Stabilizing our Landscape Water Balance

A balanced landscape water balance is fundamental for healthy, resilient ecosystems, ensuring water availability for both humans and the environment, and enhancing nature's resilience to extreme weather events. However, climate change, intensive land use, and significant alterations to natural river and floodplain ecosystems are increasingly disrupting this balance.

In Germany, only 9 % of rivers and lakes are in good ecological condition, falling short of the European Water Framework Directive (WFD) goals. Simultaneously, pressure on soils and water bodies is mounting: drought periods are increasing, floods and heavy rainfall events are becoming more frequent, technical flood protection measures are reaching their limits, and irrigation demands are rising.

To effectively address these challenges, a fundamental shift is needed. From a currently drained landscape to a climate-adapted "sponge landscape" that retains, stores, and gradually releases water.

The term refers to the natural processes of water distribution and storage within a landscape. Water moves through and is stored in soils, plants, rivers, streams, lakes, and the atmosphere, thereby providing the landscape with resilience against disruptions. The landscape water balance encompasses all components of the water cycle:

• Precipitation
• Evaporation
• Snowmelt
• Infiltration and soil moisture
• Groundwater recharge
• Runoff through rivers and streams
• Water withdrawals

A healthy, resilient water balance buffers climatic extremes, supports biodiversity, and serves as natural infrastructure for flood and drought protection. Broadly speaking, water quality also plays a role, as it affects human uses (especially drinking water supply) and the living conditions for ecosystems.

Over many decades, the water balance has been systematically altered:

• Rivers have been straightened, deepened, or reinforced with embankments.
• Floodplains and wetlands have been separated from water bodies by dikes or drained.
• Reduced snowmelt in the low mountain ranges due to global warming.
• Urban and transportation areas have been sealed and compacted.
• Agricultural lands have been drained.
• Peatlands and fens have been drained and intensively farmed.

As a result, large parts of Germany have become extensively drained landscapes where water is not retained but rather quickly diverted. The consequences include lower groundwater levels, drier soils, and an increased risk of flooding during heavy rainfall.

The climate crisis exacerbates existing problems: summer droughts intensify soil and river desiccation and lead to declining groundwater levels. Simultaneously, the frequency of heavy rainfall and flooding is increasing. During intense rainfall, water is rapidly channelled through rivers into the seas. This water is lost to the regional water balance. This is also due to the fact that a significant portion of former floodplain areas is no longer available - whether due to dikes, sealing, or land-use changes. Consequently, flood damages are worsening.

Restoring Rivers and Floodplains

Intact floodplains store water and release it slowly during dry periods. Restoration improves water retention, promotes biodiversity, and contributes to climate protection through CO_₂ sequestration in soils.

Example: The dike relocation at Sandau Süd on the Elbe River creates 124 hectares of floodplain area and helps reduce regional flood peaks.

A near-natural river course with side channels, meanders, flood channels, and gravel banks enables diverse habitats and improves water quality. River restoration measures are therefore not only ecologically valuable but also make sense from a water management perspective. Additionally, extensive and ecologically oriented water body maintenance can do much to improve and preserve the condition of water bodies in the long term.

Example: At the Alte Nebel in Mecklenburg-Western Pomerania, a 200-meter-wide development corridor was created with positive effects on the water balance and biodiversity.

In cities, rainwater is often directly channelled into the sewage system. Through green infrastructure like green roofs or rainwater storage systems, water can be retained and utilized locally: a significant contribution to climate adaptation. This not only protects against flooding but also improves the microclimate in cities.

The climate-friendly sponge city

Source: Datenquelle: Monitoringbericht 2023 zur Deutschen Anpassungsstrategie an den Klimawandel

Example: Rainwater management becomes educational at the Freie Waldorfschule in Prenzlauer Berg, Berlin. The schoolyard was unsealed and greened. Under guidance, staff, parents, and students design and maintain the resulting open spaces to store rainwater.

Another option is the use of treated wastewater for maintaining urban green spaces.

• Soil-conserving cultivation preserves the water storage capacity of soils and promotes groundwater recharge.
• Diverse crop rotations, adapted crops, and agroforestry systems prevent soil erosion and increase resilience to drought.
• Agricultural land management to promote water retention and reduce runoff (e.g., through keyline design).
• Rewetting peatlands reduces greenhouse gas emissions and enhances landscape moisture.

The need to adapt our landscape water balance extensively to climate change has been recognized and is a central component of the National Water Strategy and the Action Programme for Natural Climate Protection(ANK). Several funding instruments are available for implementing restoration and water retention measures:

• The Water Framework Directive (WFD) provides the legal framework for the ecological improvement of water bodies.
• The federal programme "Blue Ribbon Germany" promotes restoration on federal waterways.
• The National Flood Protection Programme can finance large-scale retention measures.
• EU funding such as the European Agricultural Fund for Rural Development (EAFRD) and the European Regional Development Fund (ERDF) support rural development projects.
• Funding for municipalities through the National Climate Protection Initiative
• Natural climate protection in municipalities, here module C5: Restoration of small water bodies within urban areas
• Funding guideline for the rewetting of ecologically significant peatlands (1000 peatlands)
• Information, activation, managing and support for measures to rewet peatlands (InAWi)
• Other ANK programs (e.g. KlimaWildnis, climate-adapted forest management). A complete list of the ANK funding programs can be found at: https://www.kompetenzzentrum-nk.de/foerderung/

The vision for the future landscape water balance is a sponge landscape: a diverse, structurally rich landscape that absorbs, stores, and slowly releases water. A functioning landscape water balance is not a luxury but a prerequisite for climate adaptation, sustainable agriculture, flood protection, and a habitable environment. It is the only way to counter the challenges posed by climate change, protect our water bodies, and preserve biological diversity.

• Create space for rivers and self-dynamic water body development.
• Retain more water in the landscape instead of quickly diverting it through adapted land management.
• Utilize synergies between flood protection, nature conservation, and climate protection.
• Consistently implement existing funding programmes and strategies.
• Provide targeted support to municipalities and regions through advice and expertise.

Example: Retaining More Water in the Landscape: Conservation tillage (instead of ploughing) offers several advantages over conventional agriculture. By avoiding intensive soil disturbance like ploughing, soil structure is preserved, reducing erosion and improving water infiltration and storage. Additionally, organic material such as plant residue remains on the surface, enhancing soil fertility and biological activity. This leads to a more stable soil ecosystem in the long term and can reduce the need for fertilizers and pesticides.

Further information:

• Water Body Restoration: Start | Federal Environment Agency
• National Flood Protection Programme | BMUKN 
• Blue Ribbon Germany – Homepage