<abstract xmlns="http://www.w3.org/1999/xhtml">There is public concern that large-scale disturbances to forest cover caused by insects and storm winds in the Bohemian Forest could intensify high water flows and enhance the expected flooding risks predicted in current regional climate change scenarios. We analysed stream discharge in Upper Vydra and Große Ohe, neighbouring catchments in the Bohemian Forest, the largest contiguous forested area in Central Europe. Upper Vydra, in the Šumava National Park, and Große Ohe (including the Upper Große Ohe headwater catchment in the Bavarian Forest National Park) are similar in size, but differ in land use cover and the extent of disturbed Norway spruce stands. Publicly available runoff and meteorological data (1978–2011) were examined using non-parametric trend and breakpoint analysis. Together with mapped vegetation cover changes, the results were used to address the following questions: 1) are there significant changes in the hydrological cycle and, if so, do these changes relate to 2) the extent and expansion of disturbance in forests stands and/or 3) altered precipitation dynamics and thermal conditions?We found no marked overall change in annual runoff or in annual or seasonal precipitation, but a significant increase in high flows in March. This overall trend related to the marked warming in late winter and early spring (+~4 K in April, p &lt; 0.01), irrespective of altitude and slope position. It significantly shifted the end of the snow cover period by more than three weeks to the beginning/middle of April depending on altitude, and intensified snow melt.In the Upper Große Ohe catchment, a significant decrease in catchment balance, the difference between the long term precipitation and runoff (–72 mm, 11%) was found when the loss of tree cover reached 30% of catchment area. Diminished evapotranspiration losses from severely disturbed stands increased groundwater recharge during summer and caused a significant rise in low flows in autumn.However, observed increases in late winter high flows were due to warming only. They could be further intensified by the increasing winter precipitation predicted under present climate change scenarios, and would therefore increase the risk of flooding at lower elevations.</abstract>

There is public concern that large-scale disturbances to forest cover caused by insects and storm winds in the Bohemian Forest could intensify high water flows and enhance the expected flooding risks predicted in current regional climate change scenarios. We analysed stream discharge in Upper Vydra and Große Ohe, neighbouring catchments in the Bohemian Forest, the largest contiguous forested area in Central Europe. Upper Vydra, in the Šumava National Park, and Große Ohe (including the Upper Große Ohe headwater catchment in the Bavarian Forest National Park) are similar in size, but differ in land use cover and the extent of disturbed Norway spruce stands. Publicly available runoff and meteorological data (1978–2011) were examined using non-parametric trend and breakpoint analysis. Together with mapped vegetation cover changes, the results were used to address the following questions: 1) are there significant changes in the hydrological cycle and, if so, do these changes relate to 2) the extent and expansion of disturbance in forests stands and/or 3) altered precipitation dynamics and thermal conditions?We found no marked overall change in annual runoff or in annual or seasonal precipitation, but a significant increase in high flows in March. This overall trend related to the marked warming in late winter and early spring (+~4 K in April, p < 0.01), irrespective of altitude and slope position. It significantly shifted the end of the snow cover period by more than three weeks to the beginning/middle of April depending on altitude, and intensified snow melt.In the Upper Große Ohe catchment, a significant decrease in catchment balance, the difference between the long term precipitation and runoff (–72 mm, 11%) was found when the loss of tree cover reached 30% of catchment area. Diminished evapotranspiration losses from severely disturbed stands increased groundwater recharge during summer and caused a significant rise in low flows in autumn.However, observed increases in late winter high flows were due to warming only. They could be further intensified by the increasing winter precipitation predicted under present climate change scenarios, and would therefore increase the risk of flooding at lower elevations.

Changes in runoff in two neighbouring catchments in the Bohemian Forest related to climate and land cover changes

Department of Physical Geography and Geoecology, Faculty of Natural Sciences, Charles University Prague, Albertov 6, 120 00, Prague, Czech Republic.

Bavarian State Institute of Forestry, Hans-Carl-von-Carlowitz-Platz, D-85354 Freising, Germany.

Bavarian Forest National Park, Freyunger Straße 2, D-94481 Grafenau, Germany.

Journal of Hydrology and Hydromechanics

This chapter is distributed under the terms of the Creative Commons Attribution 4.0 Public License.

There is public concern that large-scale disturbances to forest cover caused by insects and storm winds in the Bohemian Forest could intensify high water flows...

Changes in runoff in two neighbouring catchments in the Bohemian Forest related to climate and land cover changes

Published Online: Oct 20, 2015

Page range: 342 - 352

Received: Dec 08, 2014

Accepted: Jun 18, 2015

DOI: https://doi.org/10.1515/johh-2015-0037

Keywords
Runoff, Climate change, Forest disturbance

© 2015 Jana Bernsteinová et al., published by De Gruyter Open

This chapter is distributed under the terms of the Creative Commons Attribution 4.0 Public License.

Changes in runoff in two neighbouring catchments in the Bohemian Forest related to climate and land cover changes

Published Online: Oct 20, 2015

Page range: 342 - 352

Received: Dec 08, 2014

Accepted: Jun 18, 2015

DOI: https://doi.org/10.1515/johh-2015-0037

KeywordsRunoff, Climate change, Forest disturbance

© 2015 Jana Bernsteinová et al., published by De Gruyter Open

This chapter is distributed under the terms of the Creative Commons Attribution 4.0 Public License.

Keywords
Runoff, Climate change, Forest disturbance