Water retention (CLIM 029) - Assessment published Sep 2008
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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: ..
- Water retention capacity and soil moisture content will be affected by rising temperatures and by a decline in soil organic matter due to both climate change and land-management changes.
- 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 is important to reducing the impacts of intense rainfall and droughts, which are projected to become more frequent and severe.
Modelled soil moisture in Europe
Note: Left: example of a forecast of topsoil moisture (15 July, 2008), right: subsoil available water capacity derived from modelling data.
European Soil Data Centre (ESDAC), http://eusoils.jrc.ec.europa.eu/library/esdac/index.html (left); and European Flood Alert System (EFAS) http://efas.jrc.ec.europa.eu/ (right).
Modelled summer soil moisture (1961-1990) and projected changes (2071-2100) over Europe
Note: Simulated soil moisture by ECHAM5/T106L31 for the baseline period (1961-1990) (left) and relative changes in % under the IPCC A2 scenario (2071-2100) (right).
Simulated by the ECHAM5 global climate model. Calanca et al., 2006.
Calanca, P.; Roesch, A.; Jasper, K.; Wild, M., 2006. Global warming and the summertime evapotranspiration regime of the Alpine region. Climatic Change 79: 6578.
There is no clear indication on past trends for water retention across the EU except for local field data. However several models can be used to assess soil moisture, for both subsoil and topsoil. Figure 1, right shows the subsoil available water capacity derived from modelling data. Capacity is high in north-western and central Europe and low in parts of the Mediterranean. Forecasts of soil moisture trends (an example for 15 July 2008 is shown in Figure 1, left) show very wet topsoils in north-western and central Europe and dry topsoils in the Mediterranean.
Long-term past trend analysis of these modeled characteristics is not possible due to lack of information over a sufficient time-period for the main soil properties that are the input parameters for the models used.
Figure 2 presents summer soil moisture over continental Europe for the IPCC A2 scenario (2071-2100), compared with 1961-1990. The projections show a general reduction in summer soil moisture over most of Europe and significant reductions in the Mediterranean region, while the north-eastern part of Europe will experience an increase in summer soil moisture.
Daily Soil Moisture of Europe
provided by Joint Research Centre (JRC)
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