| 1. |
- Abou Rafee, Sameh A., et al.
(författare)
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Land Use and Cover Changes versus climate shift : Who is the main player in river discharge? A case study in the Upper Paraná River Basin
- 2022
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797. ; 309
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Tidskriftsartikel (refereegranskat)abstract
- Assessing the relative contribution of Land Use and Cover Changes (LUCC) and climate changes on runoff still represents a great challenge for water resources management. This issue is particularly critical for the Upper Paraná River Basin (UPRB), one of the most important basins in South America and responsible for most of the production of food, ethanol, and electricity generation in Brazil. In this paper, we used the Soil and Water Assessment Tool (SWAT) to quantitatively assess the relative contribution of both forcings. The simulation period included a time of great importance for climate studies, known as the 1970s global climate shift, and of great impact on river discharge within the UPRB. Three land use and cover scenarios were assigned to the 1961–1990 period of simulations, representing land use and cover during a pristine period (around the Year 1500), 1960, and 1985. Thirteen years of precipitation before and after the climate shift (considered to be the period 1974–1977) were analyzed and compared. Results showed a precipitation increase for the basin in general after the climate shift. The increase in rainfall reached up to 15% in many northern areas and more than 20% in the southern parts of the basin. By comparing all simulations, results indicate that both LUCC and precipitation increase due to the climate shift had a significant effect on the changes in annual discharge of the largest rivers of the UPRB. However, the results suggest that the impact of the precipitation increase on the discharge exceeded that of the LUCC. Between 1960 and 1985 the LUCC accounts for about 16% of the increase of the median annual discharge, whereas climate shift accounts for an increase of about 32%. These findings, suggesting a more relevant role for the climate, are consistent with two recent water crisis experienced by the country in the last decades, caused by prolonged below-normal rainfall throughout 2001/2002 and again in 2014/2015.
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| 2. |
- Freitas, Aline A., et al.
(författare)
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Drought Assessment in São Francisco River Basin, Brazil : Characterization through SPI and Associated Anomalous Climate Patterns
- 2022
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The São Francisco River Basin (SFRB) is one of the main watersheds in Brazil, standing out for generating energy and consumption, among other ecosystem services. Hence, it is important to identify hydrological drought events and the anomalous climate patterns associated with dry conditions. The Standard Precipitation Index (SPI) for 12 months was used to identify hydrological drought episodes over SFRB 1979 and 2020. For these episodes, the severity, duration, intensity, and peak were obtained, and SPI-1 was applied for the longest and most severe episode to identify months with wet and dry conditions within the rainy season (Nov–Mar). Anomalous atmospheric and oceanic patterns associated with this episode were also analyzed. The results revealed the longest and most severe hydrological drought episode over the basin occurred between 2012 and 2020. The episode over the Upper portion of the basin lasted 103 months. The results showed a deficit of monthly precipitation up to 250 mm in the southeast and northeast regions of the country during the anomalous dry months identified through SPI-1. The dry conditions observed during the rainy season of this episode were associated with an anomalous high-pressure system acting close to the coast of Southeast Brazil, hindering the formation of precipitating systems.
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| 3. |
- Sörensen, Johanna Lykke, et al.
(författare)
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Decision Support Indicators (DSIs) and their role in hydrological planning
- 2024
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Ingår i: Environmental Science and Policy. - 1462-9011. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- Decision Support Indicators (DSIs) are metrics designed to inform local and regional stakeholders about the characteristics of a predicted (or ongoing) event to facilitate decision-making. In this paper, the DSI concept was developed to clarify the different aims of different kinds of indicators by naming them, and a framework was developed to describe and support the usage of such DSIs. The framework includes three kinds of DSI: hydroclimatic DSIs which are easy to calculate but hard to understand by non-experts; impact-based DSIs which are often difficult to calculate but easy to understand by non-experts; and event-based DSIs, which compare a current or projected state to a locally well-known historical event, where hydroclimatic and impact-based DSIs are currently mainly used. Tables and figures were developed to support the DSI development in collaboration with stakeholders. To develop and test the framework, seven case studies, representing different hydrological pressures on three continents (South America, Asia, and Europe), were carried out. The case studies span several temporal and spatial scales (hours-decades; 70–6,000 km2) as well as hydrological pressures (pluvial and riverine floods, drought, and water scarcity), representing different climate zones. Based on stakeholder workshops, DSIs were developed for these cases, which are used as examples of the conceptual framework. The adaptability of the DSI framework to this wide range of cases shows that the framework and related concepts are useful in many contexts.
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| 4. |
- Adell, Anna, et al.
(författare)
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Spatial and temporal wave climate variability along the south coast of Sweden during 1959–2021
- 2023
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Ingår i: Regional Studies in Marine Science. - 2352-4855. ; 63
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Tidskriftsartikel (refereegranskat)abstract
- This study presents 62 years of hindcast wave climate data for the south coast of Sweden from 1959–2021. The 100-km-long coast consists mainly of sandy beaches and eroding bluffs interrupted by headlands and harbours alongshore, making it sensitive to variations in incoming wave direction. A SWAN wave model of the Baltic Sea, extending from the North Sea to the Åland Sea, was calibrated and validated against wave observations from 16 locations distributed within the model domain. Wave data collected from open databases were complemented with new wave buoy observations from two nearshore locations within the study area at 14 and 15 m depth. The simulated significant wave height showed good agreement with the local observations, with an average R2 of 0.83. The multi-decadal hindcast data was used to analyse spatial and temporal wave climate variability. The results show that the directional distribution of incoming waves varies along the coast, with a gradually increasing wave energy exposure from the west towards the east. The wave climate is most energetic from October to March, with the highest wave heights in November, December, and January. In general, waves from westerly directions dominate the annual wave energy, but within the hindcast time series, a few years had larger wave energy from easterly directions. The interannual variability of total wave energy and wave direction is correlated to the North Atlantic Oscillation (NAO) index. In the offshore, the total annual wave energy had a statistically significant positive correlation with the NAO DJFM station-based index, with a Spearman rank correlation coefficient of 0.51. In the nearshore, the correlation was even stronger. Future studies should investigate the possibility of using the NAO index as a proxy for the wave energy direction and its effect on coastal evolution.
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| 5. |
- Berndtsson, Ronny, et al.
(författare)
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Climate change and transboundary water management in the Tunisian Mellegue Catchment
- 2017
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; :4, s. 131-144
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Human activities and climate change affect hydrological and sedimentological characteristics within catchments. For arid and semiarid areas this induces direct negative economic and environmental consequences on society. In fact, stability in the rainfall regime and less siltation trapped in reservoirs mean more water for irrigation, water supply, and better flood control. This is especially important in the Tunisian semiarid region where water needs are close to potential water resources and siltation is reducing the reservoir capacity rapidly. Wadi Mellegue was chosen in order to study trends of water resources availability. Linear regression modelling and Mann-Kendall tests were performed for trend analysis. The study dealt with rainfall, discharge, and sediment patterns in the catchment area during a 44-year period. The results display a common decline in rainfall depth at different time scales. However, a positive trend related to discharge and siltation process was found. An increase in vulnerability to the new climate conditions is described. Consequently, water resources and agricultural landscape management for the Mellegue catchment should be revised in order to ensure a sustainable up- and downstream catchment development.
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| 6. |
- Canedo-Rosso, Claudia, et al.
(författare)
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Precipitation variability and its relation to climate anomalies in the Bolivian Altiplano
- 2019
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088.
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation variability over the Bolivian Altiplano is strongly affected by local climate and temporal variation of large-scale atmospheric flow. Precipitation is the main water source for drinking water and agricultural production. For this reason, a better understanding of precipitation variability and its relation with climate phenomena can provide important information for forecasting of droughts and floods, disaster risk reduction, and improvement of water management. We present results of an analysis of the austral summer precipitation variability at six locations in the Bolivian Altiplano and connections to climate variability. For this purpose, the variability of the summer precipitation was related to El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Antarctic Meridional Mode (AMM), and Atlantic Multidecadal Oscillation (AMO). A statistically significant correlation between climate indices and precipitation was found in various spectral frequencies and power. The variability of the summer precipitation was associated with the climate indices using a band-pass filter, representing the signal at a particular period of time. For the ENSO, band-pass filtering was applied for Niño3.4 and Niño3 at band ~2–7 years, for NAO band ~5–8 years, and for AMM band ~10–13 years. The variability of summer precipitation was related to all studied climate modes by negative relationships. The physical explanation for this is first the dry air transported from the Pacific Ocean to the Altiplano during El Niño events. Second, NAO and ENSO are dynamically linked through teleconnections. Third, the intertropical convergence zone (ITCZ) shifts are northwards during the warm phases of AMM. These physical mechanisms lead to a reduced austral summer precipitation associated with positive phases of the ENSO, NAO, and AMM. The results can be used to better forecast precipitation in the Bolivian Altiplano and provide support for the development of policies to improve climate resilience and risk management of water supply.
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| 7. |
- Costa, Denis Duda, et al.
(författare)
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Long-term relationships between climate oscillation and basin-scale hydrological variability during rainy season in eastern Northeast Brazil
- 2018
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 63:11, s. 1636-1652
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Tidskriftsartikel (refereegranskat)abstract
- The high variability in the hydrological regime of the Eastern Hydrological Region (EHR) of Northeast Brazil often results in floods and droughts, leading to serious socio-economic issues. Therefore, this work aimed to investigate connections between spatiotemporal hydrological variability of the EHR and large-scale climate phenomena. Multivariate statistical techniques were applied to relate climate indices with hydrological variables within two representative river basins in the EHR. The results indicated a multi-annual relationship between the state of the sea surface temperature of the Atlantic and Pacific oceans and anomalous hydrological variability in the basins. In addition, the northern Tropical Atlantic conditions were shown to play an important role in modulating the long-term variability of the hydrological response of the basins, whilst only extreme ENSO anomalies seemed to affect the rainy season. This knowledge is an important step towards long-term prediction of hydrological conditions and contributes to the improvement of water resources planning and management in the EHR.
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| 8. |
- du, Yiheng, et al.
(författare)
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Multi-Space Seasonal Precipitation Prediction Model Applied to the Source Region of the Yangtze River, China
- 2019
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Ingår i: Water. - 2073-4441. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- This paper developed a multi-space prediction model for seasonal precipitation using a high-resolution grid dataset (0.5° × 0.5°) together with climate indices. The model is based on principal component analyses (PCA) and artificial neural networks (ANN). Trend analyses show that mean annual and seasonal precipitation in the area is increasing depending on spatial location. For this reason, a multi-space model is especially suited for prediction purposes. The PCA-ANN model was examined using a 64-grid mesh over the source region of the Yangtze River (SRYR) and was compared to a traditional multiple regression model with a three-fold cross-validation method. Seasonal precipitation anomalies (1961–2015) were converted using PCA into principal components. Hierarchical lag relationships between principal components and each potential predictor were identified by Spearman rank correlation analyses. The performance was compared to observed precipitation and evaluated using mean absolute error, root mean squared error, and correlation coefficient. The proposed PCA-ANN model provides accurate seasonal precipitation prediction that is better than traditional regression techniques. The prediction results displayed good agreement with observations for all seasons with correlation coefficients in excess of 0.6 for all spatial locations.
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| 9. |
- Duda Costa, Denis, et al.
(författare)
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Understanding drought dynamics during dry season in Eastern Northeast Brazil
- 2016
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Ingår i: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Eastern Northeast Brazil (ENEB) generally experiences a high variability in precipitation in the dry season, with amplitudes that can overcome 500mm. The understanding of this variability can help in mitigating the socio-economic issues related to the planning and management of water resources this region, which is highly vulnerable to drought. This work aims to assess spatio-temporal variability of precipitation during the dry season and investigate the relationships between climate phenomena and drought events in the ENEB, using univariate (Spearman correlation) and multivariate statistical techniques, such as Principal Component Analysis, Cluster Analysis, and Maximum Covariance Analysis. The results indicate that the variability of precipitation in the dry season can be explained mainly (62%) by local physical conditions and climate conditions have a secondary contribution. Further analysis of the larger anomalous events suggests that the state of Atlantic and Pacific oceans can govern the occurrence of those events, and the conditions of Atlantic Ocean can be considered a potential modulator of anomalous phenomena of precipitation in ENEB.
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| 10. |
- Fernández, Carla Eloisa, et al.
(författare)
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Disentangling population strategies of two cladocerans adapted to different ultraviolet regimes
- 2018
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 8:4, s. 1995-2005
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Tidskriftsartikel (refereegranskat)abstract
- Zooplankton have evolved several mechanisms to deal with environmental threats, such as ultraviolet radiation (UVR), and in order to identify strategies inherent to organisms exposed to different UVR environments, we here examine life-history traits of two lineages of Daphnia pulex. The lineages differed in the UVR dose they had received at their place of origin from extremely high UVR stress at high-altitude Bolivian lakes to low UVR stress near the sea level in temperate Sweden. Nine life-history variables of each lineage were analyzed in laboratory experiments in the presence and the absence of sub-lethal doses of UVR (UV-A band), and we identified trade-offs among variables through structural equation modeling (SEM). The UVR treatment was detrimental to almost all life-history variables of both lineages; however, the Daphnia historically exposed to higher doses of UVR (HighUV) showed a higher overall fecundity than those historically exposed to lower doses of UVR (LowUV). The total offspring and ephippia production, as well as the number of clutches and number of offspring atfirst reproduction, was directly affected by UVR in both lineages. Main differences between lineages involved indirect effects that affected offspring production as the age at first reproduction. We here show that organisms within the same species have developed different strategies as responses to UVR, although no increased physiological tolerance or plasticity was shown by the HighUV lineage. In addition to known tolerance strategies to UVR, including avoidance, prevention, or repairing of damages, we here propose a population strategy that includes early reproduction and high fertility, which we show compensated for the fitness loss imposed by UVR stress.
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| 11. |
- Fernández, Carla E., et al.
(författare)
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Local adaptation to UV radiation in zooplankton : a behavioral and physiological approach
- 2020
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet radiation (UVR) is recognized as a driving force for phenotypic divergence. Here, we aim at assessing the ability of zooplankton to induce UVR tolerance and disentangle the relative importance of local adaptations behind the expression of such tolerance. Two populations of Daphnia pulex, derived from environments strongly differing in UVR conditions, were exposed to UVR for 70 d to induce production of photo-protective compounds and changes in behavioral responses. We expected greater tolerance to UVR in individuals from the high-UVR (H-U) environment as well as a refuge demand inversely related to the level of pigmentation. However, the complementarity between physiological and behavioral strategies was only observed on animals from the Low-UVR environment (L-U). L-U animals developed photo-protective compounds and decreased their refuge demand when re-exposed to UVR, that is, tolerated more UVR, compared to their control siblings. Conversely, UVR-exposed individuals from the H-U environment even having developed higher levels of photo-protective compounds increased their refuge demand staying deeper in the water column compared to the control animals, likely expressing an evolutionary memory to seek refuge in deeper waters irrespective of the UVR level. Stronger changes were observed in the H-U population compared to the L-U population; thus, our results suggest that although changes in tolerance after UVR exposure were evident for both populations, the strength of the inductions was more related to local adaptation independently of the rearing environment, showing that UVR tolerance is dependent on the evolutionary history of each population.
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| 12. |
- Fontenelle, Ana, et al.
(författare)
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Temporal Understanding of the Water–Energy Nexus : A Literature Review
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 15:8
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Forskningsöversikt (refereegranskat)abstract
- Guaranteeing reliable access to water and clean energy has been one of the most debated topics to promote sustainable development, which has made the Water–Energy Nexus (WEN) a relevant field of study. However, despite much development of the WEN, there are still many gaps to be addressed. One of these gaps is the understanding of temporal features. To address this, this study aimed to identify, categorize, and analyze the main temporal features applied in WEN studies based on a review of academic publications from 2010 to 2021. The results showed that most of the recent literature has focused on understanding the WEN from a quantitative perspective, often does not provide clear motivations for their choice of time, and lacks understanding of the role of historical processes. To improve the temporal understanding in WEN research, there is a need to include more methodological diversity, enhance the understanding of historical developments, and diversify the data use. The presented measures provide a chance to improve the evaluation of key issues, enhance the understanding of drivers of trade-offs between the water and energy sectors, and ground the discussion besides quantification. Moreover, these measures help the scientific community better communicate results to a broader audience. View Full-Text
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| 13. |
- Guégan, Marion, et al.
(författare)
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Climate warming effects on hydropower demand and pricing in California
- 2011
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Ingår i: World Environmental and Water Resources Congress 2011 : Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress - Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress. - Reston, VA : American Society of Civil Engineers. - 9780784411735 ; , s. 1298-1307
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Konferensbidrag (refereegranskat)abstract
- High-elevation hydropower units in California might be sensitive to climate warming since they have been designed to take advantage of snowmelt and have low built-in storage capacities. Snowmelt is expected to shift to earlier in the year and the system might not be able to store sufficient water for release in high-electricity-demanding periods. Previous studies have tried to explore the climate warming effects on California's high-elevation hydropower system by focusing on the supply side only (exploring the effects of hydrological changes on generation and revenues). This study extends the previous work by also considering climate warming effects on hydropower demand and pricing. A long-term price forecasting tool is developed using Artificial Neural Network (ANN) models. California's Energy-Based Hydropower Optimization Model (EBHOM) is then applied to estimate the adaptability of California's high-elevation hydropower system to climate warming considering simultaneous changes in supply, demand and pricing. The model is run for dry and wet warming scenarios, representing a range of hydrological changes under climate change.
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| 14. |
- Kazemzadeh, Majid, et al.
(författare)
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Detecting the Greatest Changes in Global Satellite-Based Precipitation Observations
- 2022
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Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 14:21
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, the analysis of abrupt and non-abrupt changes in precipitation has received much attention due to the importance of climate change-related issues (e.g., extreme climate events). In this study, we used a novel segmentation algorithm, DBEST (Detecting Breakpoints and Estimating Segments in Trend), to analyze the greatest changes in precipitation using a monthly pixel-based satellite precipitation dataset (TRMM 3B43) at three different scales: (i) global, (ii) continental, and (iii) climate zone, during the 1998–2019 period. We found significant breakpoints, 14.1%, both in the form of abrupt and non-abrupt changes, in the global scale precipitation at the 0.05 significance level. Most of the abrupt changes were observed near the Equator in the Pacific Ocean and Asian continent, relative to the rest of the globe. Most detected breakpoints occurred during the 1998–1999 and 2009–2011 periods on the global scale. The average precipitation change for the detected breakpoint was ±100 mm, with some regions reaching ±3000 mm. For instance, most portions of northern Africa and Asia experienced major changes of approximately +100 mm. In contrast, most of the South Pacific and South Atlantic Ocean experienced changes of −100 mm during the studied period. Our findings indicated that the larger areas of Africa (23.9%), Asia (22.9%), and Australia (15.4%) experienced significant precipitation breakpoints compared to North America (11.6%), South America (9.3%), Europe (8.3%), and Oceania (9.6%). Furthermore, we found that the majority of detected significant breakpoints occurred in the arid (31.6%) and polar (24.1%) climate zones, while the least significant breakpoints were found for snow-covered (11.5%), equatorial (7.5%), and warm temperate (7.7%) climate zones. Positive breakpoints’ temporal coverage in the arid (54.0%) and equatorial (51.9%) climates were more than those in other climates zones. Here, the findings indicated that large areas of Africa and Asia experienced significant changes in precipitation (−250 to +250 mm). Compared to the average state (trend during a specific period), the greatest changes in precipitation were more abrupt and unpredictable, which might impose a severe threat to the ecology, environment, and natural resources.
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| 15. |
- Kazemzadeh, Majid, et al.
(författare)
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Linear and nonlinear trend analyses in global satellite‐based precipitation, 1998‐2017
- 2021
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Ingår i: Earth's Future. - 2328-4277. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation varies spatiotemporally in amount, intensity, and frequency. Although, much research has been conducted on analyzing precipitation patterns and variation at the global scale, trend types have still not received much attention. This study developed a new polynomial‐based model for detecting non‐linear and linear trends in a satellite precipitation product (TRMM 3B43) for the 1998‐2017 period at a near‐global scale. We used an automated trend classification method that detects significant trends and classifies them into linear and non‐linear (cubic, quadratic, and concealed) trend types in satellite‐based precipitation at near‐global, continental, and climate zone scales. We found that 12.3% of pixel‐based precipitation time series across the globe have significant trend at 0.05 significance level (50% positive and 50% negative trends). In all continents except Asia, decreasing trends were found to cover larger areas than corresponding increasing trends. Regarding climate zone and precipitation trend change, our results indicate that a linear trend is dominant in the warm temperate (77.7%) and equatorial climates (80.4%) while the least linear change was detected in the polar climate (68.9%). The combined results of continental and climate zone scales indicate significant increasing trends in Asia and arid climate over the last 20 years. Furthermore, positive trends were found to be more significant at the continental scale, particularly, in Asia relative to the climate zone scale. Linear change in precipitation (80%) was the most dominant trend observed as opposed to non‐linear (quadratic (11%) and cubic (9%)) trend types at the global scale.
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| 16. |
- Lintunen, Karoliina, et al.
(författare)
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Changes in the discharge regime of Finnish rivers
- 2024
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Ingår i: Journal of Hydrology: Regional Studies. - 2214-5818. ; 53
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Tidskriftsartikel (refereegranskat)abstract
- Study region: Finland divided into three subregions, each representing different environmental conditions. Study focus: This study investigates long-term changes in unregulated river discharge. Trends in high- and low-flow event volumes, magnitudes, timings, and frequencies are analysed across 36 gauging stations in 19 watershed areas from 1911 to 2021. The average measurement period for discharge in the stations is 60 years, with over 765,000 daily records examined statistically. New hydrological insights for the region: High-flow events show advancing timings and decreasing magnitudes, notably in the coastal region and less so in the north. These events, occurring from 6 to 68 days earlier in 21 stations, now in the late winter and early spring, align with increasing spring low-flow volumes. On a monthly scale, a trend of rising volume magnitude is observed in late autumn, winter, and early spring, especially in Northern Finland's rivers. High flows during autumn and winter occur 30 to 60 days later in 8 stations. Changes in the monthly mean volumes were found in 30 stations, suggesting a redistribution of annual volumes across a broader time period, while the overall annual volumes have remained relatively unchanged. This underscores the complexity of hydrological patterns, emphasizing the need to consider total volumes and their temporal distribution in analyses. The findings enhance understanding of current changes and align with findings in the boreal-subarctic area.
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| 17. |
- Monte, Benício Emanoel Omena, et al.
(författare)
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Hydrological and hydraulic modelling applied to the mapping of flood-prone areas
- 2016
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Ingår i: Revista Brasileira de Recursos Hidricos. - : FapUNIFESP (SciELO). - 1414-381X .- 2318-0331. ; 21:1, s. 152-167
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Tidskriftsartikel (refereegranskat)abstract
- Overbank flooding caused by historically high flows, such as that in the Rio Mundaú watershed (lying between the states of Alagoas and Pernambuco) in 2010, has been the cause of widespread damage. The purpose of work described in this paper was to propose a mapping of areas liable to flooding in the township of Rio Largo (Alagoas) in the Rio Mundaú watershed by means of an “off-line” coupling of the hydrological/hydraulic models (MGB-IPH/ HEC-RAS), through consideration of extreme floods with different return periods for discharge. The hydrological model had a parameterization appropriate for extreme floods, using as input rainfall data with different return periods. Calibration and validation of the hydrological model were adequate in drainage areas larger than 1500 km2, but were less acceptable in headwater drainage areas where different geology and soil cover gave rise to surface runoff. The hydraulic model showed good agreement with point observations of flood levels in 2010 in both rural and urban areas along the water-course (R² = 0.99; RMSE = 1.41 m and CV (RMSE) = 0.04). In urban areas distant from the river, however, flood levels were over-estimated, indicating a need to use more detailed Digital Elevation Models. Flood events with return period greater than 50 years have the potential to cause great damage (floods exceeding 0.46 km2 in the urban area). The study showed that the use of coupled models was a viable approach for mapping areas liable to flooding, when it is not possible to analyse local flow frequencies in support of a hydraulic model.
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| 18. |
- Olsson, Jonas, et al.
(författare)
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An Analysis of (Sub-)Hourly Rainfall in Convection-Permitting Climate Simulations Over Southern Sweden From a User’s Perspective
- 2021
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Ingår i: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- To date, the assessment of hydrological climate change impacts, not least on pluvial flooding, has been severely limited by i) the insufficient spatial resolution of regional climate models (RCMs) as well as ii) the simplified description of key processes, e.g., convective rainfall generation. Therefore, expectations have been high on the recent generation of high-resolution convection-permitting regional climate models (CPRCMs), to reproduce the small-scale features of observed (extreme) rainfall that are driving small-scale hydrological hazards. Are they living up to these expectations? In this study, we zoom in on southern Sweden and investigate to which extent two climate models, a 3-km resolution CPRCM (HCLIM3) and a 12-km non-convection permitting RCM (HCLIM12), are able to reproduce the rainfall climate with focus on short-duration extremes. We use three types of evaluation–intensity-based, time-based and event-based–which have been designed to provide an added value to users of high-intensity rainfall information, as compared with the ways climate models are generally evaluated. In particular, in the event-based evaluation we explore the prospect of bringing climate model evaluation closer to the user by investigating whether the models are able to reproduce a well-known historical high-intensity rainfall event in the city of Malmö 2014. The results very clearly point at a substantially reduced bias in HCLIM3 as compared with HCLIM12, especially for short-duration extremes, as well as an overall better reproduction of the diurnal cycles. Furthermore, the HCLIM3 model proved able to generate events similar to the one in Malmö 2014. The results imply that CPRCMs offer a clear potential for increased confidence in future projections of small-scale hydrological climate change impacts, which is crucial for climate-proofing, e.g., our cities, as well as climate modeling in general.
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| 19. |
- Olsson, Jonas, et al.
(författare)
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Hydrological climate change impact assessment at small and large scales: Key messages from recent progress in Sweden
- 2016
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Ingår i: Climate. - : MDPI. - 2225-1154. ; 4:3
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Forskningsöversikt (refereegranskat)abstract
- Hydrological climate change impact assessment is generally performed by following a sequence of steps from global and regional climate modelling, through data tailoring (bias-adjustment and downscaling) and hydrological modelling, to analysis and impact assessment. This "climate-hydrology-assessment chain" has been developed with a primary focus on applicability to a medium-sized rural basin, which has been and still is the main type of domain investigated in this context. However, impact assessment is to an increasing degree being performed at scales smaller or larger than the medium-sized rural basin. Small-scale assessment includes e.g., impacts on solute transport and urban hydrology and large-scale assessment includes e.g., climate teleconnections and continental modelling. In both cases, additional complexity is introduced in the process and additional demands are placed on all components involved, i.e., climate and hydrology models, tailoring methods, assessment principles, and tools. In this paper we provide an overview of recent progress with respect to small- and large-scale hydrological climate change impact assessment. In addition, we wish to highlight some key issues that emerged as a consequence of the scale and that need further attention from now on. While we mainly use examples from work performed in Europe for illustration, the progress generally reflects the overall state of the art and the issues considered are of a generic character.
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| 20. |
- Rafee, Sameh A.Abou, et al.
(författare)
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Large-scale hydrological modelling of the Upper Paraná River Basin
- 2019
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- The Upper Paraná River Basin (UPRB) has undergone many rapid land use changes in recent decades, due to accelerating population growth. Thus, the prediction of water resources has crucial importance in improving planning and sustainable management. This paper presents a large-scale hydrological modelling of the UPRB, using the Soil andWater Assessment Tool (SWAT) model. The model was calibrated and validated for 78 outlets, over a 32-year simulation period between 1984 and 2015. The results and the comparison between observed and simulated values showed that after the calibration process, most of the outlets performed to a satisfactory level or better in all objective functions analyzed with 86%, 92%, 76%, 88%, and 74% for Percent bias, Coefficient of determination, Nash-Sutcliffe efficiency, Kling-Gupta efficiency, and the Ratio of Standard deviation of observations to root mean square error, respectively. The model output provided in this work could be used in further simulations, such as the evaluation of the impacts of land use change or climate change on river flows of the Upper Paraná Basin.
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| 21. |
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| 22. |
- Sivakumar, B, et al.
(författare)
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Is correlation dimension a reliable indicator of low-dimensional chaos in short hydrological time series?
- 2002
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Ingår i: Water Resources Research. - 0043-1397. ; 38:2
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Tidskriftsartikel (refereegranskat)abstract
- The reliability of the correlation dimension estimation in short hydrological time series is investigated using an inverse approach. According to this approach, first predictions are made using the phase-space reconstruction technique and the artificial neural networks. The correlation dimension is estimated next independently and is compared with the prediction results. A short hydrological series, monthly runoff series of 48 years (with a total of only 576 values) observed at the Coaracy Nunes/Araguari River watershed in northern Brazil, is studied. The correlation dimension results are in reasonably good agreement with the optimal embedding dimension obtained from the phase-space method and the optimal number of inputs from the neural networks. No underestimation of the correlation dimension is observed due to the small data size, rather there seems to be a slight overestimation due to the presence of noise in the data. The results indicate that the accuracy of the correlation dimension may not be judged on the basis of the length of the time series but on whether the time series is long enough to reasonably represent the dynamical changes in the system. Such an observation suggests that the correlation dimension could indeed be a reliable indicator of low-dimensional chaos even in short hydrological time series, which is certainly encouraging news for hydrologists who often have to deal with short time series.
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| 23. |
- Uvo, Cíntia B., et al.
(författare)
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Detecting long-term change in flood risk
- 2014
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Ingår i: Applied Uncertainty Analysis for Flood Risk Management. - : IMPERIAL COLLEGE PRESS. - 9781848162709 - 9781848162716 ; , s. 565-577
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Bokkapitel (refereegranskat)
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| 24. |
- Uvo, Cintia B., et al.
(författare)
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The spatio-temporal influence of atmospheric teleconnection patterns on hydrology in Sweden
- 2021
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Ingår i: Journal of Hydrology: Regional Studies. - : Elsevier BV. - 2214-5818. ; 34
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Tidskriftsartikel (refereegranskat)abstract
- Study region: Sixty-four river gauging stations distributed over Sweden. Study focus: To investigate the influence of climate teleconnection patterns (TP) on streamflow in Sweden. Streamflow data is regionalized and the average hydrographs of each homogeneous region is divided into hydrological seasons. Thereafter the impact of different TPs on the streamflow, per homogeneous region and per hydrological season is analyzed. New hydrological insights for the region: Five homogeneous regions are identified; three located in the north, where snow dominates the hydrological processes, and two located in the south, where rain dominates hydrological processes. The northern hydrographs are separated into three hydrological periods: low streamflow when snow is accumulated, high streamflow during the melting of the snowpack and a transition period in between. The southern hydrographs are characterized by streamflow above the yearly average during the winter and below during the summer. Hydrological periods in different homogeneous regions are influenced by diverse combinations of TPs. Arctic Oscillation, North Atlantic Oscillation and Scandinavian Pattern influence the streamflow in most of the regions during most hydrological periods. The further south and east the region is located, the more TPs influence the streamflow. The resulting streamflow variability is related to the interplay between different TPs both before and during each hydrological period. This interplay may enhance or decrease the individual influence of each TP on streamflow.
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