Continental demo site

Berlin-Brandenburg, DE

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Prognosis

Berlin faces increasing drinking water challenges due to rising demand from population growth and more frequent droughts. An expected 40% reduction in summertime natural surface water runoff by 2040 further complicates water management, necessitating strategies to ensure sustainable water supply and mitigate the impacts of climate change.

Situation

The metropolitan Berlin-Brandenburg region in the north-eastern German lowlands has a relatively high surface area of rivers and lakes, but natural flow is low and increasing temperatures has led to higher evaporation rates and drought periods resulting in reduced river flows. The city of Berlin and its metropolitan region rely on groundwater as the drinking water production source. Treated wastewater is currently released back into the local freshwaters, resulting in a partially closed water management cycle within the city area. Brandenburg state has a higher reliance on water for agriculture and ecosystems. The rising pressure of climate change is impacting the natural water cycle.

Climate related issues

Water stress

Climate change is expected to cause more frequent drought periods, leading to decreased water availability.

Securing drinking water

Urban consumption of drinking water, industrial and agricultural needs, recreational use, and ecological requirements will compete for limited water resources, creating potential points of contention.

New policies required

The Masterplan Water outlines various measures and strategies to ensure a stable and sustainable water supply.

Key actions

We are supporting decision-making processes by calculating scenarios for water resource challenges and mitigation measures and their effects on surface water, groundwater, and drinking water by:

  • Applying simplified models to evaluate pollution inputs to surface waters used for drinking water production and scenarios of related measures.
  • Identifying the relationship between the ratio of bank filtration and groundwater abstraction rate from drinking water wells with detailed groundwater models.
  • Developing and conducting workshops with relevant stakeholders to support decisions on measures to address challenges of reduced water availability.

Relevant sectors:

Municipality

Authorities

Citizens

Water utilities

Industry

Nature conservation associations

Our ambitions

In the IMPETUS project’s continental demo site, our primary goal is to tackle water scarcity in a city with a semi-closed water cycle. By identifying gaps in the regional water cycle and developing future usage scenarios, we aim to model both surface and groundwater in detail.

Our efforts to simulate water balance scenarios are crucial in reducing uncertainties, supporting strategies, and conducting vulnerability assessments. Moreover, this project supports the creation of a comprehensive regional strategy for water management and climate adaptation, developed by local authorities, to position the region as a national model for effective water strategies and best practices.”

Nasrin Haacke, Kompetenzzentrum Wasser Berlin

The following ambitions have been set:
  • Simulate and map the regional water cycle and water balance (quantitative and qualitative).
  • Assess cross-sectoral, regional vulnerability of critical conditions in the local water cycle.
  • Define and assess scenarios for the development of water resources under future challenges and potential mitigation measures.
  • Assess the effect of reduced groundwater recharge rates with detailed groundwater models.
  • Preparation and realisation of several workshops for stakeholder engagement that supports decision making, incorporating results of modelled scenarios.
  • Development of citizen-centered criteria and indicators to enhance the transparency, comprehensibility, and effectiveness of water-related adaptation measures, informed by prior insights into decision-making processes and prioritization approaches.

Issues

Region-specific solutions

Integrated mapping and regional watershed modelling

The evaluation of future scenarios such as low flow periods in surface waters, reduced natural groundwater recharge or different discharge routes for treated wastewater, and their effects on water resources is crucial for authorities and water utilities in order to secure drinking water production and a sustainable management of urban water resources.

For this, different modelling approaches are applied in IMPETUS to assess regional water flows, critical shares of treated wastewater and surface water groundwater interactions relevant for drinking water resources. These efforts support decision making including prioritization of measures for the local water management plan “Masterplan Water”.

Our approach:

  • Development and application of simplified models to assess water quality and quantity changes in the semi-closed water cycle of Berlin.
  • Calculation of scenarios for reduced surface water flows and its effects on water ballances and shares of treated wastewater and stormwater runoff.
  • Detailed groundwater and surface water modelling for specific relevant issues in the water cycle (e.g. variability of bankfiltration shares and reverse flows in surface water stretches).
  • Visualization of detailed modelling results in easy understandable map views.

Stakeholder Workshops to Support Collaborative Water Management

A participatory format to assess and prioritize sustainable water-related measures.

To support ongoing efforts in sustainable urban water management, the Ecologic Institute—on behalf of KWB—is organizing a series of multi-stakeholder workshops. These workshops aim to bring together diverse perspectives, strengthen collaboration across sectors, and jointly identify effective and widely supported adaptation measures. Participants from public institutions, utilities, science, civil society, and local initiatives come together to reflect on existing measures, explore future challenges through scenario development, and co-create transparent evaluation approaches. Established formats help create an open and structured dialogue.

Key elements of the approach:

  • Focused discussion on selected water-related measures
  • Scenario-based exploration of future challenges and needs
  • Co-development of criteria and indicators to evaluate measures
  • Involvement of a broad range of stakeholders
  • Practical recommendations to improve transparency and acceptance
  • Workshop outcomes contribute to refining individual measures and support coordinated efforts toward more resilient urban water management.
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Water stress

The effects of water stress have been increasingly visible in Berlin. Residents and authorities are noticing reduced water levels in lakes and rivers, which are crucial for the city’s water supply.

This reduction impacts everything from drinking water availability to navigability of ships and ecological health. Summer months have brought more frequent water usage restrictions and advisories, particularly during heatwaves, as the demand for water spikes. Furthermore,Ā agriculture of surrounding areas (Brandenburg) is feeling the strain, with farmers facing irrigation challenges and reduced crop yields due to insufficient water supplies. These signs of water stress underline the urgent need for effective water management strategies in the region.

ā€œAddressing the intertwined challenges is essential for the city's future. Berlin must find innovative solutions to manage its water resources efficiently and equitably, ensuring that the city can thrive despite the mounting pressures.ā€

Issue

Berlin is grappling with an increasingly critical water situation, driven by the dual pressures of climate change and the planned phase-out of brown coal by 2038. As temperatures rise and longer drought periods occur, the city’s water sources are drying up just as demand reaches new heights. The growing population intensifies the strain, putting more pressure on an already stressed system.Ā 

Berlin relies heavily on riverbank filtration and groundwater recharge from surface water for its drinking water production. Consequently, reduced surface water flows during drought periods significantly impact the city’s water supply.Ā 

Adding to these woes is the impending closure of the nearby Lausitz open-pit mine. When the mine shuts down and stops pumping its groundwater into the River Spree, the amount of available water in the Spree river is expected to reduce significantly. As Berlin’s population continues to grow, the water demand is increasing. Furthermore, the settlement of new industries in the metropolitan area further increases the water demand and depletion of water resources. With all these challenges, usage conflicts will increase between water utilities, existing and new industries, farmers, waterways usage (shipping, tourism), and natural habitats in the region – all competing for their share of the limited water. The stakes are high, with water availability and quality at risk, threatening Berlin’s sustainability.Ā 

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Securing drinking water quality

The reliance on riverbank filtration for production of most of Berlin’s drinking water necessitates sufficient surface water quality.

Berlin’s semi-closed water cycle with wastewater treatment plants located upstream of water works becomes increasingly challenging, as shares of treated wastewater increase during low flow conditions and might exceed critical levels in the future, if no measures are taken.Ā 

ā€œChallenges posed by trace residues of pharmaceuticals in Berlin’s semi-closed water cycle will increase in the future due to climate change related effects such as substantially reduced surface water flows during prolonged drought periods, as well as increased demand and resulting increase of wastewater discharge.ā€

Issue

Berlin is producing its drinking water mainly via riverbank filtration, during which surface water infiltrates to drinking water wells installed nearby rivers and lakes. However, these surface waters are impacted by upstream discharges from wastewater treatment plants, which introduces a significant challenge as trace residues from pharmaceutical products and other micropollutants impact the water quality and some of these substances survive the bank filtration process.Ā Ā 

This semi-closed water cycle is further challenged, when surface water flows decrease during increasing drought periods and, subsequently, the share of treated wastewater increases. Recent drought periods during the summer resulted in river flows being only half compared to the long-time average, showing the relevance of the problem. Furthermore, flow of the Spree river (one of the two major rivers in Berlin) will further reduce in the future when the coal pit-mine in the Lausitz region south of Berlin will close in 2038 (see issue on water stress).Ā 

In addition, higher demand by industry and increasing population increases the amount of wastewater discharged, which will further increase the share of treated wastewater in Berlin surface waters. All these factors result in increasing challenges for the Berlin water works to ensure that the produced drinking water will sustain its high quality.Ā Ā 

Therefore, a sustainable management of Berlin’s water resources and development of strategies and measures to mitigate the challenges is essential. IMPETUS is supporting the mitigation of these challenges by modelling of scenarios regarding future developments of surface water flows, shares of treated wastewater, bankfiltration shares, as well as the impacts of selected mitigation measures on the water cycle.Ā 

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New policies required

New policies are required in Berlin to secure the water supply due to a growing population and the impacts of climate change, which are increasing the demand for drinking water and the occurrence of prolonged droughts.

The Berlin water system faces significant challenges from nutrient and pollutant influxes, coal mining consequences, and a notable decrease in groundwater recharge.Ā 

"Comprehensive and strategic planning is essential to address the challenges Berlin’s water resources are facing, ensure water supply sustainability, protect water bodies, and manage wastewater effectively."

Issue

The “Masterplan Wasser” is Berlin’s comprehensive strategic framework designed to address future water management challenges from population growth and climate change. It integrates multiple projects and analyses to develop robust strategies for securing drinking water supply, protecting water bodies, and adapting wastewater management. The plan incorporates population growth projections and climate change studies to forecast future water needs and wastewater quantities. Scenario-based risk assessments consider surface and groundwater conditions under various future scenarios, with three main sub-projects focusing on the effects of different water availability scenarios on Berlin’s water system by 2050. 

The plan addresses critical issues impacting Berlin’s water management system, such as pollutants, nutrient influxes, and the effects of coal mining. The dry years of 2018-2020 highlighted the system’s vulnerability, with severe droughts demonstrating the urgent need for reliable minimum water flow to sustain the Spree and Havel river systems. Additionally, the city faces increasing groundwater demand coupled with decreasing recharge rates, further straining the water supply. The growing population exacerbates these challenges, driving higher water demand and increased wastewater generation. 

To mitigate these challenges, the plan includes over 30 concrete measures like implementing a low-flow concept for the Oberhavel River stretch and developing a trace substance strategy with Brandenburg. Significant investments are proposed to enhance water and resource protection, aiming to close knowledge gaps, minimize uncertainties, and develop adaptive measures for future challenges. These steps are essential to counteract the projected 40% reduction in summertime natural surface water runoff by 2040 and to handle climate change consequences. 

Completed projects have provided valuable data and models, while ongoing projects such as IMPETUS continue to refine strategies and assess new risks. The plan remains dynamic, adapting to new findings and ensuring long-term water security for Berlin and its surroundings, making it a crucial blueprint for addressing both immediate needs and long-term sustainability amidst evolving environmental and demographic pressures. 

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Extreme events

Reports from European Environment Agency indicate that over the past decades, Europe has been experiencing frequent and severe weather and climate-related natural hazards likeĀ droughts, forest fires, heatwaves, storms and heavy rain. Climate change will make these events even more intense and more frequent. The summer of 2024 was the hottest on record for Europe and globally. While up to recently the extreme events were not considered usual in Zemgale region, experience from few previous seasons raise precautions. In summer 2024, there were heaviest rains that Latvia has experienced since 1945.

The impact of various extreme weather events has been particularly pronounced in places with high population density, such as the city of Jelgava. The region’s flat topography and land surface elevation relative to sea level result in high groundwater levels, which place additional stress on the city’s drainage and storm water drainage systems.

Issue

In Jelgava, the main challenges from rainfall include high risk of flooding and damage to infrastructure during prolonged rainfall. The Lielupe River and its tributary floodplains, as well as low topography and high-water tables, make drainage and stormwater drainage systems difficult to operate. The extreme rainfall of July 2024 confirms that the existing sewerage system is inadequate to cope with such situations.Ā  In the region’s rural areas, the threats affect both settlements and villages and fertile agricultural land, which plays an important role in the region’s economy.

Storms are the second most pronounced weather extreme in the region and, although on average winds are not expected to change significantly over the 21st century, by the end of the century (relative to the period 1971-2000) there will be a greater number of both windless days and stormy days per year.Ā  In recent years, the Zemgale region has been severely affected by thunderstorms and storms that have brought heavy rainfall in the form of both rain and hail, destroying agricultural crops and damaging infrastructure in many places. Severe storms in summer and early autumn, when trees and shrubs are still in leaves, have caused severe damage.

Climatologists believe that the current extreme values will become the norm in the future, while extreme weather events will cause even more damage. Climate models also predict an increase in total annual precipitation over the 21st century, with an average annual precipitation in Latvia of 775.7 [±60.0] mm for minor, 806.5 [±72.8] mm for moderate and 814.2 [±79.7] mm for major climate change. Predictions foresee substantial increase in duration of heatwaves from climatic norm of 8 days to 16 [±8] days for minor, 22 [±9] days for moderate and 33 [±12] days for major climate change.

Forecasting extreme weather events is quite complicated task, as these events are characterized by short-term nature, they and spatially limited, and thus short warning times are operational. Measures for adaptation to climate change thus become essential by preparedness for more days with extreme temperatures and for more extreme precipitation events. Decision-makers and local authorities need data and information to make the necessary preparations in advance by adapting to the different scenarios and possible consequences.

Within activities of IMPETUS project, the Adaptation Pathways are elaborated for Zemgale region with particular focus on flooding occurrences from river spring floods and heavy rain events:

  • Adaptation pathways are developed to support in better management of river flood risks and heavy rain floods (flash floods).
  • Aimed to implement a set of measures for reducing the frequency and extent of flooded areas in both rural (agricultural) land and urban settlements.
  • In exchange with the stakeholders, adaptation options are identified, assessed and included in the pathways to increase adaptive capacity in Zemgale region.
  • Structural measures, e.g., upgrading of existing drainage and stormwater drainage systems, and aligning them with nature-based solutions for water retention in rural and urban areas, and cleaning of riverbeds are considered.
  • Non-structural measures for improving flood risk early warning system (EWS), increasing awareness of inhabitants and improving the efficiency of actions of competent authorities in case of floor risks are addressed.
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Flooding

Zemgale is a very flat region, located in a lowland area with a high density of rivers. The Lielupe River is characterized by its slow course, due to Zemgale’s flat topography and the low gradient of the riverbed. The height of the Lielupe floodplain does not exceed 1 m above water level. Downstream of Jelgava, the Lielupe River drops only 5-10 cm/km. The riverbed is much lower than the average level of the Baltic Sea.

Issue

Climate change in the Zemgale region by the end of the 21st century will have a major impact on the hydrological regime.Ā  One of the most significant changes will be increased precipitation: under a moderate climate change scenario, winter precipitation will increase by 24-38%, while under a significant climate change scenario, precipitation is expected to increase by as much as 35-51%. Maximum daily precipitation will increase by about 3-6 mm, in some places by as much as 10-12 mm. On a seasonal basis, the greatest increases in precipitation are expected during the winter and spring seasons, so that the risk of flash flooding increases significantly during the cool season, when evapotranspiration is not intense. Periods of high rainfall will alternate with prolonged droughts, which will have a particular impact on heavy rainfall events, increasing the frequency of flash floods. During heavy rainfall, short, localised flooding can be observed in both larger and smaller towns, as well as in flat rural areas.

One of the activities in Zemgale in the IMPETUS project is the improvement of the Flood Early Warning System using the HEC-RAS 2D model. This model simulates water flow in two dimensions, which is particularly useful for flood modelling and forecasting. The HEC-RAS 2D model uses two-dimensional Diffusion Wave Equations to calculate the water flow. The developed model performs 2D

Key Benefits of Using Such a Hydraulic Model

  1. Accuracy and Detail: The HEC-RAS 2D model provides high accuracy and detail, which is essential for flood risk assessment and management.
  2. Integration: The HEC-RAS 2D model can be integrated with other geographic information systems (GIS), facilitating data processing and visualization.
  3. Early Warning Systems: The model is crucial for the development of early warning systems, as it allows for the prediction of flood spread and impact, thereby helping to timely warn residents and take necessary measures.
  4. This solution automatically reads hydrological forecast data from the forecast system of the Latvian Environment, Geology and Meteorology Centre.

These model results are crucial for the operation of the Early Warning System, which uses this data to identify potential flood areas and prepare warnings at the property (cadastral unit) level.

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High temperatures

Record-breaking summertime temperatures have been recorded in the Netherlands in recent years. With global temperatures rising, such extreme weather events will occur more often, and for longer periods. Prolonged high temperatures, with warm nights as well as hot days, can cause heat stress* and related health issues, particularly among city populations.

*Heat stress occurs when the human body cannot get rid of excess heat and can impact wellbeing through conditions such as heat stroke, exhaustion, cramps and rashes.

"We want to enable municipality decision makers who are working on spatial developments to identify heat stress 'hot spots' and cool areas, analyse the future effects of climate change, and model the effect of different heat stress-reducing measures. The tool must provide them with an easy starting point to integrate heat stress risks in their projects."

Issue

Despite the cooling effect of the sea in the region of Zeeland, the growing risk of heat stress has become a concern.

Elderly and other vulnerable people are more impacted by the effects of prolonged heat, which can cause headaches, dizziness, insomnia and other health issues – even death. Excess temperatures also affect general comfort and liveability of cities. Water quality can be reduced, both for drinking and swimming, and infrastructure can be affected. Buildings and concrete surfaces trap heat, potentially leading to damage, and release it during the night, keeping temperatures warm.

During heat waves, it is important that everyone has access to a cool and comfortable place. Appropriate spatial planning can help to decrease and deal with heat stress.Ā Environmental factors like water bodies, trees, and shade have a major impact on stress caused by high temperatures. Therefore, planting trees, removing concrete surfaces, creating green roofs and cool spaces can improve our comfort and health. The IMPETUS Atlantic team is developing a digital tool to support regional decision making for city planning to address these needs.

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Flood risk

By 2050, sea-level within this region is predicted to rise by 15-40 cm, with more frequent extreme weather and more (severe) storms triggered by climate change. These changes will exacerbate the natural risk of flooding in the IMPETUS ‘Atlantic’ region, because it is surrounded by rivers and the sea, and is below sea level.

*Risk takes into account two aspects; the chance that an event will occur and the negative impact of such an event once it occurs. When there is a low chance that an event will occur, but its impacts are huge, the risk is still significant.

ā€œIn the Netherlands, an extensive system of dikes protects us against sea and river flooding. We have always put our faith in this defence and focused almost solely on flood prevention. However, pressure on our system will increase with climate change and rising sea levels. To adapt and maintain a safe living environment, we should develop other safety measures, like more robust spatial planning and contingency plans."

Issue

Rotterdam city, is located in Rijnmond – ‘mouth of the Rhine’. The Rhine river flows through this densely populated area and characterises the region. Protections such as sea dikes and storm surge barriers have been constructed to protect the region, but flooding still occurs.

People living in the city are accustomed to seeing smaller floods. The changing climate affects the interplay between rainfall, river levels and sea storms, increasing the flooding risk. Water levels could rise by a few metres, even in populated areas, with potentially massive impacts. 

Mitigation measures such as storm surge barriers reduce the chance that high water reaches the city, but to minimise the impact of floods when they do occur, adaptation strategies are also needed. A city that can adapt to be safe from floods must be carefully designed. How best to design such an adaptive city?

Critical infrastructure, such as hospitals and evacuation routes, must be accessible at all times. Planning how to best protect them, homes and lives is complex. Flood water behaves in a complex way and flood risks show strong spatial variations. The IMPETUS Atlantic team is developing a digital tool to support regional decision making for adaptive city planning. 

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Energy and waste water

To become climate-neutral by 2050, climate mitigation* efforts are crucial in our strategy for how to deal with climate change. Reducing our energy consumption is a significant mitigation step. In the Netherlands, 15% of energy is consumed in the Rijnmond area around the port of Rotterdam, in large part by a major petrochemical industry cluster.

*Climate mitigation encompasses measures such as technologies, processes, or practices that reduce carbon emissions or enhance the sinks of greenhouse gases.

Issue

The Rotterdam port petrochemical industry cluster is Europe’s largest. It consumes 70% of the Rijnmond region’s energy. A large part of this energy is wasted (64%, 203 petajoules). More than half of that energy is lost with wastewater. In addition, most energy processes within these industries rely on fossil fuels, which has a significant impact on the climate.

Energy use must be minimised and fossil fuels should be replaced by renewable sources if climate change is to be mitigated. Electrification of processes opens up the possibility to use more renewable energy and can greatly impact decarbonisation. Recovering wasted heat would significantly reduce energy consumption and is a first step towards a more circular industry.Ā 

Supporting industries in a transition towards climate-neutrality depends on identifying how best to reduce their carbon footprint without sacrificing production or performance. The IMPETUS Atlantic team is creating a digital tool that supports decision making about pathways towards an effective energy transition for EU industry.

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Eutrophication

Due to its fertile soils, Zemgale region in Latvia is characterised by an intensive agriculture where large-scale farming dominates. Agricultural activities are well developed and focus on the cultivation of crops.

During the last decade, the area of croplands in the region has increased along with application of high amounts of mineral fertilisers. Excessive loading of nutrients (nitrogen and phosphorus) lead to eutrophication of water bodies e.g., causing overgrowing of rivers, and thus putting a pressure on biodiversity and natural habitats.

Issue

Municipal wastewater effluent is another source of eutrophication in the region. Quite often performance of wastewater treatment facilities is not sufficiently effective to ensure complete purification of waste waters causing water pollution with nutrients. As the result the ecological water quality of the rivers in Zemgale region is mostly moderate or bad.

According to water quality monitoring data of 88 waterbodies located within the Lielupe River basin district, there are 53 waterbodies having significant disperse pollution load and 14 water bodies where point source pollution load prevails (Source: LEGMC, 2024).

Climate change related increase of temperature catalyses eutrophication processes in water bodies. Climate models predict continuation of the increase of temperature thus intensifying the symptoms of eutrophication in freshwaters. Therefore, along with reduction of use of fertilisers, improvement of municipal wastewater treatment facilities, application of additional measures to prevent nutrient runoffs from agricultural land and urban environment to water bodies is of pivotal importance.

Together with regional and local stakeholders in Zemgale region, IMPETUS project partners in Latvia are developing Zemgale regional climate change adaptation plan, that will highlight the possibilities and intention of implementation of nature base solutions, e.g., constructed wetlands in Zemgale region to reduce the nutrient leakages/runoffs, reduce eutrophication intensity and improve the quality of surface waters.