Etablierung einer kombinierten Hitze- und Starkregenvorsorge

• Introducing a combined approach of heat and heavy rain prevention

Neht, Alice Dorothea-Franziska; Kuhnimhof, Tobias Georg (Thesis advisor); Römer, Wolfgang (Thesis advisor)

Aachen (2020)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020

Abstract

Over the past two decades, scientists have recorded substantial climate change in Germany. (Munich Re, 2015; IPCC, 2012; CEC, 2009). There is a broad consensus in the scientific community that the cause of climate change is due to the release of manmade greenhouse gasesIPCC, 2016, p. 2). If mitigation efforts to reduce greenhouse gas emissions are not implemented, climate change will continue and may intensify. Climate change projects predict that extreme weather events will increase in number, duration and intensity. The rise in temperature will bring heatwaves and severe flooding (Kunz et al., 2017, p. 58; Kreienkamp et al., 2016, p. 3). Researchers are now turning their attention to how these extreme weather events will affect urban areas and their inhabitants. Policies aimed at mitigation efforts should be implemented to avoid the adverse effects of climate change on urban populations.This particular research focuses on the effects of climate change posed by cities and urban communities (UBA, 2016, p. 8; IPCC, 2012, p. 13). Cities are particularly susceptible to damage caused by extreme weather events (Dosch, 2015, p. 8; Colten, 2006, p. 731). Existing environmental concerns are intensified by climate change, for instance urban heat islands will occur in greater frequency increasing global warming (Rößler, 2015, p. 124). An increase in urban development contributes to insufficient drainage and run-off causing flash flooding during periods of heavy rainfall (Hackenbruch, 2018, p. 12; Braasch et al., 2013, p. 14). As we look ahead, action is necessary to minimize the damage caused by extreme weather in urban communities. This study speaks to the mitigation efforts of cities to minimize the damage caused by climate change. The study focuses on the consequences of heat and heavy rain to urban communities, and the mitigation strategies and policies aimed at minimizing those consequences. The research methodology based on the KOHISTA concept, which assesses the cost of heat and heavy rain mitigation efforts in urban communities based on the financial and human resources needed. The goal of this study is to evaluate the applicability the KOHISTA approach at the local municipal level considering legal, environmental and human factors. A comprehensive literature review has informed the applied theory and empirical case study, which builds upon the technical fundamentals of climate change research. The empirical case study includes the cities of Aachen and Munster in North Rhine-Westphalia. The investigation uses structured interviews, document analysis and geo-spatial data analysis. Current research on the included cities was taken into account (including Pyka, 2020; Hofmann & Schüttrumpf, 2019), however this research must be distinguished from previous studies. Hofmann & Schüttrumpf (2019) recommend the development of an early warning system in the case of heavy rainfall to improve current hazard prevention systems. Pyke (2020) argues for the implementation of heavy rainfall risk mitigation efforts in urban development. The target population of the KOHISTA study are the employees and managers in specialized municipal departments, as well as the local politicians in local cities and municipalities. The study demonstrates that extreme weather events and their consequences are tied to urban space and must be considered with other uses of urban space and local environments. Urban planning is critical in climate mitigation. Instruments of urban and regional planning were rarely used in the two cities of this study. Empirical evidence shows that the most important mitigation efforts are to space out urban development, reduce the degree of sealing, establish or secure fresh air corridors and create new water and green spaces. However, the expert interviews demonstrate a lack of knowledge in city municipalities about how a cohesive mitigation plan can be implemented administratively. The study is the first step in closing the information gap and further research is needed. The conclusion of the study focuses on the formal and informal urban planning instruments, the actors and the spatial level. There is an opportunity for urban and regional planning to serves as the foundation of the recommended structure. This work also suggests collaboration between municipalities. Further laws, recommendations and regulations have been identified which can serves as a jumping off point for municipal collaboration. This study identifies those actors who have already created heat and heavy rain prevention measures. These prevention measures incorporate elements of urban and regional planning, environmental considerations, civil engineering, water draining, urban transportation and city water supply. In addition to formal instruments, which is required as a bases for administrative action, informal instruments can also be used with KOHISTA. In the future, development plans, climate change concepts and departmental mission statements can anchor KOHISTA for the actors. These considerations enable the municipal administrations to communicate with the community and promote the acceptance of KOHISTA measures. In the future, a group of informal KOHISTA can include core municipal actors as well as those supporting roles of communication, hazard prevention and implementation measures. Inter-municipal forms of cooperation should also be established. To locate potential KOHISTA sites, review maps showing the thermal load and heavy rainfall values. Criteria developed in this thesis can be applied to begin an initial assessment on the applicability of KOHISTA. In conclusion, KOHISTA is a future-relevant concept therefore municipalities should incorporate this concept as a part of their climate change mitigation efforts.