing an economic return in the medium to long term. In this way, the centuriation leaves the museum and once again becomes a living landscape.