Petreza: The Floodplain Attica Cannot Afford to Lose

The floodplain of the Rafina Megalo Rema stream; looking upstream. The trees punctuating the green thickets of Reed Cane and rushbeds are nearly all Salix alba, a rare riparian woodland stand for Attika (drone photo from: https://megalorema.gr/).

 Petreza: The Floodplain Attica Cannot Afford to Lose

Hidden between the towns of Spata and Pikermi, remains one of the last free-flowing streams in Attica. This is the main stem of the Rafina Megalo Rema, as if flows through part of the Mesogeia Plain, this is the Petreza floodplain. 

Along the river's main channel, as it exits the entrenched reach of the Attiki Odos Highway,  lies Petreza, one of the region's last natural river floodplains and arguably one of the most valuable yet overlooked landscapes for nature conservation in the Athens Metropolitan Area. Far more than a rare patch of open green space, Petreza is a living ecosystem that supports exceptional biodiversity.  Although parts of the area may benefit from legal protection (on paper that is...), this unique floodplain is now under imminent threat from a large-scale river engineering project that proposes to transform much of the natural river into a heavily channelized flood-control corridor. The project, costing just over 100 million Euros is now underway - buldozers tearing down trees... If implemented in its totality, the project could irreversibly alter one of Attica's last functioning river ecosystem landscapes.

Floodplains are the areas where rivers naturally expand during periods of high flow. Rather than being "unused land", they act as natural reservoirs, slowing floodwaters, storing carbon, filtering pollutants and recharging groundwater. Across Europe, scientists increasingly recognise that protecting and restoring floodplains is among the most effective and cost-efficient ways of reducing flood risk while simultaneously conserving biodiversity.

The Petreza reach represents one of the largest remaining floodplain systems of the Rafina Megalo Rema, one of the few largely free-flowing rivers left in the Athens Metropolitan Aegion. Its riparian woods, wetlands and seasonally flooded habitats support remarkable wildlife, including around 150 recorded bird species, numerous freshwater fish, including lots of European Eels (Critically Endangered!), amphibians, reptiles (a populations of Stripe-necked Terrapins) and a museum-full of aquatic invertebrates. Several habitat types found here, including white willow (Salix alba) riparian woods mixed with rush beds (Juncus spp), are now exceptionally rare in Attica.

Beyond its ecological importance, Petreza provides essential ecosystem services for people. By remaining connected to the river, the floodplain naturally attenuates flood peaks before water reaches downstream urban areas. It also improves water quality, supports groundwater recharge and contributes to local climate regulation during increasingly frequent heatwaves. These benefits are precisely why the European Union now promotes Nature-based Solutions as a cornerstone of modern water management.

Today, however, Petreza is a battle ground between the government-promoted project for flood control and environmentalists, including concerned scientists. My colleagues at HCMR have written technical letters asking for this project to stop. It must be re-designed as a Nature based Solutions project that will protect key natural areas such as Petreza. The conflict is over design and implementation of the proper flood-control infrastructure, we are not against a project, we strongly disagree with the kind of project. Scientists have expressed concern that disconnecting the river from its floodplain, removing riparian vegetation and replacing natural riverbanks with hard engineering structures (gabion held levees) will totally degrade ecosystem functioning, reduce biodiversity and compromise many of the ecosystem services that make the floodplain valuable. Instead of eliminating floodplains, current European practice increasingly favours working with natural river processes rather than against them. So our Greek project is anachronistic, poorly planned, haphazard, and plain stupid! 

The choice facing Petreza - and the Greek Government agencies that support this- is therefore much larger than a local planning issue. It reflects two contrasting approaches to flood management: one based primarily on traditional high-cost engineered channels, and another that combines flood protection with ecosystem conservation through Nature-based Solutions.

As climate change brings more intense rainfall and hotter summers to the Mediterranean, preserving natural floodplains like Petreza is becoming not only an environmental priority but also an investment in public safety and long-term resilience. Once these ecosystems are lost, they are extraordinarily difficult—and often impossible—to restore.

Saving Petreza means protecting one of Attica's last living river landscapes, ensuring that future generations inherit a river capable of supporting both nature and people.

After more than 30 years working in river and wetland conservation, I am convinced this project could have been designed very differently. Destroying one of Attica's last natural floodplains is a choice—not a necessity.

Visit the environmentalists website to find out more (https://megalorema.gr/). 

We at HCMR (Inland Waters) support the environmental campaign to STOP the engineering project under way on the Rafina Megalo Rema Stream.

The upper Petreza floodplain, looking upstream from a drone image in early spring. Newly leafed white willow (Salix alba) line the anastomosing stream banks, while extensive seasonally flooded rush meadows stretch beyond the stream banks in the floodplain. This exceptional mosaic of riparian woodland and wet meadow habitats is unique and survives here on a scale found nowhere else in the peninsula of Attika (drone photo by Emmanuil Sperelakis/HCMR 8th March 2019).

The upper part of the Petreza floodplain; drone photo looking upstream. Early spring photo shoing recently leaved Salix alba (green trees) and the extensive high thickets of reed cane (drone photo by Emmanuil Sperelakis/HCMR 8th March 2019).

The lower, last part of the Petreza reach near the Arionos Bridge, here looking down-river towards the Arionos road and the eventual confluence of the main-stem with the Valanaris tributary (drone photo by Emmanuil Sperelakis/HCMR 8th March 2019).

The lower, last part of the Petreza reach near the Arionos Bridge, here the river enters a shallow valley, in the distance the Etos Hill (drone photo by Emmanuil Sperelakis/HCMR 8th March 2019).

White willows (Salix alba) forming loose stands along the river (at center). This spot is near the upper part of the floodplain (Near the Pyrgos Petreza Winery, downstream of the Pekermi-Spata bridge). In late summer 2026 this stream-side dirt road was built and many trees were felled. Photo: Sept. 2026.  

Walking along the river after flood waters enter the fields and rushbeds.  Photo: late May 2026.

Much of the Petreza reach is thick with these towering reed cane thickets (Arundo donax). Photo: late May 2026.

In late spring the walk on the small road along the right side of the Petreza reach is wonderful. A naturalists paradise.  Photo: late May 2026.

The Petreza is an important hotspot for birdlife; being located right next the the Loutros Spata hotspot it hosts well over 150 bird species, including many rare migrants. One the threatened migrants is this Turtle Dove. Photo: late May 2026.

Fish abound in most parts of the Petreza reach of the river especially in the upper and mid floodplain areas. Eels are very common and they probably feed on these small schooling fishes; these being Rhodes Minnows (Ladigesocypris ghigii), translocated from Rhodes and now well established.  Photo by Antonis Lazaris. 

We know very little about the biodiversity of this area. One of Antonis Lazaris's students documented the existance of the Stripe-necked terrapin in the stream at the Petreza floodplain. 

The catchment of the river basin of the Rafina Megalo Rema stream. In red outline the main-stem strech known as the Petreza reach where the exceptional floodplain habitats are located (base-map from Karymbalis et al. 2021). 

Location map of the Petreza Flood plain area (map: sketch deliniation by S. Zogaris on recent Goole Earth images). 

A map of protected area designations in the immediate area. The yellow zone is Zone B2 of Moderate Protection of Landscapes and Archeological Sites (Z.O.E. Mesogeion). Part of the floodplain of Petreza is within this designation.

Petreza, the lower part of the main stem of the Rafina Megalo Rema stream is a distict water body, monitored by HCMR under EU policy mandate (WFD 2000/60). Currently its ecological status is assessed aat Moderate. 

Newspaper Headlines: Documento (Sunday, 26 July 2026): Flood Control Project Leaves Rafina Exposed to... Flooding.  Scientists and local residents highlight the risks and policy failures of the project on the Megalo Rema Stream. 

Resources

HCMR's recent statement on issue:

Assessment_of_the_Ecological_Significance_of_the_Petreza_Floodplain_Rafina_Megalo_Rema

In the News: 

https://www.efsyn.gr/periballon/1446984/sos-gia-kindyno-plimmyras-sti-rafina-i-proeidopoiisi-toy-elkethe-gia-to-megalo-rema/

Bibliography:

https://megalorema.gr/en/rafinas-great-river/

Karymbalis, E., Andreou, M., Batzakis, D.-V., Tsanakas, K., & Karalis, S. (2021). Integration of GIS-Based Multicriteria Decision Analysis and Analytic Hierarchy Process for Flood-Hazard Assessment in the Megalo Rema River Catchment (East Attica, Greece). Sustainability, 13(18), 10232. https://doi.org/10.3390/su131810232

European Environment Agency (2019). Floodplains: a natural system to preserve and restore. EEA Report No. 24/2019.

European Commission Joint Research Centre. Nature-based Solutions for Water Management.

Penning, E. et al. (2023). Nature-based solutions for floods, droughts and biodiversity: Do we have sufficient proof of their functioning? Cambridge Prisms: Water.

Papadaki, C., Dimitriou, E., Skoulikidis, N. et al. (2023). Regarding the river engineering project being implemented at Rafina Megalo Rema stream. Hellenic Centre for Marine Research.https://www.researchgate.net/publication/385420330_Regarding_the_river_engineering_project_being_implemented_at_Rafina_Megalo_Rema_stream_in_Greek

Zogaris S, Charmpila EA, Vukić J, Giakoumi S, Barbieri R, Zogaris D, Ašenbrenerová E, Viñuela Rodríguez N, Tarkan AS and Šanda R. 2023. Unnoticed introductions, a silent threat for biodiversity: island endemic Ladigesocypris ghigii (Actinopterygii, Leuciscidae) translocated to continental Greece. The European Zoological Journal, 90(2), pp.840-855.

Zogaris S, Papadaki, C., Stoumboudi, M. (2026, Aug.). Assessment of the Ecological Significance of the Petreza Floodplain (Rafina Megalo Rema River) and the Compatibility of the Proposed Engineering Interventions with European Water Resources and Flood Risk Management Policy (In Greek). Assessment_of_the_Ecological_Significance_of_the_Petreza_Floodplain_Rafina_Megalo_Rema

Our Collaborators at Universidade Federal Rural do Rio de Janeiro

Our collaborators in Rio! 

Part of the reasoning for our recent August trip to Brazil was meeting like-minded researchers. This time, we were hosted by Professor Karine Bueno Vargas and her husband Claudio Nuernberg Junior at the Federal Rural University of Rio de Janeiro (UFRRJ). Professor Karine spearheads biogeographical and landscape studies at the Department of Geography and is interested in our landscape assessment methodology - LAP index - and our use of indices for assessment, climate adaptation and for educational training. Karine is doing some fantastic work in promoting biogeography including such interdisciplinary applications. She is vice-president of the Ibero-American Society of Biogeography (Sociedad Iberoamericana de Biogeografía) and on the board of directors of the Brazilian Association of Biogeography (Associação Brasileira de Biogeografia). 

It was wonderful to visit the univeristy campus at UFRRJ at Seropédica, on the outskirts of Rio de Janeiro. This is definately one the largest university grounds in South America and features specialized research laboratories and extensive training areas, botanical gardens etc. Complete with huge open landscapes with much livestock and especially many horses! (Estamos no Brasil!). We did some birding one very rainy afternoon and also walked in the field the following morning. It was really fascinating to be able to see the campus, its artificial lakes and wetlands, meet students and opportuniteis for fruitful collaboration here. 

I present some snapshots of our short visit to - UFRRJ and our natural history trips nearby (in Rio and the surrounding coast). We really feel so much gratitude for being able to live such an experience. Being in Brazil was a dream come true for us.

Photos from the University 

Vassiliki with Karine and students at the lab. Note the Brazilian Neo-colonial architecture in the background.

Next to our accommodations at the very nice Hotel Escola - UFRRJ we had wonderful views of the school's horses and stables and the countryside. The Unviersity was founded in 1910 as a college for agriculture and veterinary medicine, establishing agricultural education in Brazil. These early roots have shaped its focus and direction ever since.

These are African oil palms creating an interesting cultural landscape. 

The capybaras are very friendly here. They are overlooking the Lake of Istituto do Agronomia; Lago do IA (which I though was.... Artificial Inteligence...IA in Brazilian). 

Lago do IA (22°45'31.6"S 43°41'41.7"W). The largest artificial waterbody on campus, a real hotspot for birds. Of course we suggested it as on on eBird and got it official. 

Huge roost of cattle egrets (garça-vaqueira) at Lago de IA. 

Of course, the ''flamingo-coloured spoonbill'' (colhereiro) - Roseate Spoonbill. 

White-faced Whisltling Ducks (Ireré), these we have seen in Africa too. 

Of course, all those nasty ticks (carrapatos) are handled by this bird, an immature Yellow-headed Caracara (carrapeteiro) on a sleeping Capybara.

In 11 days of travel in Brasil we saw only three wild mammal species and very few signs of wild mammals near habitation (could this be due to over-hunting?). But the Capybara is abundant, even in urban settings. Despite the ''scare'' associated with their ticks. 

The campus was full of parrots! This one is one of the commonest, the White-eyed Parakeet - Periquitão-Maracanã (Photo I took at further afield at Itatiaia). 

Nice to meet Brazilian students! 

The main building - Pavilhão Central - and surrounding landscape. The university has an area of approximately 3024 hectares, making it one of the largest such university ground in Latin America. On the right you see Lago de IA which we suggested as an eBird hotspot! (photo by Drone Carioca https://www.youtube.com/watch?v=OuwVOA8G8eo)

Rio De Janeiro

Spent just two rainy nights in Rio. Big marvellous city - want to go back!

Cristo Redentor! On the last day, the morning sun finally shone and we got this pic! This is an emblem of Rio - Christ the Redeemer; it was completed in 1931, an art-deco statue 30 meters proud on a mountain peak 700 meters high. Of course, it faces East.

Rainy Rio - the Center of Town. We found a fantastic restaurant here and also visited a bookstore.

First time in Copacabana...Everybody is here! 

 You must go for the sunset at Pedra do Arpoado.

Pedra do Arpoado.

Later, some yoga at Pedra do Arpoado (very stormy)

And the moon over Copacabana beach.

Further afield - River and Riparian Habitats (Paraty - Ubatuba)

Near Rio and Sao Paulo there is the Mata Atlantica area with a distictive semi-diciduous tropical forest (and with subtropical highlands). Many areas are easily accessible, some are important eBird hotspots. People are very kind and welcoming and very talkative and interested in what you are doing. The biodiversity in the streams and riparian zones is amazing.

Small creek at Fazenda Angelim at Ubatuba (23°23'38.0"S 45°03'54.1"W).

Catfishes, of the Corydorases, Subfamily Corydoradinae. Ubatuba.
 

The culvert bridge of Reinaldo Mateus (23°18'15.9"S 44°52'09.2"W). This is a definate problem for migratory fish dispersal. 

The Ubatumirim river (where the bridge was, above). Typical Mata Atlantica river.

The Ubatumirim river. 

Drizzle on the docks of the canal of Paraty.

Rio Itamambuca, southwards, on the coast (23°24'09.0"S 45°00'41.8"W). The Tropic of Capricorn is approximately at 23°26′ S of the Earth's equator. 

Lobster Claw Heliconia (probably Heliconia bihai) on the trail near hotel on the Itamambuca.

Rio Itamambuca; we stayed nearby for four nights. 

Itamambuca estuary (23°24'25.2"S 45°00'36.2"W).

Natural History on Lesvos! An ecotourism paradise?

Mid April 2026

It’s been three decades since I last toured the island of Lesvos. Vassiliki and I were here in July 1995 to map the wetlands of Kalloni and Gera Bays on contract with the Ornithological Society, for a project organized by the Greek Biotope Wetland Centre (EKBY). The report was an interesting exercise in identifying, delineating and organizing wetland conservation needs.

This time I am back on a survey of streams, conducting a rapid assessment of pressures on river water bodies. I am also keeping notes on birds, but I have severe lower back pain and am moving very slowly.

There are some things I want to say about the island, and especially about the reasoning behind promoting a “different” kind of tourism here. And generally saving the authentic character of this unique island. And specifically, Lesvos is particularly important for its ecotourism initiatives in Greece.

Firstly, the relative conservation status of the island’s landscapes: they are still largely intact, agro-pastoral, and in many places purely beautiful and authentic. Even the coastlines are well preserved. It is quite amazing. The island’s 300,000+ sheep help maintain a wonderful mosaic of agro-forested savannas, phrygana, pseudo-steppe, grasslands, rockscapes and heterogeneous maquis scrub, supporting a rich biodiversity of invertebrates, reptiles, and birds. Lesvos is also surprisingly wooded. There is no island in Greece with this extent of oak forest, but it is not just woodland—it is also the beautiful groves, dense and extensive pinewoods, rocky forested pastures, punctuated by jagged volcanic formations. It is a truly unique landscape, and all these habitats are widespread. The wider landscape is the issue here, its big and no hyperbole.

Secondly, the specifics of the biodiversity. The island holds two-thirds of all wetland area in the Aegean Greek islands. Unlike Chios for example, wetlands are everywhere and in many forms, primarily due to the island’s geology (impervious volcanic rocks) and topography (shallow bays, gulfs, and highly indented coastal plains) and wetness - the island is more northerly...closer to the Marmara and Black Sea! This spring has been particularly wet, and all wetlands were well flooded. Biodiversity, in all its forms, is rich both on land and at sea. I am not sure how well this has been studied, but for ichthyofauna we are still lagging far behind—and there are some very important freshwater fish species in the streams here. Sealife is interesting here (another long story). The asiatic component of the fauna also - Persian Squirrels! But little is catalogued, for example little is known about aquatic insects and stream faunas. Birds, however, are well studied.

Thirdly, in terms of natural history education and ecotourism identity, the island is among the richest and most enriching of the Greek islands, perhaps only rivalled by Crete and Corfu. I think better than Corfu at least (however both Corfu as is Euboea and Lesvos are all continental islands). Lesvos is the premier Greek island for birding and one of Europe’s best-known globally-distinguished birding destinations, with no fewer than three English-language birding guidebooks dedicated to it (i.e., Williams, Brooks, Dudley). The main “honeypot” area for birding is the small village of Skala Kalloni, located in the centre of the island next to its largest wetlands on the Bay of Kalloni. The island also hosts one of the best geological museums I have ever seen, including a unique thematic Natural History Museum exhibits - this at the Petrified Forest area, at its easternmost edge, in the windswept, ocean-like port of Sigri. In addition, the island has a dynamic university with several departments related to environmental studies, geography, and marine sciences. What an amazing place to build the University of the Aegean! 

All this sounds really positive, but is the island’s nature, its cultural landscapes, and its scenic beauty truly protected?

Well, as one of the birding guidebooks on Lesvos eloquently notes: “Nature conservation as we know it in Europe is not practiced here”... (Dudley, 2007). And unfortunately, although this does sound extreme, a radical statement for sure, it does have some truth to it, even in 2026.

So, what are the problems?

• Protected areas do exist but they are are not managed for biodiversity conservation. Biodiversity in itself is poorly inventoried or monitored (with the exception of birds- where a lot of citizen science comes into play). Many stream suffer from anti-flood protection schemes that tears down woodlands of Platanus and rich riparian habitats nearly at every major stream even within the protected areas. In the hills, the conservation is happening, forests are growing back (we must acknowledge this) but it is due to the paradox of beneign neglect. 

• “Benign neglect” is not enough! In Mediterranean landscape conservation, “benign neglect” refers to the passive protection of landscapes through the continuation of low-intensity traditional land uses and limited human intervention, allowing ecological processes and biodiversity patterns to persist without intensive management. In many Mediterranean regions, however, complete abandonment may eventually lead to shrub encroachment, increased wildfire risk, and the loss of semi-natural habitats historically maintained by grazing and small-scale agriculture. 

• The island is facing a major rural depopulation and farming-collapse crisis. Sustaining the “working, living village” must be a priority for landscape management and biodiversity conservation. Without grazing and traditional land use, this richly heterogeneous mosaic of landscapes will collapse. If this abandonment continues, that would mean future mega-fires, expansion of closed shrub cover, loss of microhabitats for species dependent on open land, and rapid biodiversity decline.

• Water and wetlands may be common landscape features, but they must be better protected. We say many infringements, drainage-degradation, roading, anti-flood works wrongly developed, garbage dumping, in-filling near roads, small tourist buildings in wet areas, fencing, etc.

• Ecotourism promotion is not enough; it requires proper care of facilities and consistent, keen upkeep. The island’s ecotourism infrastructure is in poor repair, signage is poor, trash everywhere, ugly but localized sprawl close and inside many wildlife hotspots.

• The scenic beauty and naturalness, currently maintained largely through benign neglect, are now threatened by two major forces: a) over-development and construction for low-key tourism (moslty holliday home and small hotel building and roading) outside designated settlement areas, and b) industrial wind turbine expansion (threatening the wild western part of the island; which by the way is mostly protected in extensive Natura 2000 sites).

Some snap-shots follow....

One of the many small wetlands, this one near Eressos in teh beautiful western part of the island

Messa Wetland (aka ''Derbyshire''); one of the signature landscapes of Kalloni Bay (Photo: https://www.lesvosgeopark.

Ruddy Shelduck are just fantastic to be around, this 'eastern bird' is one of the specialties of the island.

The Kalloni Salt Works are the largest and best wetland on the isalnd. Besides the industrial salinas teh area around is full of water meadows and other wetland habitat.

Marsh Sandpipers! 

Dalmatian Pelicans stopped over at Kalloni for a few hours in the morning. 

Messon Wetland with many Glossy Ibises! 

A group of spanish students near the well-sited hide at Alykes Kallonis near Agia Paraskevi.

A flight of ibises at Skala Kallonis.

An activist's map of developments on Lesvos. Focus on the ''Planning Stage'' proposals of Industrial Wind Turbine plants on the western part of the island (Αιολικά Άδεια Παραγωγής). Already there are just a few such plants- and they make a mighty impression on the landscape - in the heart of the GeoPark. If the planning stage with production approval proceeds (which I hope it won't) than the western part of the island will be one big industrial wind farm (source of map: "Συλλογικότητες υποδοχής στη Λέσβο της APIIDTT Οαχάκας Μεξικού, ο Νότος Αντιστέκεται» Ιούλιος 2023"; from repost on facebook group: https://www.facebook.com/aigilops) .

The island's Natura 2000 protected areas. Note there are few small reserves, this effort to create larger contiguous areas sometimes overshadows critically important smaller areas or areas very close to the large reserves. 

THE APRIL 2026 SURVEY

My rough trip itinerary (yellow lines) from 13th to 19th April 2026. Green spot, the base, Hotel Pasiphae at Skala Kallonis (About 600 km covered). 

eBird Hotspots and local sites visted during my tour. I only managed one day East of Skala Kallonis, I highly recommend this western part of the island. Totally unique.