Quantifying and visualizing compounding and cascading drought impacts through network analysis and sequential pattern mining

Abstract:

Rather than being single events occurring across space and time, natural hazards often occur simultaneously or successively, resulting in compounding and cascading impacts. For instance, droughts and heatwaves often occur together (i.e. compound hazards) and can trigger secondary events such as wildfires (i.e. cascading hazards). Furthermore, their impacts compound (i.e. compounding impacts), interact and propagate like toppling dominos through socio-economical systems (i.e. cascading impacts).

Despite the advances in compounding and cascading hazards research, previous work has failed to address their impacts. This hinders the development of impact-based forecasting systems as this knowledge is crucial to predict future impacts. Hence, gaining insight into the interconnectivity between impacts can support adaptation planning and help to reduce the likelihood of negative consequences.

Here, a new methodology for quantifying and visualizing drought compound and cascading impacts is presented using the 2018/19 drought in Germany as a case study. We propose the use of network inference and data mining tools to unravel patterns by using an existing drought impact dataset. Based on co-occurrence analysis, the strength of compound impact patterns was quantified. Moreover, association pattern mining allowed the detection of the most common links among impacts, which were subsequently used for predicting cascading impacts.

Results demonstrate that the occurrence of compound and cascading drought impacts follow a pattern and do not happen by chance. This has important implications for impact mitigation, suggesting that the understanding of past patterns can help in the prediction of future drought consequences. Based on the generated information, efforts can be directed to reduce the initiation of impact interaction networks. Moreover, the series of visualizations used can support the communication of important aspects of drought impacts interactions, facilitating an effective and knowledge-driven response by those involved in drought risk management. The tools used here can also be applied to other hazard types or combinations of hazards. It is expected this work will encourage a more holistic approach to natural hazards impact research.