Background

Water is the foundation for life on Earth, the blue planet. The existence and well-being of humankind depend on the availability of fresh water. Water bodies are habitats for countless creatures that interact in complex ecosystems such as river deltas and wetlands. Terrestrial ecosystems evolve with changes in precipitation, evaporation and the corresponding soil moisture. The movement of water, both in liquid and as ice, shapes landscapes through erosion, transportation and sediment deposition. River networks traverse our landscapes and form the main transportation routes for water and sediments.

Throughout history, people around the world have found ways to harvest water for everyday use. Water is an essential resource not only for direct consumption and personal hygiene, but also for food production through fishing, irrigation, livestock and industry. Households and communities everywhere have formed a variety of unique relationships with water that go beyond mere physical needs and often have cultural and symbolic significance. In parallel, societies have taken structural and non-structural measures to protect themselves from floods, whether through dams or by avoiding hazard zones. These hydro-social interactions are highly dynamic and responsive to changes in hydrometeorological conditions, land use, water management, society and infrastructure.

Extremes

Water extremes resulted in three quarters of all natural disasters in the first 20 years of this century, impacting over 100 million people annually. However, floods and droughts are not natural phenomena, but arise from complex interactions between the environment and human activities. These interactions lead to ever changing risk landscapes that we do not yet fully understand and, thus, are incapable of forecasting. Floods and droughts cause by far the greatest financial losses from weather-related disasters, around half a trillion euros in Europe alone over the last 40 years. Water extremes and their cascading and compounding effects are among the most influential and likely systemic risks to humanity. Currently, almost 800 million people do not have access to adequate and safe drinking water. Ensuring water security today and in the future is among the most important concerns of our society. Anthropogenic climate change, population growth, urbanization and environmental degradation are leading to more vulnerable people living in at-risk areas and reversing progress in risk reduction. If the average temperature is projected to rise by 2°C, global economic losses from flooding are expected to double, while drought losses in Europe could triple.

Europe, Germany and Brandenburg

Europe's climate is warming faster than any other region of the world. While the global average temperature is rising by around 0.2°C by decade, in Europe it is almost 0.5°C. The accelerated warming also has severe consequences for water resources and water extremes. Heatwaves occur more frequently and intensively, and extreme events such as droughts and heavy rainfall are increasing considerably. While regions in southern Europe and the Mediterranean are already frequently extremely dry, areas such as Germany will experience particularly serious changes.

The challenges in managing water as a resource are particularly evident in Brandenburg, as if illuminated by a flashlight: Low annual precipitation and sandy soils with low water storage capacity characterize the federal state, which is considered “water-rich and water-poor” for good reason. The disturbance of the water balance caused by anthropogenic climate change not only leads to a decreasing water supply in surface waters and groundwater, but also to consequences in agriculture and forestry as well as in the integrity of terrestrial and aquatic ecosystems. Furthermore, in the coming decades, large areas of southern Brandenburg will have to compensate for a massive water deficit caused by decades of groundwater pumping as part of lignite mining.