Predicting Present and Future Drought
Abstract

Abstract Author: M. Trnka, Z. Žalud, D. Semerádová, M. Hayes, M. Svoboda, P. Hlavinka, M. Dubrovský, D. Wilhite

Abstract Title: Expected Changes in Soil Moisture Regimes in two Central US and Central Europe

Abstract: Soils are an important control on water fluxes in the landscape and in many parts of the world act as the most important water reservoir mitigating the effects of rainfall variability. Soil moisture and temperature regimes are inherently more stable and quantifiable than their atmospheric counterparts and are essential in determining the environmental conditions of any region. They can also be used to demonstrate the impacts of climate change on a given region as they integrate not only the change of climate variables but also existing soil condition status and plant cover. In addition, the globally valid analysis of soil moisture and temperature regimes (http://soils.usda.gov/use/worldsoils/mapindex/smr.html) makes it possible to present a variety of consequences of climate change in terms of analogs. In order to easily estimate the soil moisture and temperature regime at a given site, or within a selected region, a software SoilClim was developed, tested, and applied in two markedly different regions of the Northern Hemisphere. SoilClim is based on an enhanced daily water balance model that incorporates interactions between the soil and atmosphere through a dynamic module of vegetation cover. In addition, a snow cover effect on the water balance (through freezing and thawing), as well as on the soil temperatures, is taken into account through the incorporation of a snow cover simulator. SoilClim was run both in Central Europe and Central US (High Plains) with the climatic data corresponding to the conditions expected under future climates taking into account two Global Circulation Models (ECHAM and HadCM) and assuming the B1 and A2-SRES scenarios with low and high climate sensitivity for time slices of 2025, 2050 and 2100. It was found that under the present climate only a fraction of the territory of Central Europe is situated within the dry tempudic soil moisture regime, with high drought risk being confined to a relatively small area (less than 1000 sq. km). However, under a changing climate, a ten to thirty fold increase of the areas with a high probability of dry events was noted as well as sharp reduction of perudic (very-wet) mountainous areas that are essential for sustainable river flow. The results of the simulation runs for the High Plains also indicate tendency to drier soil moisture regimes and eastward shift of pedocalc/pedalfer boundary. In case of SRES-A2 based scenarios the rates of these shifts were especially alarming taking place within decades rather than centuries. According to the SoilClim model, a new soil climate type that has not been recorded up to now at both case study areas might be expected at both regions between 2050 and 2100. The predicted changes in the soil climate regimes are closely related to drought impacts (e.g. decrease of crop yields, damage to forest stands, low streamflow and reservoir levels, etc.) or changes in the dynamics of key soil processes (e.g. rate of carbon sequestration or mineralization) and should be a part of a complex climate change impact assessment.

Acknowledgement: The work would not be possible without help and support of Dr. Ken Hubbard and Christy Carlson from the High Plains Regional Climate Centre who provided the data from AWDN network as well as excellent data support. We would also like to thank to Eric Hunt (NDMC) for his time and provided information.

The development of SoilClim and the international cooperation and data sharing was supported by the KONTAKT project ME 844. The study was supported by the Research plan No. MSM6215648905 “Biological and technological aspects of sustainability of controlled ecosystems and their adaptability to climate change“, which is financed by the Ministry of Education, Youth and Sports of the Czech Republic.