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.
Impacts of climate change on agriculture have been predominantly analyzed by using biophysical and crop specific model applications. Vulnerability assessments which identify the vulnerability of regions with their farming systems are urgently required, because agricultural adaptations to climate change are related to regional specifics, and therefore research has to consider the regional level. Therefore sector- and system-specific approaches have to be developed. This paper presents the methodology of a vulnerability assessment for organic farming systems in the Brandenburg Region, which considers regional-specific climatic impact, as well as the regional-specific adaptive capacity. In this region, the cultivation and management of legume-grass swards have a key position, especially the climate change impact on legume symbiotic nitrogen fixation and nitrogen mineralization. Adaptation strategies of crop production systems include reduced soil tillage, which plays an important role also in organic farming systems (reducing soil erosion, improving water infiltration, reducing evaporation and improving soil structure, control of N-dynamics) are developed and tested by means of an action research approach.
One of the important parts of the final conference of ‘nordwest2050’ has been the scientific exchange sessions in the House of Science and the Industryclub Bremen. Contributions were based upon a call for papers from October 2013. The scientific committee received almost 100 abstracts where 36 were chosen for oral presentations and 15 for poster presentations (see overview tables below).
Four main topics were discussed in parallel workshops:
• Analysing Impacts and Assessing Vulnerabilities
• Designing and Testing Solutions for Regional Climate Adaptation and Resilience
• Implementing Climate Adaptation and Paths to a Resilient Future
• Resilience for Business: Climate Adaptation Challenge and Strategies of Sectors and Companies
Der Bericht ""Digitale Stadtstrukturkartierung –
Analyse der stadtstrukturellen Grundlagen und thermale Charakterisierung von Stadtstrukturen"" repräsentiert das REGKLAM-Produkt 3.1.2a. Er beschäftigt sich mit der Analyse der stadtstrukturellen Grundlagen unde der thermalen Charakterisierung der Stadtstrukturen durch eine satellitengestützte Analyse von Oberflächentemperaturen. Das Teilprojekt erhebt den Anspruch, Anpassungsoptionen an Überwärmungseffekte für die gesamte Modellregion abzuleiten. Aus diesem Grund erfolgt die Untersuchung zweistufig. Zunächst werden anhand der Stadt Dresden Detailuntersuchungen durchgeführt. Dies ist notwendig, da die Datenlage diese Detailuntersuchungen ausschließlich für die Stadt Dresden hergibt. Anschließend erfolgt eine Transformation der in der Stadt Dresden gewonnenen Aussagen in die Modellregion. Im Rahmen des REGKLAM-Teilprojektes 3.1.2 wurden bestehende Methoden zur Ableitung von Oberflächentemperaturen aus Fernerkundungsdaten angepasst und um neue Ansätze ergänzt. Dadurch wurde eine Grundlage zur Bewertung der klimatischen Situation im Stadtgebiet geschaffen.
Over the last decades, Fucus vesiculosus, an ecologically important macroalga in the German Baltic Sea, has shown a massive retreat from the deeper zones of its former distribution presumably due to low light co-acting with other potential stressors such as high temperature, fouling, and grazing. Global warming may increase abiotic as well as biotic pressures and exacerbate environmental conditions in coastal ecosystems. The present study focussed on the effects of single or subsequently combined stressors on survival and palatability of juvenile F. vesiculosus. Fucoid offspring were exposed to high temperature and/ or feeding pressure. Feeding preference of Idotea baltica was quantified in a pellet assay calculated as an odds ratio. High temperature significantly impaired the survival of juvenile fucoids. Neither single nor combined stress considerably influenced the feeding preference of I. baltica. Surprisingly I. baltica strictly avoided pellets with juvenile F. vesiculosus compared to adult F. vesiculosus. Avoidance tended to be less pronounced in juvenile fucoids previously stressed by high temperature. Obviously grazing does not induce anti-herbivore defence, but rather the young plants appeared constitutively well-protected against isopod feeding. These results contradict the prevailing opinion that juvenile F. vesiculosus is more susceptible to herbivore grazing than adult F. vesiculosus.
Der Bericht "Ex-post Analyse von Extremereignissen auf dem Gebiet der Landeshauptstadt Dresden" repräsentiert das REGKLAM-Produkt 3.1.1b.Der vorliegende Produktbericht umfasst eine systematische Ex-Post-Analyse der Kenngrößen Sommerhitze, Frostperioden, Starkregenereignisse, Sturm- und Hagelereignsse, Überflutungen sowie Grundhochwasser anhand vorhandener Beobachtungs- und Messdaten für den Betrachtungs-zeitraum (1961-) 1991-2010, je nach Datenlage, um Rückschlüsse auf bereits tatsächlich aufgetretene Ereignisse in der Region schließen zu können. Weiter zurückliegende Ereignisse wurden, soweit die Informationen vorlagen, mit dokumentiert.
In den letzten Jahren hat sich die öffentliche, wissenschaftliche wie auch politische Debatte über den Klimawandel und über die Folgen der globalen Erwärmung deutlich intensiviert: Von Seiten der Bundesregierung wird im Hinblick auf den Klimawandel an die individuelle Verantwortung der Konsumentinnen und Konsumenten appelliert.
Und in der Tat legen Ergebnisse der sozialwissenschaftlichen Umweltforschung sowie der Marktforschung nahe, dass der Klimawandel bzw. die Klimarelevanz von Produkten und Dienstleistungen für die Konsumentscheidungen privater Haushalte an Bedeutung gewinnt und dass auf Seiten der Verbraucherinnen und Verbraucher eine gesteigerte Bereitschaft besteht, regionale und klimagünstigere Angebote stärker nachzufragen. Vor diesem Hintergrund stehen im Zentrum dieses artec-papers klimawandelbezogene Veränderungen der Nachfrage und des Konsumverhaltens. Hierzu werden u.a. die Entwicklung der Umwelteinstellungen einerseits und die Preisentwicklung andererseits thematisiert.