| 1. |
- Bakhtar, Aydin, et al.
(författare)
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Spatio-Temporal Evaluation of GPM-IMERGV6.0 Final Run Precipitation Product in Capturing Extreme Precipitation Events across Iran
- 2022
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 14:10
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Tidskriftsartikel (refereegranskat)abstract
- Extreme precipitation events such as floods and droughts have occurred with higher frequency over the recent decades as a result of the climate change and anthropogenic activities. To understand and mitigate such events, it is crucial to investigate their spatio-temporal variations globally or regionally. Global precipitation products provide an alternative way to the in situ observations over such a region. In this study, we have evaluated the performance of the latest version of the Global Precipitation Measurement-Integrated Multi-satellitE Retrievals (GPM-IMERGV6.0 Final Run (GPM-IMERGF)). To this end, we have employed ten most common extreme precipitation indices, including maximum indices (Rx1day, Rx5day, CDD, and CWD), percentile indices (R95pTOT and R99pTOT), and absolute threshold indices (R10mm, R20mm, SDII, and PRCPTOT). Overall, the spatial distribution results for error metrics showed that the highest and lowest accuracy for GPM-IMERGF were reported for the absolute threshold indices and percentile indices, respectively. Considering the spatial distribution of the results, the highest accuracy of GPM-IMERGF in capturing extreme precipitations was observed over the western highlands, while the worst results were obtained along the Caspian Sea regions. Our analysis can significantly contribute to various hydro-metrological applications for the study region, including identifying drought and flood-prone areas and water resources planning.
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| 2. |
- Fernandez-Anez, Nieves, et al.
(författare)
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Current Wildland Fire Patterns and Challenges in Europe : A Synthesis of National Perspectives
- 2021
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Ingår i: Air, Soil and Water Research. - : SAGE Publications. - 1178-6221. ; 14, s. 1-19
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Forskningsöversikt (refereegranskat)abstract
- Changes in climate, land use, and land management impact the occurrence and severity of wildland fires in many parts of the world. This is particularly evident in Europe, where ongoing changes in land use have strongly modified fire patterns over the last decades. Although satellite data by the European Forest Fire Information System provide large-scale wildland fire statistics across European countries, there is still a crucial need to collect and summarize in-depth local analysis and understanding of the wildland fire condition and associated challenges across Europe. This article aims to provide a general overview of the current wildland fire patterns and challenges as perceived by national representatives, supplemented by national fire statistics (2009–2018) across Europe. For each of the 31 countries included, we present a perspective authored by scientists or practitioners from each respective country, representing a wide range of disciplines and cultural backgrounds. The authors were selected from members of the COST Action “Fire and the Earth System: Science & Society” funded by the European Commission with the aim to share knowledge and improve communication about wildland fire. Where relevant, a brief overview of key studies, particular wildland fire challenges a country is facing, and an overview of notable recent fire events are also presented. Key perceived challenges included (1) the lack of consistent and detailed records for wildland fire events, within and across countries, (2) an increase in wildland fires that pose a risk to properties and human life due to high population densities and sprawl into forested regions, and (3) the view that, irrespective of changes in management, climate change is likely to increase the frequency and impact of wildland fires in the coming decades. Addressing challenge (1) will not only be valuable in advancing national and pan-European wildland fire management strategies, but also in evaluating perceptions (2) and (3) against more robust quantitative evidence.
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| 3. |
- Ferreira, Carla S. S., et al.
(författare)
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Soil degradation in the European Mediterranean region : Processes, status and consequences
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 805
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Forskningsöversikt (refereegranskat)abstract
- Soil, a non-renewable resource, sustains life on Earth by supporting around 95% of global food production and providing ecosystem services such as biomass production, filtration of contaminants and transfer of mass and energy between spheres. Unsustainable management practices and climate change are threatening the natural capital of soils, particularly in the Mediterranean region, where increasing population, rapid land-use changes, associated socio-economic activities and climate change are imposing high pressures on the region's shallow soils. Despite evidence of high soil susceptibility to degradation and desertification, the true extent of soil degradation in the region is unknown. This paper reviews and summarises the scientific literature and relevant official reports, with the aim to advance this knowledge by synthesizing, mapping, and identifying gaps regarding the status, causes, and consequences of soil degradation processes in the European Mediterranean region. This is needed as scientific underpinning of efforts to counteract soil degradation in the region. Three main degradation categories are then considered: physical (soil sealing, compaction, erosion), chemical (soil organic matter, contamination, salinisation), and biological. We find some degradation processes to be relatively well documented (e.g. soil erosion), while others, such as loss of biodiversity, remain poorly addressed, with limited data availability. We suggest establishment of a continuous, harmonised soil monitoring system at national and regional scale in the Mediterranean region to provide comparable datasets and chart the spatial extent and temporal changes in soil degradation, and corresponding economic implications. This is critical to support decision making and fulfilment of related sustainable development goals.
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| 4. |
- Ghajarnia, Navid, et al.
(författare)
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Close co-variation between soil moisture and runoff emerging from multi-catchment data across Europe
- 2020
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Ingår i: Scientific Reports. - : Nature Research. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Soil moisture is an important variable for land-climate and hydrological interactions. To investigate emergent large-scale, long-term interactions between soil moisture and other key hydro-climatic variables (precipitation, actual evapotranspiration, runoff, temperature), we analyze monthly values and anomalies of these variables in 1378 hydrological catchments across Europe over the period 1980–2010. The study distinguishes results for the main European climate regions, and tests how sensitive or robust they are to the use of three alternative observational and re-analysis datasets. Robustly across the European climates and datasets, monthly soil moisture anomalies correlate well with runoff anomalies, and extreme soil moisture and runoff values also largely co-occur. For precipitation, evapotranspiration, and temperature, anomaly correlation and extreme value co-occurrence with soil moisture are overall lower than for runoff. The runoff results indicate a possible new approach to assessing variability and change of large-scale soil moisture conditions by use of long-term time series of monitored catchment-integrating stream discharges.
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| 5. |
- Ghajarnia, Navid, et al.
(författare)
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Data-Driven Worldwide Quantification of Large-Scale Hydroclimatic Covariation Patterns and Comparison With Reanalysis and Earth System Modeling
- 2021
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 57:10
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale covariations of freshwater fluxes and storages on land can critically regulate the balance of green (evapotranspiration) and blue (runoff) water fluxes, and related land-atmosphere interactions and hydroclimatic hazards. Such large-scale covariation patterns are not evident from smaller-scale hydrological studies that have been most common so far, and remain largely unknown for various regions and climates around the world. To contribute to bridging the large-scale knowledge gaps, we synthesize and decipher hydroclimatic data time series over the period 1980-2010 for 6,405 catchments around the world. From observation-based data, we identify dominant large-scale linear covariation patterns between monthly freshwater fluxes and soil moisture (SM) for different world parts and climates. These covariation patterns are also compared with those obtained from reanalysis products and Earth System Models (ESMs). The observation-based data sets robustly show the strongest large-scale hydrological relationship to be that between SM and runoff (R), consistently across the study catchments and their different climate characteristics. This predominantly strongest covariation between monthly SM and R is also the most misrepresented by ESMs and reanalysis products, followed by that between monthly precipitation and R. Comparison of observation-based and ESM results also shows that an ESM may perform well for individual monthly variables, but fail in representing the patterns of large-scale linear covariations between them. Observation-based quantification of these patterns, and ESM and reanalysis improvements for their representation are essential for fundamental understanding, and more accurate and reliable modeling and projection of large-scale hydrological conditions and changes under ongoing global and regional change.
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| 6. |
- Ghajarnia, Navid, et al.
(författare)
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Error Analysis on PERSIANN Precipitation Estimations : Case Study of Urmia Lake Basin, Iran
- 2018
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Ingår i: Journal of hydrologic engineering. - 1084-0699 .- 1943-5584. ; 23:6
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Tidskriftsartikel (refereegranskat)abstract
- In-depth evaluation and analysis of the error properties associated with satellite-based precipitation estimation algorithms can play an important role in the future development and improvements of these products. This study evaluates the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) daily data set from 2000 to 2011 in 69 pixels over a semiarid basin in northwest Iran and compares it with the data set of the existing rain-gauge network. Different analytical approaches and measures are used to examine PERSIANN performance seasonally and categorically. The residuals are also decomposed into true positive (hit), false negative (miss), and false alarm (FA) estimate biases in addition to systematic and random error components. The results show seasonal variability of PERSIANN precision in rainfall detection with substantial errors during winter and summer that are associated with high rates of FA ratio (more than 60%). The value of miss and FA biases (124 and -77,000mm, respectively, within the total data set) are considerably larger than hit and total bias (27 and 74,000mm, respectively) because these components contribute conversely and compensate each other by their opposite signs. Moreover, PERSIANN detects heavy rainfalls well with a probability of detection (POD) over 80%, but with serious biases. Generally, although the detection ability of PERSIANN improves as the rate of rainfall increases, its systematic error in simulation of the rainfall process also increases (from 5% systematic error to 90% in heavier rainfalls), leading to a low level of accuracy in the estimation of precipitation rate.
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| 7. |
- Ghajarnia, Navid, et al.
(författare)
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Evaluating the Evolution of ECMWF Precipitation Products Using Observational Data for Iran : From ERA40 to ERA5
- 2022
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Ingår i: Earth and Space Science. - : American Geophysical Union (AGU). - 2333-5084. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- European Center for Medium-Range Weather Forecasts Reanalysis (ERA), one of the most widely used precipitation products, has evolved from ERA-40 to ERA-20CM, ERA-20C, ERA-Interim, and ERA5. Studies evaluating the performance of individual ERA products cannot adequately assess the evolution of the products. We compared the performance of all ERA precipitation products at daily, monthly, and annual data (1980-2018) using more than 2100 Iran precipitation gauges. Results indicated that ERA-40 performed worst, followed by ERA-20CM, which showed only minor improvements over ERA-40. ERA-20C considerably outperformed its predecessors, benefiting from the assimilation of observational data. Although several previous studies have reported full superiority of ERA5 over ERA-Interim, our results revealed several shortcomings in ERA5 compared with the ERA-Interim estimates. Both ERA-Interim and ERA5 performed best overall, with ERA-Interim showing better statistical and categorical skill scores, and ERA5 performing better in estimating extreme precipitations. These results suggest that the accuracy of ERA precipitation products has improved from ERA-40 to ERA-Interim, but not consistently from ERA-Interim to ERA5. This study employed a grid-grid comparison approach by first creating a gridded reference data set through the spatial aggregation of point source observations, however, the results from a point-grid approach showed no change in the overall ranking of products (despite the slight changes in the error index values). These findings are useful for model development at a global scale and for hydrological applications in Iran.
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| 8. |
- Jaramillo, Fernando, et al.
(författare)
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Priorities and Interactions of Sustainable Development Goals (SDGs) with Focus on Wetlands
- 2019
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Ingår i: Water. - : MDPI. - 2073-4441. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Wetlands are often vital physical and social components of a country’s natural capital, as well as providers of ecosystem services to local and national communities. We performed a network analysis to prioritize Sustainable Development Goal (SDG) targets for sustainable development in iconic wetlands and wetlandscapes around the world. The analysis was based on the information and perceptions on 45 wetlandscapes worldwide by 49 wetland researchers of the Global Wetland Ecohydrological Network (GWEN). We identified three 2030 Agenda targets of high priority across the wetlandscapes needed to achieve sustainable development: Target 6.3—“Improve water quality”; 2.4—“Sustainable food production”; and 12.2—“Sustainable management of resources”. Moreover, we found specific feedback mechanisms and synergies between SDG targets in the context of wetlands. The most consistent reinforcing interactions were the influence of Target 12.2 on 8.4—“Efficient resource consumption”; and that of Target 6.3 on 12.2. The wetlandscapes could be differentiated in four bundles of distinctive priority SDG-targets: “Basic human needs”, “Sustainable tourism”, “Environmental impact in urban wetlands”, and “Improving and conserving environment”. In general, we find that the SDG groups, targets, and interactions stress that maintaining good water quality and a “wise use” of wetlandscapes are vital to attaining sustainable development within these sensitive ecosystems.
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| 9. |
- Kalantari, Zahra, et al.
(författare)
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Mapping of ecosystem services : Supply and demand for local climate regulation and nutrient regulation services
- 2022
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Ingår i: Urban Soil and Water Degradation. - : Elsevier BV. - 2468-9289. ; , s. 135-159
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Tidskriftsartikel (refereegranskat)abstract
- Global population growth and associated socio-economic development have led to rapid urban expansion worldwide, with management implications for sustainable natural resources and societal resilience. Natural ecosystems and the services they provide are essential for societal mitigation and adaptation to adverse environmental consequences in urban areas. Mapping ecosystem services is a valuable tool in spatial planning for urban development, as it provides a deeper understanding of complex human-natural system interactions. This study analyzed and mapped two ecosystem services (local climate regulation and nutrient regulation), which play a key role in mitigating the impacts of local and global climate change in urban areas and of nutrient loads entering surface waters. The specific cases analyzed (Amsterdam city and the Netherlands as a whole) provided insights into opportunity pathways for adaptive development and management of complex urban environments and can support policy and decision-making processes for a sustainable and resilient future.
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| 10. |
- Kåresdotter, Elisie, et al.
(författare)
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Distinguishing Direct Human-Driven Effects on the Global Terrestrial Water Cycle
- 2022
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Ingår i: Earth's Future. - : American Geophysical Union (AGU). - 2328-4277. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- Population growth is increasing the pressure on water resource availability. For useful assessment and planning for societal water availability impacts, it is imperative to disentangle the direct influences of human activities in the landscape from external climate-driven influences on water flows and their variation and change. In this study we used the water balance model, a gridded global hydrological model, to quantify and distinguish human-driven change components, modified by interventions such as dams, reservoirs, and water withdrawals for irrigation, industry, and households, from climate-driven change components on four key water balance variables in the terrestrial hydrological system (evapotranspiration, runoff, soil moisture, storage change). We also analyzed emergent effect patterns in and across different parts of the world, facilitating exploration of spatial variability and regional patterns on multiple spatial scales, from pixel to global, including previously uninvestigated parts of the world. Our results show that human activities drive changes in all hydrological variables, with different magnitudes and directions depending on geographical location. The differences between model scenarios with and without human activities were largest in regions with the highest population densities. In such regions, which also have relatively large numbers of dams for irrigation, water largely tends to be removed from storage and go to feed increased runoff and evapotranspiration fluxes. Our analysis considers a more complete set of hydrological variables than previous studies and can guide further research and management planning for future hydrological and water availability trends, including in relatively data-poor parts of the world.
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| 11. |
- Kåresdotter, Elisie, et al.
(författare)
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Mapping the Vulnerability of Arctic Wetlands to Global Warming
- 2021
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Ingår i: Earth's Future. - : American Geophysical Union (AGU). - 2328-4277. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Wetlands provide multiple ecosystem services of local and global importance, but currently there exists no comprehensive, high-quality wetland map for the Arctic region. Improved information about Arctic wetland extents and their vulnerability to climate change is essential for adaptation and mitigation efforts, including for indigenous people dependent on the ecosystem services that wetlands provide, as inadequate planning could result in dire consequences for societies and ecosystems alike. Synthesizing high-resolution wetland databases and datasets on soil wetness and soil types from multiple sources, we created the first high-resolution map with full coverage of Arctic wetlands. We assess the vulnerability of Arctic wetlands for the years 2050, 2075, and 2100, using datasets on permafrost extent, soil types, and projected mean annual air temperature from the HadGEM2-ES climate model for three change scenarios (RCP2.6, RCP4.5, and RCP8.5). Our mapping shows that wetlands cover approximately 3.5 million km(2) or roughly 25% of Arctic landmass and 99% of these wetlands are in permafrost areas, indicating considerable vulnerability to future climate change. Unless global warming is limited to scenario RCP2.6, robust results show that large areas of Arctic wetlands are vulnerable to ecosystem regime shifts. If scenario RCP8.5 becomes a reality, at least 50% of the Arctic wetland area would be highly vulnerable to regime shifts with considerable adverse impacts on human health, infrastructure, economics, ecosystems, and biodiversity. The developed wetland and vulnerability maps can aid planning and prioritization of the most vulnerable areas for protection and mitigation of change.
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| 12. |
- Moshir Panahi, Davood, et al.
(författare)
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Variability and change in the hydro-climate and water resources of Iran over a recent 30-year period
- 2020
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Ingår i: Scientific Reports. - : Nature Research. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive assessment of hydro-climatic variations and change trends is essential for understanding, mitigating, and adapting to key water resource changes in different parts of the world. We performed such an assessment on Iran, as representative of an arid/semi-arid and geopolitically important world region. We acquired and calculated data time series of surface temperature (T), precipitation (P), runoff (R), evapotranspiration (ET), and water storage change (DS), to determine their status and changes in and among the 30 main hydrological basins in Iran over the period 1986–2016. From 1986–2000 to 2001–2016, the country warmed, P mostly decreased and R even more so, while water storage was depleted (DS < 0) and ET increased in some basins. Overall, the extra water provided from primarily groundwater depletion has fed and kept ET at levels beyond those sustained by the annually renewable water input from P. This indicates unsustainable use of water for maintaining and expanding human activities, such as irrigated agriculture, in this part of the world.
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| 13. |
- Rahmati, Omid, et al.
(författare)
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Contribution of physical and anthropogenic factors to gully erosion initiation
- 2022
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Ingår i: Catena (Cremlingen. Print). - : Elsevier BV. - 0341-8162 .- 1872-6887. ; 210, s. 105925-105925
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Tidskriftsartikel (refereegranskat)abstract
- Losses of large volumes of soil through gully formation lead to serious environmental, societal, and economic problems for human societies. This study establishes a framework based on an artificial intelligence approach to investigate the impact of geo-environmental and topo-hydrological factors on gully occurrences in the Biram region, Iran. The maximum entropy, random forest, and boosted regression trees machine-learning models were applied. The relative importance of variables (RIV) was then determined and gully erosion susceptibility maps were generated. Model results were evaluated using cutoff–dependent and –independent metrics. All models identified road construction as the main cause of gully formation in the study region (RVI ranged between 27% and 34%), and a medium contribution of distance from stream (RVI = 15–18%), lithology (RVI = 12–15%) and land use (RVI = 8–12%). Other factors such as drainage density, topographic wetness index, aspect, slope, profile curvature, elevation and plan curvature showed lower relative importance (RIV < 10%). Planners should pay attention to minimizing gully erosion along roads, so that river systems and downstream communities are adequately protected.
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| 14. |
- Sjöberg, Ylva, 1982-, et al.
(författare)
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Scaling relations reveal global and regional differences in morphometry of reservoirs and natural lakes
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 822
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Tidskriftsartikel (refereegranskat)abstract
- Water bodies provide essential ecosystem services linked to morphometric features that might differ between natural lakes and reservoirs. We use the HydroLAKES global dataset to quantitatively compare large (area > 1 km(2)) reservoirs and natural lakes in terms of scaling exponents between morphometric measures (volume, area, shore length). These exponents are further compared to those expected from geometrical assumptions and constraints. Lakes cover a larger range of volumes for the same range of surface areas than reservoirs, and have a larger volume-area scaling exponent. The volume-area scaling exponent for reservoirs (but not natural lakes) and the area-shore length exponent for all water bodies follow the predictions for self-affine surfaces. Land cover and terrain influence the scaling relations more for lakes than for reservoirs. These morphometric differences may be used to model the impact of reservoirs and lakes on hydrological processes and associated ecosystem services at regional to global scales.
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| 15. |
- Ziveh, Akbar Rahmati, et al.
(författare)
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Spatio-temporal performance evaluation of 14 global precipitation estimation products across river basins in southwest Iran
- 2022
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 2214-5818. ; 44, s. 101269-
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Tidskriftsartikel (refereegranskat)abstract
- Study region: Karkheh and Karun basins (29 degrees-35 degrees N, 46 degrees-52 degrees E) are two large river basins (area 51,000 and 67,000 km2, respectively) with complex topography in southwest Iran.Study focus: Access to spatio-temporally consistent precipitation data is a key requirement for hydrological studies, especially in data-scarce regions. This study evaluated 14 global precipi-tation products against gauge observations from 2003 to 2012 in Karun and Karkheh basins, southwest Iran. Different categorical and statistical indices at varying spatial and temporal res-olution, including Kling-Gupta Efficiency (KGE), bias, correlation coefficient, and variability ratio, were used to evaluate the products.New hydrological insights for the region: For daily time steps, TMPA-3B42V7.0, MERRA-2, and CMORPH-BLDV1.0 outperformed all other products, with KGE > 0.3. TMPA-3B42V7.0, MERRA-2, and PERSIANN-CDR were the best-performing products for monthly time steps, with KGE> 0.5. ERA5-Land showed the highest positive bias (bias>1.5) compared with in-situ observations, particularly for mountainous southeastern parts of Karun basin. Overall, bias-adjusted products obtained by merging ground-based observations in the estimations outperformed the unadjusted versions. The spatial distribution of statistical error metrics indicated that almost all products showed their greatest uncertainties for mountainous regions due to complex precipitation pro-cesses in these regions. These results can contribute significantly to hydrological and water re-sources planning measures in the study region, including early flood warning systems, drought monitoring, and optimization of dam operation.
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| 16. |
- Åhlen, Imenne, et al.
(författare)
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Hydro-climatic changes of wetlandscapes across the world
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Assessments of ecosystem service and function losses of wetlandscapes (i.e., wetlands and their hydrological catchments) suffer from knowledge gaps regarding impacts of ongoing hydro-climatic change. This study investigates hydro-climatic changes during 1976–2015 in 25 wetlandscapes distributed across the world’s tropical, arid, temperate and cold climate zones. Results show that the wetlandscapes were subject to precipitation (P) and temperature (T) changes consistent with mean changes over the world’s land area. However, arid and cold wetlandscapes experienced higher T increases than their respective climate zone. Also, average P decreased in arid and cold wetlandscapes, contrarily to P of arid and cold climate zones, suggesting that these wetlandscapes are located in regions of elevated climate pressures. For most wetlandscapes with available runoff (R) data, the decreases were larger in R than in P, which was attributed to aggravation of climate change impacts by enhanced evapotranspiration losses, e.g. caused by land-use changes.
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