Soil moisture (CLIM 029) - Assessment published Nov 2012
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Climate change (Primary topic)
Typology: Descriptive indicator (Type A – What is happening to the environment and to humans?)
- CLIM 029
Key policy question: How are soil moisture and water retention capacity changing in Europe?
- Soil water retention is a major soil hydrological property that governs soil functioning in ecosystems and greatly affects soil management.
- There is no clear indication on past trends for water retention across the EU due to a lack of systematic and harmonised data.
- Water retention capacity and soil moisture content will be affected by rising temperatures and by a decline in soil organic matter due to both changes in climate and land management.
- Projections (for 2071–2100) show a general reduction in summer soil moisture over most of Europe, significant reductions in the Mediterranean region, and increases in the north-eastern part of Europe.
- Maintaining water retention capacity and porosity are important to reduce the impacts of intense rainfall and droughts, which are projected to become more frequent and severe.
Global surface soil moisture content based on remote sensing data
Note: SMOS provides a global image of surface soil moisture every three days; this map covers the period 8–15 June 2010. Yellow colours indicate drier soil surfaces; blue colours denote wetter conditions. SMOS can measure soil moisture levels to an accuracy of 4 % at a spatial resolution of 50 km — about the same as detecting a teaspoonful of water mixed into a handful of dry soil.
- Soil moisture and ocean salinity provided by European Space Agency (ESA)
There is no clear indication on past trends for water retention across the EU due to a lack of systematic and harmonised data. Several models have been used to assess soil moisture, but these are often reliant on secondary input data (i.e. observed precipitation and temperature). Direct observations of spatially explicit distribution of soil moisture across Europe are just evolving. Satellite-borne sensors, such as the European Space Agency’s (ESA) Soil Moisture and Ocean Salinity (SMOS) mission or EUMETSAT’s ASCAT Scatterometer, are able to make global observations of surface soil moisture (Figure 1). Such data, along with numerical modelling techniques, have the potential to be used in deriving composite maps of soil moisture levels down to a depth of 1–2 m, the so-called root zone. Thus, this information could help in assessing the impacts of climatic variations, including droughts, on for example ecosystem production.
Projections indicate greater droughts in some areas, which might lead to substantial reductions in summertime soil moisture, and marked increase in rainfall in others [i]. In particular in the Mediterranean area of southern Europe, soil water content is expected to decline, and saturation conditions are expected to be increasingly rare and restricted to periods in winter and spring [ii]. Harmonised time series data on relevant soil properties should be developed as should models to assess key parameters such as subsoil available water capacity and topsoil moisture levels. Satellite information should be integrated with representative observed data, also for projections.
[i] P. Calanca et al., „Global warming and the summertime evapotranspiration regime of the Alpine region“, Climatic Change 79 (2006): 65–78, doi:10.1007/s10584-006-9103-9.
[ii] José M. García-Ruiz et al., „Mediterranean water resources in a global change scenario“, Earth-Science Reviews 105, Nr. 3–4 (April 2011): 121–139, doi:10.1016/j.earscirev.2011.01.006.
Daily Soil Moisture of Europe
provided by Joint Research Centre (JRC)
Soil moisture and ocean salinity
provided by European Space Agency (ESA)
More information about this indicator
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