The study ‘Soil and Water in a Changing Environment‘ (June 2014), carried out on behalf of the Environment Directorate-General of the European Commission, gathers information on the dynamics between soil and water, focusing particularly on soil water retention (SWR).
Soil water retention capacity can be defined as the capacity of the soil to capture, store and/or release water. There is a need for detailed and systematic information on the effects that current changes in land use and increasing variations in precipitation and temperature have on this vital soil hydraulic property and on related components of the water cycle such as water runoff, percolation and infiltration.
Soil and water are two key resources that directly or indirectly affect our everyday activities and are closely linked through the capacity of soil to retain water. A better understanding of the underlining mechanisms and factors that influence soil water retention is important to ensure and enhance the long-term supply of ecosystem services that are dependent on soil and water. Consequences of changing retention capacities of soils together with the impact of changing weather patterns are already presently felt at European level, with some regions being particularly affected. In particular, the catastrophic floodings that recently occurred in 2002 and 2013 in Central and Eastern Europe, and in 2007 and 2014 in Western Europe, highlight the urgency to better consider the impacts of our economic development on soil water retention capacity and the resilience of natural ecosystems.
The rise of food and biomass demands, for example, is likely to increase the pressure on water resources due to larger irrigation needs which, associated with more frequent drought events, can lead to fiercer competition for water resources in some regions. These extreme situations need to be identified and analysed, in order to extract valuable lessons that can be used to improve the EU-27 capacity of adaptation to changing environmental factors.
Soil water retention is a key soil property and significant component of the water cycle that greatly affects soil functioning and therefore its capability to deliver a range of ecosystem goods and services that are vital both for human activities (e.g. agriculture) and to nature (e.g. providing habitat for different species). It is defined to great extent by soil types, depending on its texture, organic matter content, structure or depth, for example. Moreover, also the type of land use and management practices significantly influence that capacity.
A brief analysis of current major threats to European soils is enough to see that those threats will usually have a close link with water retention. Erosion, for example, is much more likely to occur in dry soils. And higher compaction, or sealing, prevents water from infiltrating the soil and therefore decreases its retention capacity.
The results of the study – supposed to foster our knowledge on the relationships and feedback between water retention and other parameters at EU level – have been achieved by applying a modelling approach that allows quantifying the specific contribution of soil water retention capacity, based on past trends and projections of future conditions. Also the corresponding consequences to human activities of disrupting the links between soil and water need through urbanisation are presented.
More information: DG Environment / Soil