Periodic Reporting for period 4 - HydroSocialExtremes (Uncovering the Mutual Shaping of Hydrological Extremes and Society)
Reporting period: 2022-10-01 to 2023-03-31
More than 100 million people per year are affected by hydrological extremes, i.e. floods and droughts. Hydrological studies have investigated human impacts on droughts and floods, while conversely social studies have explored human responses to hydrological extremes. Yet, the dynamics resulting from their interplay, i.e. both impacts and responses, have remained poorly understood. Thus, current risk assessment methods do not explicitly account for these dynamics. As a result, while risk reduction strategies built on these methods can work in the short-term, they often lead to unintended consequences in the long-term.
As such, this project aims to unravel the mutual shaping of society and hydrological extremes. A combined theoretical and empirical approach is developed to uncover how the occurrence of hydrological extremes influences society’s wealth, institutions and population distribution, while, at the same time, society in turn alters the frequency, magnitude and spatial distribution of hydrological extremes via structural measures of water management and disaster risk reduction. To explore the causal mechanisms underlying this mutual shaping, this project developed three explanatory models as competing hypotheses about the way in which humans drive and respond to droughts and floods. These alternative explanations are being tested through: i) empirical analysis of case studies, and ii) global investigation of numerous sites, taking advantage of the current unprecedented proliferation of worldwide datasets. By combining these different methods, this project is addressing the gap of fundamental knowledge about the dynamics of risk emerging from the interplay of hydrological extremes and society.
The development of a dynamic approach for the study of change in hydrological risk is not only scientifically appealing, but also socially relevant. For instance, the UN Sendai Framework for Disaster Risk Reduction (2015) indicates “understanding disaster risk” as “Priority 1”. By unravelling the interplay of hydrological extremes and society, this project provides valuable insights about the way in which the different components of risk (hazard, vulnerability and exposure) continuously interact and change over time. Our results can support the development and making of policies and strategies reducing the negative impacts of drought and flood events, such as fatalities and economic losses.
As such, this project aims to unravel the mutual shaping of society and hydrological extremes. A combined theoretical and empirical approach is developed to uncover how the occurrence of hydrological extremes influences society’s wealth, institutions and population distribution, while, at the same time, society in turn alters the frequency, magnitude and spatial distribution of hydrological extremes via structural measures of water management and disaster risk reduction. To explore the causal mechanisms underlying this mutual shaping, this project developed three explanatory models as competing hypotheses about the way in which humans drive and respond to droughts and floods. These alternative explanations are being tested through: i) empirical analysis of case studies, and ii) global investigation of numerous sites, taking advantage of the current unprecedented proliferation of worldwide datasets. By combining these different methods, this project is addressing the gap of fundamental knowledge about the dynamics of risk emerging from the interplay of hydrological extremes and society.
The development of a dynamic approach for the study of change in hydrological risk is not only scientifically appealing, but also socially relevant. For instance, the UN Sendai Framework for Disaster Risk Reduction (2015) indicates “understanding disaster risk” as “Priority 1”. By unravelling the interplay of hydrological extremes and society, this project provides valuable insights about the way in which the different components of risk (hazard, vulnerability and exposure) continuously interact and change over time. Our results can support the development and making of policies and strategies reducing the negative impacts of drought and flood events, such as fatalities and economic losses.
This project aims to unravel the mutual shaping of society and hydrological extremes. A combined theoretical and empirical approach has been developed to uncover how the occurrence of hydrological extremes influences society’s wealth, institutions and population distribution, while, at the same time, society in turn alters the frequency, magnitude and spatial distribution of hydrological extremes via structural measures of water management and disaster risk reduction. The project is based on three main work packages (WPs). In WP1, we developed explanatory models as competing hypotheses about the way in which humans drive and respond to droughts and floods. In WP2, we performed empirical analysis of multiple case studies, including rural and urban areas in Bangladesh, Italy and South Africa. In WP3, we reviewed 134 global and free datasets allowing spatial (and temporal) analyses of floods, droughts and their interactions with human societies and developed a global investigation of numerous sites. The project also uncovered how inequalities contribute to turn floods into disasters and droughts water crises.
Unravelling the mutual shaping of hydrological extremes and society will contribute to move forward interdisciplinary efforts that cross boundaries between natural and social sciences. In the context of drought and flood research, interdisciplinary studies originated from the natural sciences (e.g. socio-hydrology) have given more emphasis to the complexity and variability of hydrological processes, while interdisciplinary studies originated from the social sciences (e.g. polical ecology) have given more emphasis to the complexity and variability of social processes. The concept of mutual shaping is intentionally used here to treat both hydrological and social processes with the same level of complexity.
This project has combined hazard-based with vulnerability-based methods to assess risk in a changing climate. For instance, while vulnerability-based methods often do account for diverse hydrological extremes, hazard-based methods for quantitative risk assessment focus on either drought or flood risk. The latter approach does not allow exploring some key dynamics of risk. For example, a number of recent studies have shown that socio-economic changes have been the main driver of increasing flood risk in Africa, while climate has (so far) played a smaller role. Yet, by focusing on flood risk alone, these studies did not consider the hypothesis that climate may have led, in some instances, to longer and more severe drought conditions, which in turn may have changed livelihood patterns, e.g. increased human proximity to rivers, and potentially led to greater exposure or vulnerability to flooding. In other words, it is still largely unexplored how sequences of droughts and floods, can make a difference in the dynamics of hydrological risk. Exploring the sequence effect, which has been one of the goals of this project, is crucial because of the clustering or persistence of droughts and floods, and the relationships between hydrological extremes and inter-annual signals of climate variability, such as El Niño Southern Oscillation. Also, climate research suggests that many regions around the world might experience, in the near future, more prolonged drought conditions followed by extreme flood events. This speaks for the relevance of the project results that have increased our understanding of how human response to drought might exacerbate the impact of flood events, and vice versa.
Lastly, the explanatory models developed in this project open up new opportunities for science. They contribute to ongoing efforts to modelling human adaptation to climate change. They have also been linked to global models, which did not account for the dynamic interplay of society and hydrological extremes, and been used to inform agent-based models. As such, this project has contributed to enrich the fundamental science underpinning water management in a rapidly changing environment.
This project has combined hazard-based with vulnerability-based methods to assess risk in a changing climate. For instance, while vulnerability-based methods often do account for diverse hydrological extremes, hazard-based methods for quantitative risk assessment focus on either drought or flood risk. The latter approach does not allow exploring some key dynamics of risk. For example, a number of recent studies have shown that socio-economic changes have been the main driver of increasing flood risk in Africa, while climate has (so far) played a smaller role. Yet, by focusing on flood risk alone, these studies did not consider the hypothesis that climate may have led, in some instances, to longer and more severe drought conditions, which in turn may have changed livelihood patterns, e.g. increased human proximity to rivers, and potentially led to greater exposure or vulnerability to flooding. In other words, it is still largely unexplored how sequences of droughts and floods, can make a difference in the dynamics of hydrological risk. Exploring the sequence effect, which has been one of the goals of this project, is crucial because of the clustering or persistence of droughts and floods, and the relationships between hydrological extremes and inter-annual signals of climate variability, such as El Niño Southern Oscillation. Also, climate research suggests that many regions around the world might experience, in the near future, more prolonged drought conditions followed by extreme flood events. This speaks for the relevance of the project results that have increased our understanding of how human response to drought might exacerbate the impact of flood events, and vice versa.
Lastly, the explanatory models developed in this project open up new opportunities for science. They contribute to ongoing efforts to modelling human adaptation to climate change. They have also been linked to global models, which did not account for the dynamic interplay of society and hydrological extremes, and been used to inform agent-based models. As such, this project has contributed to enrich the fundamental science underpinning water management in a rapidly changing environment.