| 1. |
- Arheimer, Berit, et al.
(författare)
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The IAHS Science for Solutions decade, with Hydrology Engaging Local People IN a Global world (HELPING)
- 2024
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Ingår i: Hydrological Sciences Journal. - 0262-6667 .- 2150-3435.
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Tidskriftsartikel (refereegranskat)abstract
- The new scientific decade (2023-2032) of the International Association of Hydrological Sciences (IAHS) aims at searching for sustainable solutions to undesired water conditions - may it be too little, too much or too polluted. Many of the current issues originate from global change, while solutions to problems must embrace local understanding and context. The decade will explore the current water crises by searching for actionable knowledge within three themes: global and local interactions, sustainable solutions and innovative cross-cutting methods. We capitalise on previous IAHS Scientific Decades shaping a trilogy; from Hydrological Predictions (PUB) to Change and Interdisciplinarity (Panta Rhei) to Solutions (HELPING). The vision is to solve fundamental water-related environmental and societal problems by engaging with other disciplines and local stakeholders. The decade endorses mutual learning and co-creation to progress towards UN sustainable development goals. Hence, HELPING is a vehicle for putting science in action, driven by scientists working on local hydrology in coordination with local, regional, and global processes.
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| 2. |
- Berndtsson, Ronny, et al.
(författare)
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Hydrology for Environmental Engineers
- 2014
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This textbook aims to provide a comprehensible introduction to Engineering Hydrology for environmental engineering students. The book comprises of 8 chapters which provide a holistic view of hydrology, seen as the water transport in nature with human influence, and deal with the main hydrological systems and processes. Each chapter ends with a few engineering examples together with a discussion of calculation methods, followed by further engineering problems. The book has been compiled from earlier hydrology textbooks from the Department of Water Resources Engineering at LTH, Lund University, Sweden. The most important contributions are from Lars Anderberg (“Kort introduktion till hydrologi”) and Rolf Larsson (“Övningsexempelsamling avsett för Väg&vatten-byggnadsingenjörer vid LTH”).
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| 3. |
- Berndtsson, Ronny, et al.
(författare)
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Riseberga Restoration Project
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This project is designed as a typical consultancy work for Environmental Engineering students at the Faculty of Engineering (LTH), Lund University, Sweden. It gives students a feeling of a possible future work by being a practical training in solving a complex environmental problem involving hydrological and ecological challenges. Additionally, the project work provides training of critical thinking, engineering techniques and presentation of technical reports. The outcome of this work is a proposal for restoration of a wetland at Riseberga River Basin in Malmö, southern Sweden. It will be presented as a report as well as an oral presentation of the restoration plan at the end of the semester by each group.
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| 4. |
- Blösch, Günter, et al.
(författare)
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Twenty-three unsolved problems in hydrology (UPH) - a community perspective
- 2019
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 64:10, s. 1141-1158
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Tidskriftsartikel (refereegranskat)abstract
- This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.
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| 5. |
- Davtalab, Rahman, et al.
(författare)
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Improving Continuous Hydrologic Modeling of Data-Poor River Basins Using Hydrologic Engineering Center's Hydrologic Modeling System : Case Study of Karkheh River Basin
- 2017
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Ingår i: Journal of hydrologic engineering. - 1084-0699 .- 1943-5584. ; 22:8
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Tidskriftsartikel (refereegranskat)abstract
- This paper applies HEC-HMS to the Karkheh River basin (KRB), Iran, and facilitates the calibration of a continuous hydrologic model (CHM) with soil moisture accounting (SMA) and snowmelt degree-day parameters. Manual calibration was performed to ensure the physical relevance of HEC-HMS parameter values. Because manual calibration entails changing each parameter value in a user-defined setting, it is often a time-consuming procedure complicated by multitude of interacting parameters. To address this setback, an event-based calibration technique (EBCT) was implemented in KRB and its interior sub-basins whereby the governing parameters of specific fall, spring, and winter events were initially estimated in a precalibration step and used as inputs to facilitate calibration of the CHM. Model performance analyzed based on goodness-of-fit criteria with respect to peak flows, low flows, and hydrograph shape reflects uncertainties associated with streamflow naturalization and use of average annual parameter values for the snowmelt component. Sensitivity analysis provided insights into the basin's snowfall and melt characteristics, distinguishing antecedent temperature index (ATI) cold rate coefficient and baseflow recession coefficient as key parameters affecting hydrograph shape and magnitude of the peak flow, respectively. Results based on goodness of fit metrics suggest that event-based parameter estimation using seasonal characteristics improved the efficiency and accuracy of the continuous HEC-HMS model (CORRL and NSE 0.78-0.87 and 0.5-0.7, respectively) while facilitating application to a large, data-poor river basin with heterogeneous climatic conditions.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Khatami, Sina, et al.
(författare)
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Benefits of GIS Application in Hydrological Modeling: A Brief Summary
- 2014
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 70:1, s. 41-49
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Forskningsöversikt (refereegranskat)abstract
- During recent years, Geographic Information Systems (GIS) as a powerful tool have had a tremendous impact on research techniques in the realm of geography and spatial analysis. The integrative ability of GIS to capture, store, manipulate, analyze, manage, and finally present all types of geographical spatial data, has drawn many attentions to it. Water Resources Engineering as a interdisciplinary field requires modeling and analyzing data with different spatial resolutions. Therefore, GIS could definitely be utilized as a suitable tool for solving water resources problems from local to global scale. This paper tries to present the larger scheme of the benefits for the applications of GIS in water resources and hydrological modeling in particular. Certainly, within the few pages ahead only the surface is scratched and a more thorough and comprehensive review requires more time and effort. The fundamental reason for the need of integrating GIS and hydrological modeling is briefly discussed and different tools are introduced. Also, various examples of GIS application are presented to create a better understanding. Case studies such as the Wadi Madoneh Basin in Jordan, Kuronagi River in Japan and San Antonio River Basin in Central Texas, USA, are presented. The good agreement between the results from a fairly simple GIS model and observations in cases such as Kuronagi River and Wadi Madoneh is indicating a promising future for GIS application in hydrological modeling. Finally, the benefits of GIS utilization in the field are discussed and summarized.
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| 10. |
- Khatami, Sina, et al.
(författare)
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Equifinality and Flux Mapping : A New Approach to Model Evaluation and Process Representation Under Uncertainty
- 2019
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 55:11, s. 8922-8941
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Tidskriftsartikel (refereegranskat)abstract
- Uncertainty analysis is an integral part of any scientific modeling, particularly within the domain of hydrological sciences given the various types and sources of uncertainty. At the center of uncertainty rests the concept of equifinality, that is, reaching a given endpoint (finality) through different pathways. The operational definition of equifinality in hydrological modeling is that various model structures and/or parameter sets (i.e., equal pathways) are equally capable of reproducing a similar (not necessarily identical) hydrological outcome (i.e., finality). Here we argue that there is more to model equifinality than model structures/parameters, that is, other model components can give rise to model equifinality and/or could be used to explore equifinality within model space. We identified six facets of model equifinality, namely, model structure, parameters, performance metrics, initial and boundary conditions, inputs, and internal fluxes. Focusing on model internal fluxes, we developed a methodology called flux mapping that has fundamental implications in understanding and evaluating model process representation within the paradigm of multiple working hypotheses. To illustrate this, we examine the equifinality of runoff fluxes of a conceptual rainfall-runoff model for a number of different Australian catchments. We demonstrate how flux maps can give new insights into the model behavior that cannot be captured by conventional model evaluation methods. We discuss the advantages of flux space, as a subspace of the model space not usually examined, over parameter space. We further discuss the utility of flux mapping in hypothesis generation and testing, extendable to any field of scientific modeling of open complex systems under uncertainty.
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| 11. |
- Khatami, Sina
(författare)
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Evidence of Low-dimensional Determinism in Short Time Series of Solute Transport
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Investigating the vadose zone, the physics behind the temporal and spatial instabilities of flow (in unsaturated media) is still of question. Although chaotic approaches have been widely employed for identifying different surface hydrology processes, such as rainfall, runoff, lake volume, etc., they were not applied for subsurface systems as much. On this ground, the present study attempts to investigate nonlinear determinism in solute transport processes in vadose zone. Previously, a few studies have investigated/examined solute transport processes from the view point of nonlinear chaos. However, this is the first study that is directly analyzing solute transport time series from field experiments. Also, it is analyzing short time series (68 data points) from a soil profile (62 measurement probes). For this purpose, Correlation Dimension Method is used as the most celebrated nonlinear chaotic technique in the hydrological studies. In general, the results of correlation dimension analysis provide the minimum number of ordinary differential equations needed to map a given dynamics. This study placed its main focus on the evolution of Correlation Exponent (CE) vs. Embedding Dimension (EM). The oscillation of correlation exponents between different values (2-4) which is referred to as Instable Saturation (IS) has been observed. Plausible explanations for this instability is discussed. The values of correlation dimensions for stable saturation are 2 and 3 among which CD=3 is the most frequent CD for SS is 3; for the rest of SS, CD is 2. In case of instable saturation, however, CD values are varying between 2 and 4 where IS-2, 3 is the most frequent one. Although the results are not as ‘accurate’ as other hydro-chaotic studies which dealt with longer time series, the consistent pattern and the order of magnitude in the results are in good agreement with previous findings. On a large scheme, the results encouragingly indicate a promising avenue from the presuppositional perspective of stochasticism towards nonlinear determinism for hydrological studies especially subsurface processes.
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| 12. |
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| 13. |
- Khatami, Sina, et al.
(författare)
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Integrated Watershed Management to Save the UNESCO Biosphere Reserve Lake Urmia, Iran
- 2012
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- Lake Urmia is a hypersaline lake in northwest Iran. Due to its unique aquatic ecosystem it has been designated as a Biosphere Reserve by UNESCO and a National Park under the 1971 Ramsar Convention. The biodiversity of the lake is determined by its salinity and Artemia urmiana is the dominant invertebrate and also the key element of the lake’s food chain. The lake is relatively shallow and satellite data indicate that the water level has plummeted during the last 17 years due to a dramatic decline in surface water inflow and consequent increase in salinity of the lake (from 166 g/L in 1995 to about 340 g/L in 2008). Thus, the entire lake’s ecology is threatened. The lake represents about 7% of the total surface water in Iran. About 20 permanent and periodic rivers together with other episodic streams are flowing into the lake. These rivers along with precipitation are the major sources of inflow and evaporation is the main outflow from this endorheic lake. In view of the above, the main objective of this paper was to review the state of art of knowledge for the threatened lake and to suggest possible solutions to improve the lake´s ecology. Hydrological and hydraulic data for the area are quite limited with short records. Many previous studies, using the same data records, have arrived at quite different management options to restore the lake´s ecology. The fundamental reason for the threatened lake´s ecology appears to be the lack of sustainable management. The paper evaluates different management options and their environmental impact. Through a multidisciplinary integrated approach, possible short-term and long-term solutions are presented to manage the lake´s ecology and reach a sustainable watershed management through a lake restoration project. Suggested integrated watershed management includes consideration of population growth and water demand, cloud seeding and rainwater harvesting, freshwater inflow to the lake and improved irrigation methods, efficient salt industry, establishing a waste water treatment plant and developing tourism industry as a source of income. Further hydrological modeling studies are needed to study the combined effect of climate change and dam construction. The paper is closed by discussing practical implications of the study and scaling-up possibilities.
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| 14. |
- Khatami, Sina
(författare)
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Lake Urmia is disappearing
- 2015
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Ingår i: Etemad Daily Newspaper, No. 3166. ; , s. 17-17
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The present article is a translation—to Farsi—of an article by Dr. Ali Mirchi (postdoctoral research associate at the Department of Civil and Environmental Engineering, Michigan Technological University), Dr. Kaveh Madani (lecturer in Environmental Management at the Centre for Environmental Policy, Imperial College London) and Dr. Amir Aghakouchak (assistant professor at the Department of Civil and Environmental Engineering, University of California, Irvine), entitled "Lake Urmia: how Iran’s most famous lake is disappearing", published in The Guardian 23 January 2015. The article discusses how Lake Urmia, once the largest salt-water lake in the Middle East and twice as large as Luxembourg, is now disappearing. This study is conducted by an independent group of 10 concerned Iranian researchers at universities and research centers in US, UK and Canada. Due to the unavailability of reliable and consistent ground-truth data, they used NASA's high-resolution satellite observations to estimate the physiographic changes of the lake over the past four decades. The results show that the lake’s surface area, in September 2014, was about 12% of its average size in the 1970s. They discuss how and why Lake Urmia’s desiccation requires active involvement of local, national and international organisations and urge action.
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| 15. |
- Khatami, Sina, et al.
(författare)
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Suggesting a new diagram and convention for characterising and reporting model performance
- 2022
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Ingår i: EGU General Assembly 2022. - : European Geosciences Union (EGU).
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Konferensbidrag (refereegranskat)abstract
- A long-standing research issue, in the hydrological sciences and beyond, is that of developing methods to evaluate the predictive/forecasting skill, errors and uncertainties of a model (or model ensembles). Various methods have been proposed for characterising time series residuals, i.e. the differences between observed (or target) and modelled (or estimate) time series. Most notably, the Taylor Diagram summarises model performance via a single plot based on three related metrics: the (linear Pearson) correlation, standard deviation, and root mean squared differences of one or multiple pairs of target and estimate time series. Despite its theoretical elegance and widespread use, the Taylor diagram does not account for bias errors, which is an important summary statistic for evaluating model performance. Further, it is very common to evaluate, compare, and report on model “skill” by use of a single aggregate metric value, even when a vector of metrics is used to calibrate/train the model; most commonly this is a dimensionless efficiency metric such as Nash-Sutcliffe Efficiency (NSE) or Kling-Gupta Efficiency (KGE). Such “efficiency” metrics typically aggregate over multiple types of residual behaviours: for example the most commonly used version of KGE is based on correlation, bias, and variability errors, although the authors recommended that it should be applied in a context-dependent fashion based on which model behaviours are deemed to be important to a given situation. Nevertheless, the use of a single summary value fails to account for the interactions among the error component terms, which can be quite informative for the evaluation and benchmarking of models. In this study, we propose a new diagram that is as easy to use and interpret as the Taylor Diagram, while also accounting for bias. We further suggest a new convention for reporting model skill that is based on foundational error terms. Our vision is that this new diagram and convention will enable researchers and practitioners to better interpret and report model performance. We provide multiple numerical examples to illustrate how this approach can be used for evaluating performance in the context of multi-model and multi-catchment (large-sample) studies.
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| 16. |
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| 17. |
- Khatami, Sina, et al.
(författare)
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Urmia Lake Watershed Restoration in Iran: Short- and Long-Term Perspectives
- 2013
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- Urmia Lake (also known as Oroumieh Lake) is a shallow terminal lake located in northwest Iran and one of the largest permanent lakes in the Middle East. Due to its biodiversity it has been designated as a Biosphere Reserve by UNESCO and a National Park under the 1971 Ramsar Convention. At present, the entire lake’s watershed is threatened due to drought and abrupt decline of the lake’s water level and the consequent increase of salinity. The rapidly declining eco-environmental conditions have serious impacts on the socio-economy of the whole region. In this paper we review the environmental state of art and suggest measures to improve the lake’s ecology by short- and long-term restoration possibilities. There are indications that the hydrology of the area could be described by a chaotic climate and a low-dimensional dynamical system. However, also the human impact is strong due to mismanagement of water resources. It is concluded that a multidisciplinary integrated approach is needed to tackle the current critical situation.
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| 18. |
- Khatami, Sina, et al.
(författare)
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What is drought? The scientific understanding of drought: the primary step towards resolving Iran's water crisis
- 2015
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Ingår i: Etemad Daily Newspaper, No. 3193. ; , s. 7-7
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Abstract in Uncoded languagesIn this article we discuss four basic approaches to characterising droughts namely meteorological, hydrological, agricultural, and socioeconomic. In the first three approaches, drought is defined and measured as a physical phenomenon primarily related to the precipitation shortfall. Socioeconomic drought, nonetheless, is described and determined as the 'supply' and 'demand' in terms of water shortage in different socioeconomic systems. The specific case of Iran’s drought and water crisis is the main focus of this article, and is briefly compared to California’s ongoing drought. In cases such as Iran, the socioeconomic drought is a result of inefficient and unsustainable management of water resources. Therefore, we cannot simply associate droughts with climate variability and/or change. Furthermore, due to large uncertainties in climate modelling and water management scenarios, long-term prediction of drought is impossible.
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| 19. |
- Khazaei, Bahram, et al.
(författare)
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Climatic or regionally induced by humans? Tracing hydro-climatic and land-use changes to better understand the Lake Urmia tragedy
- 2019
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 569, s. 203-217
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Tidskriftsartikel (refereegranskat)abstract
- Lake Urmia-a shallow endemic hypersaline lake in northwest Iran-has undergone a dramatic decline in its water level (WL), by about 8 m, since 1995. The primary cause of the WL decline in Lake Urmia has been debated in the scientific literature, regarding whether it has been predominantly driven by atmospheric climate change or by human activities in the watershed landscape. Using available climate, hydrological, and vegetation data for the period 1981-2015, this study analyzes and aims to explain the lake desiccation based on other observed hydro-climatic and vegetation changes in the Lake Urmia watershed and classical exploratory statistical methods. The analysis accounts for the relationships between atmospheric climate change (precipitation P, temperature T), and hydrological (soil moisture SM, and WL) and vegetation cover (VC; including agricultural crops and other vegetation) changes in the landscape. Results show that P, T, and SM changes cannot explain the sharp decline in lake WL since 2000. Instead, the agricultural increase of VC in the watershed correlates well with the lake WL change, indicating this human-driven VC and associated irrigation expansion as the dominant human driver of the Lake Urmia desiccation. Specifically, the greater transpiration from the expanded and increasingly irrigated agricultural crops implies increased total evapotranspiration and associated consumptive use of water (inherently related to the irrigation and water diversion and storage developments in the watershed). Thereby the runoff from the watershed into the lake has decreased, and the remaining smaller inflow to the lake has been insufficient for keeping up the previous lake WL, causing the observed WL drop to current conditions.
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| 20. |
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| 21. |
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| 22. |
- Moallemi, E. A., et al.
(författare)
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Evaluating Participatory Modeling Methods for Co-creating Pathways to Sustainability
- 2021
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Ingår i: Earth's Future. - 2328-4277. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- The achievement of global sustainability agendas, such as the Sustainable Development Goals, relies on transformational change across society, economy, and environment that are co-created in a transdisciplinary exercise by all stakeholders. Within this context, environmental and societal change is increasingly understood and represented via participatory modeling for genuine engagement with multiple collaborators in the modeling process. Despite the diversity of participatory modeling methods to promote engagement and co-creation, it remains uncertain what the extent and modes of participation are in different contexts, and how to select the suitable methods to use in a given situation. Based on a review of available methods and specification of potential contextual requirements, we propose a unifying framework to guide how collaborators of different backgrounds can work together and evaluate the suitability of participatory modeling methods for co-creating sustainability pathways. The evaluation of method suitability promises the integration of concepts and approaches necessary to address the complexities of problems at hand while ensuring robust methodologies based on well-tested evidence and negotiated among participants. Using two illustrative case studies, we demonstrate how to explore and evaluate the choice of methods for participatory modeling in varying contexts. The insights gained can inform creative participatory approaches to pathway development through tailored combinations of methods that best serve the specific sustainability context of particular case studies.
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| 23. |
- Moallemi, E. A., et al.
(författare)
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Evaluating Participatory Modeling Methods for Co‐creating Pathways to Sustainability
- 2021
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Ingår i: Earth's Future. - : American Geophysical Union (AGU). - 2328-4277. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- The achievement of global sustainability agendas, such as the Sustainable Development Goals, relies on transformational change across society, economy, and environment that are co-created in a transdisciplinary exercise by all stakeholders. Within this context, environmental and societal change is increasingly understood and represented via participatory modeling for genuine engagement with multiple collaborators in the modeling process. Despite the diversity of participatory modeling methods to promote engagement and co-creation, it remains uncertain what the extent and modes of participation are in different contexts, and how to select the suitable methods to use in a given situation. Based on a review of available methods and specification of potential contextual requirements, we propose a unifying framework to guide how collaborators of different backgrounds can work together and evaluate the suitability of participatory modeling methods for co-creating sustainability pathways. The evaluation of method suitability promises the integration of concepts and approaches necessary to address the complexities of problems at hand while ensuring robust methodologies based on well-tested evidence and negotiated among participants. Using two illustrative case studies, we demonstrate how to explore and evaluate the choice of methods for participatory modeling in varying contexts. The insights gained can inform creative participatory approaches to pathway development through tailored combinations of methods that best serve the specific sustainability context of particular case studies.
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| 24. |
- Ollila, Hanna M., et al.
(författare)
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Narcolepsy risk loci outline role of T cell autoimmunity and infectious triggers in narcolepsy
- 2023
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Narcolepsy type 1 (NT1) is caused by a loss of hypocretin/orexin transmission. Risk factors include pandemic 2009 H1N1 influenza A infection and immunization with Pandemrix (R). Here, we dissect disease mechanisms and interactions with environmental triggers in a multi-ethnic sample of 6,073 cases and 84,856 controls. We fine-mapped GWAS signals within HLA (DQ0602, DQB1*03:01 and DPB1*04:02) and discovered seven novel associations (CD207, NAB1, IKZF4-ERBB3, CTSC, DENND1B, SIRPG, PRF1). Significant signals at TRA and DQB1*06:02 loci were found in 245 vaccination-related cases, who also shared polygenic risk. T cell receptor associations in NT1 modulated TRAJ*24, TRAJ*28 and TRBV*4-2 chain-usage. Partitioned heritability and immune cell enrichment analyses found genetic signals to be driven by dendritic and helper T cells. Lastly comorbidity analysis using data from FinnGen, suggests shared effects between NT1 and other autoimmune diseases. NT1 genetic variants shape autoimmunity and response to environmental triggers, including influenza A infection and immunization with Pandemrix (R).
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| 25. |
- Papacharalampous, Georgia, et al.
(författare)
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Global-scale massive feature extraction from monthly hydroclimatic time series : Statistical characterizations, spatial patterns and hydrological similarity
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 767
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Tidskriftsartikel (refereegranskat)abstract
- Hydroclimatic time series analysis focuses on a few feature types (e.g., autocorrelations, trends, extremes), which describe a small portion of the entire information content of the observations. Aiming to exploit a larger part of the available information and, thus, to deliver more reliable results (e.g., in hydroclimatic time series dustering contexts), here we approach hydroclimatic time series analysis differently, i.e., by performing massive feature extraction. In this respect, we develop a big data framework for hydroclimatic variable behaviour characterization. This framework relies on approximately 60 diverse features and is completely automatic (in the sense that it does not depend on the hydroclimatic process at hand). We apply the new framework to characterize mean monthly temperature, total monthly precipitation and mean monthly river flow. The applications are conducted at the global scale by exploiting 40-year-long time series originating from over 13 000 stations. We extract interpretable knowledge on seasonality, trends, autocorrelation, long-range dependence and entropy, and on feature types that are met less frequently. We further compare the examined hydroclimatic variable types in terms of this knowledge and, identify patterns related to the spatial variability of the features. For this latter purpose, we also propose and exploit a hydroclimatic time series dustering methodology. This new methodology is based on Breiman's random forests. The descriptive and exploratory insights gained by the global-scale applications prove the usefulness of the adopted feature compilation in hydroclimatic contexts. Moreover, the spatially coherent patterns characterizing the clusters delivered by the new methodology build confidence in its future exploitation. Given this spatial coherence and the scale-independent nature of the delivered feature values (which makes them particularly useful in forecasting and simulation contexts), we believe that this methodology could also be beneficial within regionalization frameworks. in which knowledge on hydrological similarity is exploited in technical and operative terms.
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