Floods: Causes, Course and Examples in Greece and Poland

Introduction

Floods are one of the most common natural phenomena that occur all over the world, including Europe, especially in Greece and Poland. In recent decades, floods have become more frequent and intense, which is related to many factors, such as climate change, urbanization, and errors in water resource management. The aim of this article is to discuss the main causes of floods, their course, and to provide examples of floods in Greece and Poland, especially those that had catastrophic consequences.

Floods pose serious threats to people, property and infrastructure. They can occur due to various causes, such as heavy rainfall, snow melt, extreme meteorological phenomena and problems related to human activity. In this article, we will also look at preventive measures and methods used to minimize the effects of floods.

Causes of floods

Floods can be the result of both natural and anthropogenic factors. Understanding the causes of floods is crucial to effectively prevent their effects and respond appropriately in crisis situations.

Natural causes

Heavy rainfall

One of the most common causes of floods is long-term and heavy rainfall. When the amount of rainfall exceeds the ability of the soil and rivers to absorb water, the excess water flows into riverbeds, which leads to them overflowing and flooding. Floods caused by heavy rainfall can affect both mountainous and lowland areas. In mountainous regions, severe storms can cause river levels to rise rapidly, which can pose a direct threat to residents and infrastructure.

In the case of Greece, precipitation is often associated with winter lows and summer storms, which are particularly devastating in urban areas such as Athens. In Poland, on the other hand, heavy rainfall is more common in the summer, when severe storms and heavy rain can cause local flooding, as has happened in many cities, especially in the south of the country.

Snow melting

Snow melting is another natural cause of flooding, especially in mountainous areas. In spring, when temperatures begin to rise, the snow accumulated in the mountains begins to melt, which leads to rising river levels. When this process is rapid, the water flowing down from the mountains can exceed the retention capacity of rivers and reservoirs, leading to flooding.

In Poland, floods related to snow melt are particularly common in the south of the country, in the Carpathians and Sudetes. In Greece, on the other hand, although this phenomenon occurs less frequently, it can be noticeable in the Pindos Mountains, especially in harsher winters.

Extreme meteorological phenomena

Hurricanes, typhoons and severe storms that lead to heavy rainfall pose a serious threat in many regions of the world. In Europe, such phenomena are rarer, but can have very devastating consequences. In Greece, especially in the summer, intense storms, so-called medicanes (subtropical cyclones), can cause flash floods, especially in coastal areas.

In Poland, extreme weather phenomena, such as violent storms and downpours, contribute to flooding, especially in the summer season. There are often situations in which rainfall is so intense that drainage systems are unable to cope effectively, leading to local flooding.

Geological phenomena

Landslides, mudslides and other geological phenomena can also lead to flooding. After heavy rainfall, especially in mountainous areas, landslides can occur, blocking the flow of water in rivers. When such a natural dam breaks, the accumulated water can rapidly flow down to lower areas, causing catastrophic flooding.

In Greece, such phenomena are common in mountainous regions such as Pindos, as well as on islands where the terrain is conducive to mudslides. In Poland, landslides are a problem especially in the Carpathians, where heavy rains can cause dangerous earth movements, leading to serious flooding.

Anthropogenic causes

Urbanization

Rapid urban growth and associated urbanization significantly contribute to increased flood risk. In cities dominated by impermeable surfaces such as concrete, asphalt or roofs, rainwater is unable to soak into the ground. As a result, there is increased surface runoff, which can lead to water accumulating on the streets and overflowing sewage systems.

In Athens, where rapid urbanization progressed in the 20th century, the lack of appropriate hydrological infrastructure means that heavy rainfall can quickly turn into flash floods. In Poland, this problem is particularly noticeable in large cities such as Kraków and Wrocław, where infrastructure development does not always go hand in hand with proper planning of drainage systems.

Improper water management

Incorrect planning or negligence in water resource management can significantly increase the risk of flooding. Inadequate river regulation, lack of rainwater retention and excessive drainage from urban areas can lead to serious hydrological problems. In Poland, many cities struggle with inefficient sewage systems that are unable to cope with large amounts of rainwater, leading to local flooding.

In Greece, these problems are also visible, especially in large cities, where the lack of appropriate drainage systems means that even small amounts of rainfall can lead to flooding.

Climate change

One of the most pressing issues that affects the frequency and intensity of floods around the world is climate change. As global temperatures rise, rainfall patterns are changing, leading to more extreme weather events, such as severe storms and heavy rains. In Greece and Poland, climate change is clearly felt, as confirmed by numerous meteorological analyses.

In Greece, intense summer storms are becoming more frequent, leading to flash floods, especially in upland and coastal areas. In Poland, changing rainfall patterns are causing floods that used to occur once every few decades to become more regular.

Flood course

Flood is a dynamic and complex phenomenon that can be divided into several stages, each of which is characterized by a different level of risk to people and the environment.

Preparation

One of the key elements that can help reduce the effects of floods is early warning. Many countries, including Poland and Greece, have rainfall monitoring systems that analyze meteorological data on an ongoing basis. Based on meteorological forecasts, it is possible to predict the risk of flooding and warn people about the approaching threat.

In Poland, there are warning systems that send text messages with weather alerts. In addition, messages about potential threats regularly appear in social media and in traditional media, such as radio and television. Similar systems are also used in Greece, and special emphasis is placed on quickly informing residents of areas at risk.

Eruption phase

When a river or other body of water exceeds its natural banks, the flood outbreak phase begins. Water floods nearby areas, and residents are forced to evacuate or take other measures to protect themselves from the incoming water. It is in this phase that the threat to human life and property is greatest.

In Greece and Poland, there are various emergency procedures that are initiated when a flood situation is declared. In cities at risk of flooding, local authorities organize evacuations, and emergency services take action to protect the population.

Full development phase

In this phase, the water reaches its highest level, which leads to the greatest destruction. Flooded houses, destroyed roads, broken bridges and destroyed infrastructure are just some of the problems that local communities and authorities have to deal with. In Greece and Poland, during such floods, rescue operations are carried out to evacuate residents and provide them with assistance at this critical moment.

Falling phase

After reaching the maximum level, the water begins to slowly fall, which does not mean that the threat is over. Often, after the water recedes, contaminants remain, and other threats are discovered, such as weakened buildings or soil contamination. Emergency services and law enforcement must respond quickly to minimize the risk to the health and lives of residents.

Reconstruction phase

The final stage of the flood is the reconstruction process, which can last for many months or even years. During this time, local communities and authorities must take action to rebuild the destroyed infrastructure and help the victims. In Greece and Poland, after each major flood, governments and local authorities release special funds to help rebuild the areas affected by the disaster.

Floods in Greece: Examples

Flood in Athens (2017)

In November 2017, Athens, and especially its western districts, were hit by a tragic flood. The city of Mandra was particularly hard hit, where heavy rainfall caused a rapid rise in the level of the Kifissos River. Water poured into the streets and flooded many houses and buildings, and at least 25 people died.

This flood exposed numerous shortcomings in the water management system in the region. The high level of urbanization, the lack of adequate drainage systems and the insufficient preparation of the urban infrastructure to handle such large amounts of water contributed to the tragedy.

Flood in Thessaly (2020)

In September 2020, Greece struggled with severe flooding in the Thessaly region, caused by storms associated with Cyclone Ianos. The city of Karditsa and surrounding villages suffered the most, being flooded. Hundreds of people had to leave their homes, and the material losses were enormous. Previously unusual for the Mediterranean region, the cyclone is becoming an increasingly common feature of the climatic landscape of the region, demonstrating the impact of climate change on the occurrence of such extreme events.

In response to these floods, Greek authorities have taken action to improve flood protection infrastructure and increase the capacity to respond to such events in the future.

Floods in Poland: Examples

The 1997 flood

One of the most memorable events in Polish history was the flood of the millennium in 1997. As a result of heavy rainfall in July 1997, especially in the Oder and Vistula river basins, a catastrophic flood occurred, inundating areas in Silesia, Lesser Poland and Lower Silesia. The cities of Wrocław, Opole and Kędzierzyn-Koźle suffered particularly badly, with thousands of homes, roads and bridges flooded.

Over 50 people lost their lives and the material losses were estimated at billions of złoty. This flood triggered a wave of changes in legislation and the water management system in Poland. Many cities, including Wrocław, invested in new flood protection systems to prevent similar tragedies in the future.

Flood in 2010

In June 2010, Poland again struggled with floods. Heavy rainfall, especially in Małopolska and Silesia, caused rivers such as the Vistula and Odra to overflow their banks. Hundreds of homes were flooded and thousands of people had to be evacuated.

This flood revealed many problems related to water management in Poland, especially in the context of the lack of adequate drainage systems in some areas of the country. Local and national authorities had to react quickly, and help came from both emergency services and volunteers who tried to help the victims.

Conclusions

Floods are a serious threat to both Greece and Poland. Climate change, urbanization and poor water management contribute to the increasing risk of flooding in both countries. In response to these threats, investments in flood infrastructure, better urban planning and early warning systems are needed to help minimize the effects of these catastrophic phenomena. In the context of ongoing climate change and the increasing frequency of extreme weather events, these countries need to continuously improve their flood prevention and response strategies to effectively protect their citizens and their property.