4. Where do floods occur?

Usually floods occur along river courses, coastlines and around lakes and dams. Flash flloods can happen almost anywhere. Around the world Floods can occur anywhere around the world.  Records are usually kept of floods that affect the lives of large numbers of people. Large floods along rivers flowing north in Asia or North America/Alaska and affecting huge areas but not many human lives are only reported for information. At the end of the 20th century, the largest floods impacting many human lives usually occurred in the countries of the tropical and equatorial belt, along the main river valleys, or countries with sea or ocean coasts, and very rarely in countries of the temperate belt. As a result of climate change, especially during the last decade, large-scale floods increased in the temperate belt in Europe in Germany, France, Poland, Serbia, the Czech Republic and Hungary, etc. (see Table 4). At the same time, the intensity, frequency and consequences of floods in countries in the tropical and equatorial belt increased, with a significant and ongoing impact on regions in the interior of these countries e.g., Pakistan, Thailand, the Philippines and Indonesia, etc. Climate change produced a combination of a number of flood causes: strong hurricane winds, heavy and continuous rainfall, high tides, unpredicted flash flloods, etc., in a number of countries (e.g. the Philippines, Indonesia, Pakistan, Thailand, Bangladesh, India, Japan, Bolivia, Argentina and Ecuador). In the countries of the temperate belt, the main causes of flooding are usually cyclones and strong winds bordering on hurricane level, etc., which in the past occurred only exceptionally.

At regional level The monsoon rains are an annual cause of seasonal catastrophic floodings, which, in combination with other hazards like landslides, cause numerous victims on a yearly basis (e.g. in the last five years: 60 victims in India in 2015, about 500 victims in India, 57 in Bangladesh and 30 in Nepal in 2017, more than 350 victims in nothern India in 2018, about 200 victims in India, 27 in Pakistan, about 100 in Bangladesh and Nepal in 2019 and , till to middle july 2020, monsoon floods and landslides killed at least 221 people in India, Nepal and Bangladesh (see Fig. 4),

At local level

At local level, floods affecting people’s lives occur most frequently where human activity has taken place without proper assessment, and with no planning or control. The media constantly show reports of high water sweeping through town centres because of illegal, uncontrolled construction, as well as images of huge areas of land flooded as a result of failure to build or maintain hydrotechnical installations. Floods in populated areas are usually the result of a lack of necessary maintenance of existing drainage systems, growth in settlements and low capacity of drainage systems. Floods occur where local authorities fail properly to meet their obligations in terms of construction, maintenance of hydraulic structures, the cleaning of river beds, logging and maintenance of drainage in settlements, etc.

Tab. 4. List of some of the bigger floods occurred in Europe in the decade  2010 – 2020