| 1. |
- Van Loon, Anne F., et al.
(författare)
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Review article: Drought as a continuum: memory effects in interlinked hydrological, ecological, and social systems
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Droughts are often long lasting phenomena, without a distinct start or end, and with impacts cascading across sectors and systems, creating long-term legacies. Nevertheless, our current perception and management of droughts and their impacts is often event-based, which can limit the effective assessment of drought risks and reduction of drought impacts. Here, we advocate for changing this perspective and viewing drought as a hydro-eco-social continuum. We take a systems theory perspective and focus on how “memory” causes feedback and interactions between parts of the interconnected systems at different time scales. We first discuss the characteristics of the drought continuum with a focus on the hydrological, ecological, and social systems separately; and then study the system of systems. Our analysis is based on a review of the literature and a study of five cases: Chile, the Colorado River Basin in the US, Northeast Brazil, Kenya, and the Rhine River Basin in Northwest Europe. We find that the memories of past dry and wet periods, carried by both bio-physical (e.g. groundwater, vegetation) and social systems (e.g. people, governance), influence how future drought risk manifests. We identify four archetypes of drought dynamics: Impact & recovery; Slow resilience-building; Gradual collapse; and High resilience, big shock. The interactions between the hydrological, ecological and social systems result in systems shifting between these types, which plays out differently in the five case studies. We call for more research on drought preconditions and recovery in different systems, on dynamics cascading between systems and triggering system changes, and on dynamic vulnerability and maladaptation. Additionally, we argue for more continuous monitoring of drought hazards and impacts, modelling tools that better incorporate memories and adaptation responses, and management strategies that increase social and institutional memory to better deal with the complex hydro-eco-social drought continuum and identify effective pathways to adaptation.
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| 2. |
- Di Baldassarre, Giuliano, et al.
(författare)
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Integrating Multiple Research Methods to Unravel the Complexity of Human-Water Systems
- 2021
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Ingår i: AGU Advances. - : American Geophysical Union (AGU). - 2576-604X. ; 2:3
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Predicting floods and droughts is essential to inform the development of policy in water management, climate change adaptation and disaster risk reduction. Yet, hydrological predictions are highly uncertain, while the frequency, severity and spatial distribution of extreme events are further complicated by the increasing impact of human activities on the water cycle. In this commentary, we argue that four main aspects characterizing the complexity of human-water systems should be explicitly addressed: feedbacks, scales, tradeoffs and inequalities. We propose the integration of multiple research methods as a way to cope with complexity and develop policy-relevant science.Plain Language SummarySeveral governments today claim to be following the science in addressing crises caused by the occurrence of extreme events, such as floods and droughts, or the emergence of global threats, such as climate change and COVID-19. In this commentary, we show that there are no universal answers to apparently simple questions such as: Do levees reduce flood risk? Do reservoirs alleviate droughts? We argue that the best science we have consists of a plurality of legitimate interpretations and a range of foresights, which can be enriched by integrating multiple disciplines and research methods.
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| 3. |
- Teutschbein, Claudia, 1985-, et al.
(författare)
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Drought hazards and stakeholder perception : Unraveling the interlinkages between drought severity, perceived impacts, preparedness, and management
- 2023
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Ingår i: Ambio. - : Springer Nature. - 0044-7447 .- 1654-7209. ; 52:7, s. 1262-1281
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Tidskriftsartikel (refereegranskat)abstract
- The future risk for droughts and water shortages calls for substantial efforts by authorities to adapt at local levels. Understanding their perception of drought hazards, risk and vulnerability can help to identify drivers of and barriers to drought risk planning and management in a changing climate at the local level. This paper presents a novel interdisciplinary drought case study in Sweden that integrates soft data from a nationwide survey among more than 100 local practitioners and hard data based on hydrological measurements to provide a holistic assessment of the links between drought severity and the perceived levels of drought severity, impacts, preparedness, and management for two consecutive drought events. The paper highlights challenges for drought risk planning and management in a changing climate at the local level and elaborates on how improved understanding of local practitioners to plan for climate change adaptation can be achieved.
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| 4. |
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| 5. |
- Teutschbein, Claudia, 1985-, et al.
(författare)
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Future drought propagation through the water-energy-food-ecosystem nexus : A Nordic perspective
- 2023
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Ingår i: Journal of Hydrology. - : Elsevier. - 0022-1694 .- 1879-2707. ; 617
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Tidskriftsartikel (refereegranskat)abstract
- Droughts can affect a multitude of public and private sectors, with impacts developing slowly over time. While droughts are traditionally quantified in relation to the hydrological components of the water cycle that they affect, this manuscript demonstrates a novel approach to assess future drought conditions through the lens of the water-energy-food-ecosystem (WEFE) nexus concept. To this end, a set of standardized drought indices specifically designed to represent different nexus sectors across 50 catchments in Sweden was computed based on an ensemble of past and future climate model simulations. Different patterns in the response of the four nexus sectors water, energy, food and ecosystem services to future climate change emerged, with different response times and drought durations across the sectors. These results offer new insights into the propagation of drought through the WEFE nexus in cold climates. They further suggest that future drought projections can be better geared towards decision makers by basing them on standardized drought indices that were specifically tailored to represent particular nexus sectors.
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| 6. |
- Tootoonchi, Faranak, et al.
(författare)
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Copulas for hydroclimatic analysis : A practice‐oriented overview
- 2022
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Ingår i: WIREs Water. - : Wiley. - 2049-1948.
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Tidskriftsartikel (refereegranskat)abstract
- A warming climate is associated with increasing hydroclimatic extremes, which are often interconnected through complex processes, prompting their concurrence and/or succession, and causing compound extreme events. It is critical to analyze the risks of compound events, given their disproportionately high adverse impacts. To account for the variability in two or more hydroclimatic variables (e.g., temperature and precipitation) and their dependence, a rising number of publications focuses on multivariate analysis, among which the notion of copula-based probability distribution has attracted tremendous interest. Copula is a mathematical function that expresses the joint cumulative probability distribution of multiple variables. Our focus is to re-emphasize the fundamental requirements and limitations of applying copulas. Confusion about these requirements may lead to misconceptions and pitfalls, which can potentially compromise the robustness of risk analyses for environmental processes and natural hazards. We conducted a systematic literature review of copulas, as a prominent tool in the arsenal of multivariate methods used for compound event analysis, and underpinned them with a hydroclimatic case study in Sweden to illustrate a practical approach to copula-based modeling. Here, we (1) provide end-users with a didactic overview of necessary requirements, statistical assumptions and consequential limitations of copulas, (2) synthesize common perceptions and practices, and (3) offer a user-friendly decision support framework to employ copulas, thereby support researchers and practitioners in addressing hydroclimatic hazards, hence demystify what can be an area of confusion.
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| 7. |
- Tootoonchi, Faranak
(författare)
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Reducing uncertainties in climate change impact studies through uni- and multivariate methods : A Nordic perspective
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Climate change poses undeniable impacts on hydroclimatic processes due to simultaneous effects of rising temperature and changing precipitation patterns. To quantify these impacts, simulations of climate variables are typically retrieved from climate models, which are then downscaled and bias-adjusted for a particular study site.The literature holds various methods for bias adjustment, ranging from simple univariate methods that only adjust one variable at a time, to more advanced multivariate methods that additionally consider the dependence between variables. There is, however, still no guidance for choosing appropriate bias adjustment methods for a study at hand. In particular, the question whether the benefits of potentially improved adjustments outweigh the cost of increased complexity, remains unanswered.This thesis primarily sought to provide an answer to this question by offering practical guidelines for the application of uni- and multivariate bias-adjustment methods in hydrological climate-change impact studies. To this end, the thesis includes a practice-oriented overview of copulas, one of the most widely used multivariate methods in climate-change studies. Furthermore, it presents an evaluation of two commonly used parsimonious univariate and two advanced multivariate methods. The assessment focused on their ability to reproduce numerous statistical properties of precipitation and temperature series, and on the cascading effects on simulated hydrologic signatures. The thesis culminates in a practical application of one bias adjustment method as part of a modeling chain to quantify future droughts. The results elucidate that all bias adjustment methods generally improved the raw climate model simulations, but not a single method consistently outperformed all other methods. Univariate methods generally adjusted the simulations reasonably well, while multivariate methods were favorable only for particular flow regimes. Thus, other practical aspects such as computational time and theoretical requirements should also be taken into consideration when choosing an appropriate bias adjustment method.
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| 8. |
- Tootoonchi, Faranak, et al.
(författare)
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Uni- and multivariate bias adjustment methods in Nordic catchments : Complexity and performance in a changing climate
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 853
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Tidskriftsartikel (refereegranskat)abstract
- For climate-change impact studies at the catchment scale, meteorological variables are typically extracted from ensemble simulations provided by global and regional climate models, which are then downscaled and bias-adjusted for each study site. For bias adjustment, different statistical methods that re-scale climate model outputs have been suggested in the scientific literature. They range from simple univariate methods that adjust each meteorological variable individually, to more complex and more demanding multivariate methods that take existing relationships between meteorological variables into consideration. Over the past decade, several attempts have been made to evaluate such methods in various regions. There is, however, still no guidance for choosing appropriate bias adjustment methods for a study at hand. In particular, the question whether the benefits of potentially improved adjustments outweigh the cost of increased complexity, remains unanswered.This paper presents a comprehensive evaluation of the performance of two commonly used univariate and two multivariate bias adjustment methods in reproducing numerous univariate, multivariate and temporal features of precipitation and temperature series in different catchments in Sweden. The paper culminates in a discussion on trade-offs between the potential benefits (i.e., skills and added value) and disadvantages (complexity and computational demand) of each method to offer plausible, defensible and actionable insights from the standpoint of climate-change impact studies in high latitudes.We concluded that all selected bias adjustment methods generally improved the raw climate model simulations, but that not a single method consistently outperformed the other methods. There were, however, differences in the methods' performance for particular statistical features, indicating that other practical aspects such as computational time and heavy theoretical requirements should also be taken into consideration when choosing an appropriate bias adjustment method.
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| 9. |
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| 10. |
- Tootoonchi, Faranak, et al.
(författare)
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Uni- and multivariate bias adjustment of climate model simulations in Nordic catchments : Effects on hydrological signatures relevant for water resources management in a changing climate
- 2023
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 623
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Tidskriftsartikel (refereegranskat)abstract
- Hydrological climate-change-impact studies depend on climatic variables simulated by climate models. Due to parametrization and numerous simplifications, however, climate-model outputs come with systematic biases compared to the observations. In the past decade, several methods of different complexity and dimensionality for adjustment of such biases were introduced, but their benefits for impact studies and accurate streamflow pro-jections are still debated. In this paper, we evaluated the ability of two state-of-the-art, advanced multivariate bias-adjustment methods to accurately reproduce 16 hydrological signatures, and compared their performance against two parsimonious univariate bias-adjustment methods based on a multi-criteria performance evaluation. The results indicated that all bias-adjustment methods considerably reduced biases and increased the consistency of simulated hydrological signatures. The added value of multivariate methods in maintaining dependence structures between precipitation and temperature was not systematically reflected in the resulting hydrological signatures, as they were generally outperformed by univariate methods. The benefits of multivariate methods only emerged for low-flow signatures in snowmelt-driven catchments. Based on these findings, we identified the most suitable bias-adjustment methods for water-resources management in Nordic regions under a changing climate, and provided practical guidelines for the selection of bias-adjustment methods given specific research targets and hydroclimatic regimes.
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