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Healthy soils are at the core of sustainable land and water management in Europe. They play a fundamental role in water infiltration, nutrient cycling, carbon storage, agricultural productivity, and climate resilience. When soils function properly, they regulate water flows, retain nutrients, support plant growth, and contribute to the stability of entire ecosystems. For this reason, soil protection is increasingly recognised as a strategic priority across European environmental and agricultural policies.
Although the European Union does not currently have a single binding Soil Framework Directive, soil protection is embedded within a range of policy instruments. It is addressed through agricultural sustainability frameworks, climate mitigation and adaptation strategies, biodiversity initiatives, and broader land degradation objectives. These overlapping policy areas acknowledge that soil degradation — including erosion, compaction, organic matter loss, and land sealing — weakens the capacity of landscapes to retain water and nutrients. As soils degrade, runoff increases, sediment transport intensifies, and the risks of downstream flooding and pollution rise.
The interaction between soil and water is particularly important. Soil structure directly influences infiltration capacity, runoff generation, water storage, root development, and nutrient retention. When soils are compacted or depleted of organic matter, their ability to absorb and store water declines. This leads to faster surface runoff, higher erosion rates, and reduced drought resilience. Conversely, well-structured soils enhance infiltration, stabilise sediments, and support more balanced hydrological cycles.
Natural/Small Water Retention Measures (NSWRM) are closely connected to these soil-related objectives. By improving vegetation cover, restoring small retention features, and slowing water movement across the landscape, such measures can reduce erosion, enhance infiltration, improve soil moisture retention, and support the stability of soil organic matter. In doing so, they strengthen the soil–water system and increase overall landscape resilience. Retention measures therefore contribute not only to water management goals, but also to long-term soil sustainability.
Within OPTAIN, soil–water dynamics are examined through integrated modelling approaches that simulate hydrological processes, sediment and nutrient transport, crop–soil interactions, and climate scenario impacts. By analysing how different combinations of measures influence soil moisture dynamics, erosion patterns, and long-term water retention capacity, the project provides a deeper understanding of how landscape interventions affect both environmental performance and agricultural productivity. The integration of field-scale and catchment-scale assessments allows for a more comprehensive view of how soil management and water retention interact under varying climatic conditions.
Understanding soil protection is therefore essential for interpreting the broader role of NSWRM. Strengthening soil health enhances water resilience, reduces degradation risks, and supports sustainable agricultural systems. Through integrated assessment, it becomes possible to clarify how soil-focused and water-focused objectives align within multifunctional landscape management.