Abstract
Water management and environmental protection is vulnerable to extreme low flows during streamflow droughts. During the last decades, in most rivers of Central Europe summer runoff and low flows have decreased. Discharge projections agree that future decrease in runoff is likely for catchments in Brandenburg, Germany. Depending on the first-order controls on low flows, different adaption measures are expected to be appropriate. Small catchments were analyzed because they are expected to be more vulnerable to a changing climate than larger rivers. They are mainly headwater catchments with smaller ground water storage. Local characteristics are more important at this scale and can increase vulnerability.
This thesis mutually evaluates potential adaption measures to sustain minimum runoff in small catchments of Brandenburg, Germany, and similarities of these catchments regarding low flows. The following guiding questions are addressed: (i) Which first-order controls on low flows and related time scales exist? (ii) Which are the differences between small catchments regarding low flow vulnerability? (iii) Which adaption measures to sustain minimum runoff in small catchments of Brandenburg are appropriate considering regional low flow patterns?
Potential adaption measures to sustain minimum runoff during periods of low flows can be classified into three categories: (i) increase of groundwater recharge and subsequent baseflow by land use change, land management and artificial ground water recharge, (ii) increase of water storage with regulated outflow by reservoirs, lakes and wetland water management and (iii) regional low flow patterns have to be considered during planning of measures with multiple purposes (urban water management, waste water recycling and inter-basin water transfer). The question remained whether water management of areas with shallow groundwater tables can efficiently sustain minimum runoff. Exemplary, water management scenarios of a ditch irrigated area were evaluated using the model Hydrus-2D. Increasing antecedent water levels and stopping ditch irrigation during periods of low flows increased fluxes from the pasture to the stream, but storage was depleted faster during the summer months due to higher evapotranspiration. Fluxes from this approx. 1 km long pasture with an area of approx. 13 ha ranged from 0.3 to 0.7 ls-1 depending on scenario. This demonstrates that numerous of such small decentralized measures are necessary to sustain minimum runoff in meso-scale catchments.
Differences in the low flow risk of catchments and meteorological low flow predictors were analyzed. A principal component analysis was applied on daily discharge of 37 catchments between 1991 and 2006. Flows decreased more in Southeast Brandenburg according to meteorological forcing. Low flow risk was highest in a region east of Berlin because of intersection of a more continental climate and the specific geohydrology. In these catchments, flows decreased faster during summer and the low flow period was prolonged. A non-linear support vector machine regression was applied to iteratively select meteorological predictors for annual 30-day minimum runoff in 16 catchments between 1965 and 2006. The potential evapotranspiration sum of the previous 48 months was the most important predictor (r2 = 0.28). The potential evapotranspiration of the previous 3 months and the precipitation of the previous 3 months and last year increased model performance (r2 = 0.49, including all four predictors). Model performance was higher for catchments with low yield and more damped runoff. In catchments with high low flow risk, explanatory power of long term potential evapotranspiration was high.
Catchments with a high low flow risk as well as catchments with a considerable decrease in flows in southeast Brandenburg have the highest demand for adaption. Measures increasing groundwater recharge are to be preferred. Catchments with high low flow risk showed relatively deep and decreasing groundwater heads allowing increased groundwater recharge at recharge areas with higher altitude away from the streams. Low flows are expected to stay low or decrease even further because long term potential evapotranspiration was the most important low flow predictor and is projected to increase during climate change. Differences in low flow risk and runoff dynamics between catchments have to be considered for management and planning of measures which do not only have the task to sustain minimum runoff.
Content:
Regional Activities:
RADOST Annual Conference 2011 in Travemünde;
Research at Anchor;
Stakeholder Analysis;
RADOST-Workshop “Coastal Tourism”;
BSSSC/BALTEX Conference “Adaptation to Climate Change
on the Regional Level”;
Workshop “Baltic Sea and Baltic Sea Coast between Climate Change and Climate Adaptation”;
Mussel Workshop at the Institute for Baltic Sea Research Warnemünde;
International Activities:
Climate Change, the Science Policy Interface and Coastal Zone Management;
Workshops on Regional Availability of Climate Knowledge in the Baltic Sea Region
Content:
Regional Activities:
Workshop: Coastal Change as a Challenge for Society, Culture, and Spatial Planning;
RADOST on Tour: Baltic Sea Coast 2100 – On the Way to Regional Climate Adaptation;
Monitoring the Environmental Conditions in the Nearshore Area;
National Activities:
Outstanding Climate Adaptation;
International Activities:
RADOST in Exchange with Coastal Planners in the USA;
Short Film on Climate Change Adaptation in Germany, Poland,
and the Baltic States;
Publications:
Analyses of the Perception of Climate Change Along the
German Baltic Sea Coast;
RADOST Studies on Artificial Reefs
The survey of 4.000 companies in the metropolitan area of Bremen-Oldenburg in north-western Germany conducted by the University of Oldenburg as part of the ‚nordwest2050’ project in 2010 and 2012 showed that the economic importance of climate change is growing. The 2012 survey revealed that 38% of the companies polled already saw climate change as an important success factor for their company. In 2010, 31% of the companies surveyed said that they ascribed a “high” to “very high importance” to climate change for corporate success.
Content:
Regional Activities:
Looking Back on Five Years of RADOST;
RADOST Final Conference Takes Stock, Looks Ahead;
Looking Back: Comments on RADOST;
Bay of Kiel Climate Alliance Seeks to Make the Region a Climate Conscious Vacation Destination;
What’s Next after RADOST?
New Web Tool: “Northern German Climate Monitor”;
International Activities:
RADOST at the European Maritime Day;
Contributions wanted for ECCA Conference 2015;
Publications:
Communicating Adaptation to Regional Climate Change Impacts;
New RADOST reports;
Third Special Edition of “Coastal & Marine“
Content:
Regional Activities:
Science on Tour along the Baltic Sea Coast;
Climate Pavilion Schönberg Inaugurated;
New RADOST Partner: Hamburg University of Technology;
First Organic Mussels from Kiel;
International Activities:
Climate Change Impacts in the Baltic Sea Region: Assessment Report Provides Opportunity for Discussion;
Bottom-up Climate Adaptation Strategies towards a Sustainable Europe;
Transatlantic Exchange of Adaptation Measures;
Publications
Content:
Regional Activities:
RADOST: Baltic Sea Coast 2100;
Close Cooperation with Tourism Experts in the Future;
The Bay of Kiel Climate Alliance takes a new Direction;
National Activities:
Second Regional Conference on Climate Adaptation Communities in Climate Change;
International Activities:
National Adaptation Strategies in the Baltic States;
Exchange of Experiences with Practitioners in the USA;
Chinese Delegation Shows Interest in Coastal Research in Kiel;
RADOST and Baltadapt at Green Week and the UN Climate Conference;
RADOST at the Baltic Sea Days
Publications:
Perceptions and Activities regarding Climate Change on
the German Baltic Sea Coast;
Handbook „Climate Change Adaptation Strategies in the
Baltic Sea Region“;
New Edition of “Meer & Küste”;
Assessment of the Influence of Climate Change on Development Potential for Near-surface Geothermal Energy
Content:
Regional Activities:
The Bay of Kiel Climate Alliance Receives BMU Support;
Northern German Regional Conference;
New Website Provides Information about the Need for Coastal Protection;
RADOST GIS Presents Water Quality Indicators;
Coastal Research, Use, and Protection;
National Activities:
KLIMZUG Final Conference;
International Activities:
HELCOM Workshop in Warnemünde;
RADOST at the Dupont Summit 2012;
Publications:
Results of the 2012 RADOST Tour;
Integrating Climate Change into Economic Analyses under the EU Water Framework Directive
The vulnerability analysis of the food industry in the Metropolitan Region Bremen-Oldenburg is based on an examination of the supply chains of the poultry, pork, dairy and fish industries.