Highly-resolved hydro-meteorological trends in Norway: impacts of observed climate change on snowmelt- and rainfall dominated streamflow in Western vs. Eastern Norway

2020 ◽  
Author(s):  
Klaus Vormoor ◽  
Amalie Skålevåg ◽  
Axel Bronstert
Keyword(s):  
Geographical Location ◽  
High Temporal Resolution ◽  
Relative Importance ◽  
Hydrological Response ◽  
Daily Streamflow ◽  
Relative Contribution ◽  
Regression Approach ◽  
Rapid Temperature ◽  
Eastern Norway ◽  
Streamflow Trends

<p>Mountainous and Nordic regions are experiencing more rapid temperature increases as compared to regions at lower altitudes and latitudes. This will impact the hydrology in these regions.  For Norway, there is increasing evidence for gradually increasing temperatures and recent changes in the amount, intensity, and frequency of precipitation as well as in the number of days with snow cover. The most pronounced differences regarding their hydro-meteorological regime can be found between Western and Eastern Norway (Vestlandet vs. Østlandet). Most catchments in these regions are characterized by mixed snowmelt/rainfall streamflow regimes with peak flows during spring (dominant in Østlandet) and autumn (dominant in Vestlandet). Changes in the hydro-meteorological drivers will have direct implications on the snow regime, and thus, also on streamflow via their direct effect on the relative importance of snowmelt vs. rainfall for streamflow generation.</p><p>In this study, we analyze daily-resolved streamflow trends for 112 catchments in Western vs. Eastern Norway for the period 1983-2012 and compare them with daily-resolved trends in the hydro-meteorological drivers. We also estimate the relative contribution of snowmelt and rainfall on daily streamflow for each catchment and identify trends therein. This process-orientated approach at high temporal resolution allows for a better identification of (in)consistencies with changes in the hydro-meteorological drivers than simple seasonal comparisons. Lastly, we aim to attribute observed changes in daily streamflow to the most dominant hydro-meteorological drivers by applying seasonal multiple-regressions. The major findings of this study are as follows:</p><ul><li>The high-resolution trend analysis allows for in-depth seasonal-specific insights into the hydrological response of catchments with different hydrological regimes to changes in the hydro-meteorological drivers.</li> <li>Increasing (decreasing) contributions of rainfall (snowmelt) to streamflow generally agree with prior expectations. The trends, however, show differences in magnitude and timing, depending on the geographical location (Vestlandet vs. Østlandet) and altitude.</li> <li>The seasonal multiple regression approach suggests that daily streamflow changes can be explained best by adding temperature as an additional predictor to snowmelt and rainfall, which may indicate the changing relevance of evapotranspiration particularly during summer.</li> </ul>

scholarly journals Daily Streamflow Trends in Western vs. Eastern Norway and their Attribution to Hydro-Meteorological drivers

2021 ◽  
Author(s):  
Amalie Skålevåg ◽  
K Vormoor
Keyword(s):  
Time Series ◽  
Seasonal Changes ◽  
Kendall Test ◽  
Regional Warming ◽  
Trend Analyses ◽  
Daily Streamflow ◽  
Relative Contribution ◽  
Precipitation Regimes ◽  
Spring Flow ◽  
Eastern Norway

Climate change in terms of regional warming and modifications in precipitation regimes has large impacts on streamflow in regions where both rainfall and snowmelt are important runoff generating processes like in Norway. Hydrological impacts of recent changes in climate are usually investigated by trend analyses applied on annual, seasonal, or monthly time series. However, neither of them can detect sub-seasonal changes and their underlying causes. Based on high-resolution trend analyses (i.e., applying the Mann-Kendall test on 10-day-moving-averaged daily time series), this study investigated sub-seasonal changes in daily streamflow, rainfall, and snowmelt in 61 and 51 catchments in Western vs. Eastern Norway (Vestlandet vs. Østlandet), respectively, over the period 1983-2012. The relative contribution of rainfall vs. snowmelt to daily streamflow and the changes therein have also been estimated to identify the changing relevance of these driving processes over the same period. Detected changes in daily streamflow were finally attributed to changes in the most important hydro-meteorological drivers using multiple-regression models with increasing complexity. Results reveal a coherent picture of earlier spring flow timing in both regions due to earlier snowmelt. Other streamflow trend patterns differ between both regions: Østlandet shows increased summer streamflow in catchments up to ~1100 m a.s.l. and slightly increased winter streamflow in about 50 % of the catchments, while trend patterns in Vestlandet are less coherent. The importance of rainfall for streamflow contribution has increased in both regions, and the trend attribution reveals that changes in rainfall and snowmelt can explain streamflow changes to some degree in periods and regions where they are dominant (snowmelt: spring and Østlandet; rainfall: autumn and Vestlandet). However, detected streamflow changes can be best explained by adding temperature as an additional predictor which indicates the relevance of additional driving processes for streamflow changes like increased glacier melt and evapotranspiration.

scholarly journals The Relative Importance of Scavenging, Oxidation, and Ice-Phase Processes in the Production and Wet Deposition of Sulfate

2005 ◽  
Vol 62 (7) ◽  
pp. 2118-2135 ◽  
Author(s):  
Vlado Spiridonov ◽  
Mladjen Curic
Keyword(s):  
Wet Deposition ◽  
Lower Percentage ◽  
Relative Importance ◽  
Total Sulfur ◽  
Sulfate Production ◽  
Relative Contribution ◽  
Cloud Resolving Model ◽  
Cloud Scavenging ◽  
Nucleation Scavenging ◽  
Ice Phase

Abstract The relative importance of various processes to sulfate production and wet deposition is examined by using a cloud-resolving model coupled with a sulfate chemistry submodel. Results using different versions of the model are then compared and principal differences with respect to their dynamics, microphysics, and chemistry are carefully discussed. The results imply that the dominant microphysical and chemical conversions of sulfate in the 3D run are nucleation, scavenging, and oxidation. Due to the lower cloud water and rainwater pH, oxidation does not contribute as significantly to the sulfate mass in the 2D run as the 3D. Sensitivity tests have revealed that in-cloud scavenging in the 2D run for continental nonpolluted and continental polluted clouds accounted for 29.4% and 31.5% of the total sulfur deposited, respectively. The 3D run shows a lower percentage contribution to sulfur deposition for about 28.2% and 29.6%. In addition, subcloud scavenging for the 2D run contributed about 32.7% and 38.2%. In-cloud oxidation in the 2D run accounted for about 24.5% to 30.4% of the total sulfur mass deposited. Subcloud oxidation contributed from 21.0% to 20.6% of the total sulfur mass removed by wet deposition. In-cloud oxidation for the 3D run shows slightly lower percentage values when compared to those from the 2D run. The relative contribution of subcloud oxidation for continental nonpolluted and polluted clouds exceeds those values in the 2D run by approximately 7% and 10%, respectively. Ignoring the ice phase and considering those types of convective clouds in the 2D run may lead to a higher value of the total sulfur mass removed by the wet deposition of about 33.9% to 39.2% for the continental nonpolluted and 36.2% to 45.6% for the continental polluted distributions relative to the base runs.

Demography of Xenosaurus platyceps (Squamata: Xenosauridae): a comparison between tropical and temperate populations

2008 ◽  
Vol 29 (2) ◽  
pp. 245-256 ◽  
Author(s):  
Carissa Jones ◽  
Isaac Rojas-González ◽  
Julio Lemos-Espinal ◽  
Jaime Zúñiga-Vega
Keyword(s):  
Life History ◽  
Population Growth ◽  
Adult Mortality ◽  
Life History Strategies ◽  
Relative Importance ◽  
Theoretical Frameworks ◽  
Population Growth Rates ◽  
Relative Contribution ◽  
Two Populations ◽  
Average Fitness

Abstract There appears to be variation in life-history strategies even between populations of the same species. For ectothermic organisms such as lizards, it has been predicted that demographic and life-history traits should differ consistently between temperate and tropical populations. This study compares the demographic strategies of a temperate and a tropical population of the lizard Xenosaurus platyceps. Population growth rates in both types of environments indicated populations in numerical equilibrium. Of the two populations, we found that the temperate population experiences lower adult mortality. The relative importance (estimated as the relative contribution to population growth rate) of permanence and of the adult/reproductive size classes is higher in the temperate population. In contrast, the relative importance for average fitness of fecundity and growth is higher in the tropical population. These results are consistent with the theoretical frameworks about life-historical differences among tropical and temperate lizard populations.

A Dynamic Structural Model of Education and Skills Requirements for Careers in Information Systems

2011 ◽  
pp. 1-26 ◽  
Author(s):  
Glenn R. Lowry ◽  
Rodney L. Turner ◽  
Julie Fisher
Keyword(s):  
Professional Development ◽  
Information Systems ◽  
Structural Model ◽  
Soft Skills ◽  
Working Environment ◽  
Relative Importance ◽  
Relative Contribution ◽  
Dynamic Structural Model ◽  
Is Professionals ◽  
Career Progress

This chapter presents a dynamic structural model of the relative contribution and importance of education and skills required of information systems (IS) professionals. Model development took into account the technical skills found in many tertiary IS programs, other business-oriented academic studies, and soft skills sought by employers in new graduates. The model also includes features of the working environment which influence the career progress of IS graduates. Acknowledging the importance of these four areas, the authors present a second-order structural model that links these areas and compares the application of this model to IS students and decision makers who employ graduates. The model fits the data for the two groups and exhibits some unexpected outcomes in the area of soft skills, with students attributing more importance to soft skills than IS managers. The model was employed to identify gender differences in perceptions of the relative contribution and importance of education and skills required of IS professionals. The model also includes features of the working environment which influence the career progress of IS graduates. The model was used to describe how attitudes and perceptions of IS professionals change across career stages as measured by age groupings. Changes in perceptions across four major age groupings show significant differences with respect to these factors according to age groups and by inference, career stage. The model allows, with some confidence, a quantitative interpretation of the relative importance of the respective variables from the perspectives of the student and employer stakeholder groups toward the education and professional development of IS professionals. The model also suggests the presence of contrasting, gender-based quantitative views of the relative importance of the respective variables to the education and professional development of IS professionals.

scholarly journals Attribution of high resolution streamflow trends in Western Austria – an approach based on climate and discharge station data

2015 ◽  
Vol 19 (3) ◽  
pp. 1225-1245 ◽  
Author(s):  
C. Kormann ◽  
T. Francke ◽  
M. Renner ◽  
A. Bronstert
Keyword(s):  
Freezing Point ◽  
Snow Accumulation ◽  
Lower Altitude ◽  
Study Region ◽  
Daily Streamflow ◽  
Streamflow Data ◽  
The One ◽  
Streamflow Trend ◽  
Streamflow Trends

Abstract. The results of streamflow trend studies are often characterized by mostly insignificant trends and inexplicable spatial patterns. In our study region, Western Austria, this applies especially for trends of annually averaged runoff. However, analysing the altitudinal aspect, we found that there is a trend gradient from higher-altitude to lower-altitude stations, i.e. a pattern of mostly positive annual trends at higher stations and negative ones at lower stations. At mid-altitudes, the trends are mostly insignificant. Here we hypothesize that the streamflow trends are caused by the following two main processes: on the one hand, melting glaciers produce excess runoff at higher-altitude watersheds. On the other hand, rising temperatures potentially alter hydrological conditions in terms of less snowfall, higher infiltration, enhanced evapotranspiration, etc., which in turn results in decreasing streamflow trends at lower-altitude watersheds. However, these patterns are masked at mid-altitudes because the resulting positive and negative trends balance each other. To support these hypotheses, we attempted to attribute the detected trends to specific causes. For this purpose, we analysed trends of filtered daily streamflow data, as the causes for these changes might be restricted to a smaller temporal scale than the annual one. This allowed for the explicit determination of the exact days of year (DOYs) when certain streamflow trends emerge, which were then linked with the corresponding DOYs of the trends and characteristic dates of other observed variables, e.g. the average DOY when temperature crosses the freezing point in spring. Based on these analyses, an empirical statistical model was derived that was able to simulate daily streamflow trends sufficiently well. Analyses of subdaily streamflow changes provided additional insights. Finally, the present study supports many modelling approaches in the literature which found out that the main drivers of alpine streamflow changes are increased glacial melt, earlier snowmelt and lower snow accumulation in wintertime.

Above-ground biomass estimation for a shrubby mistletoe in an Amazonian savanna

2019 ◽  
Vol 36 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Sarah Rosane M. C. Fadini ◽  
Reinaldo I. Barbosa ◽  
Rafael Rode ◽  
Viviane Corrêa ◽  
Rodrigo F. Fadini
Keyword(s):  
Life Form ◽  
Food Resource ◽  
Keystone Species ◽  
Host Size ◽  
Biomass Estimation ◽  
Relative Importance ◽  
Above Ground Biomass ◽  
Ground Biomass ◽  
Relative Contribution ◽  
Poor Predictor

AbstractMistletoes are considered keystone species on woodlands and savannas worldwide, providing a food resource for a diversified fauna, as well as a nutrient-enriched litter. Infections can be large (∼1–3 m) and, in some parts of the Amazonian savannas, parasitize up to 70% of hosts locally. Despite these facts, biomass of mistletoes is rarely investigated. Here we constructed allometric models to predict the biomass stock of the shrubby mistletoe Psittacanthus plagiophyllus in an Amazonian savanna. In addition, we determined whether host size could be used as a proxy for mistletoe biomass. Finally, we compared the biomass of mistletoes with that of trees, to evaluate their relative importance. We have shown that: (1) biomass of leaves (46.1% ± 13.5%) are as important as of stems (47.8% ± 13.5%), and relative contribution of stems increases as plant grows; (2) the model including width, breadth and vertical depth was the best (SE = 0.39, R2 = 0.9) for predicting individual mistletoe biomass; (3) mistletoe load and biomass per host had a positive, but weak (R2 = 0.11 and 0.09, respectively), relationship with host size, and thus such host information is a poor predictor of mistletoe biomass; and (4) in comparison with trees, mistletoes constituted less than 0.15% (0.5–22 kg ha−1) of the total above-ground biomass, suggesting that this life-form is irrelevant to the local biomass stock despite its unequivocal biological importance.

scholarly journals Nitrate retention and removal in Mediterranean streams bordered by contrasting land uses: a <sup>15</sup>N tracer study

2009 ◽  
Vol 6 (2) ◽  
pp. 181-196 ◽  
Author(s):  
D. von Schiller ◽  
E. Martí ◽  
J. L. Riera
Keyword(s):  
Agricultural Land ◽  
N Cycling ◽  
Urban Stream ◽  
Relative Importance ◽  
Transfer Velocity ◽  
Nitrate Retention ◽  
Relative Contribution ◽  
Uptake Length ◽  
Agricultural Stream ◽  
Forested Stream

Abstract. We used 15N-labelled nitrate (NO3−) additions to investigate pathways of nitrogen (N) cycling at the whole-reach scale in three stream reaches with adjacent forested, urban and agricultural land areas. Our aim was to explore among-stream differences in: (i) the magnitude and relative importance of NO3− retention (i.e. assimilatory uptake) and removal (i.e. denitrification), (ii) the relative contribution of the different primary uptake compartments to NO3− retention, and (iii) the regeneration, transformation and export pathways of the retained N. Streams varied strongly in NO3− concentration, which was highest in the agricultural stream and lowest in the forested stream. The agricultural stream also showed the lowest dissolved oxygen (DO) concentration and discharge. Standing stocks of primary uptake compartments were similar among streams and dominated by detritus compartments (i.e. fine and coarse benthic organic matter). Metabolism was net heterotrophic in all streams, although the degree of heterotrophy was highest in the agricultural stream. The NO3− uptake length was shortest in the agricultural stream, intermediate in the urban stream, and longest in the forested stream. Conversely, the NO3− mass-transfer velocity and the areal NO3− uptake rate were highest in the urban stream. Denitrification was not detectable in the forested stream, but accounted for 9% and 68% of total NO3− uptake in the urban and the agricultural stream, respectively. The relative contribution of detritus compartments to NO3− assimilatory uptake was greatest in the forested and lowest in the agricultural stream. In all streams, the retained N was rapidly regenerated back to the water column. Due to a strong coupling between regeneration and nitrification, most retained N was exported from the experimental reaches in the form of NO3−. This study provides evidence of fast in-stream N cycling, although the relative importance of N retention and removal varied considerably among streams. Results suggest that permanent NO3− removal via denitrification may be enhanced over temporary NO3− retention via assimilatory uptake in heterotrophic human-altered streams characterized by high NO3− and low DO concentrations.

scholarly journals Selection of criteria for multi-criteria decision making of reservoir flood control operation

2017 ◽  
Vol 19 (4) ◽  
pp. 558-571 ◽  
Author(s):  
Feilin Zhu ◽  
Ping-an Zhong ◽  
Yimeng Sun ◽  
Bin Xu
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Flood Control ◽  
Relative Importance ◽  
Contribution Ratio ◽  
Control Operation ◽  
Relative Contribution ◽  
Flood Control Operation ◽  
Reservoir Flood Control Operation ◽  
Selection Of

In reservoir flood control operation, selection of criteria is an important part of the multi-criteria decision making (MCDM) procedure. This paper proposes a method to select criteria for MCDM of reservoir flood control operation based on the back-propagation (BP) neural network. According to the concept of ideal and anti-ideal points, we propose a method to generate training samples of the BP neural network via stochastic simulation. The topological structure of a three-layer BP neural network used for criteria selection is established. The relative importance of criteria is derived via the learned connection weights of a trained BP neural network, and its calculation method is proposed. The sensitivity curve method is employed to conduct sensitivity analysis, and the relative contribution ratio is defined to quantify the relative sensitivity strength of each criterion. We present the principle and threshold value of criteria selection based on the comprehensive discrimination index defined by the combination of the relative importance and relative contribution ratio. The Pubugou reservoir is selected as the case study. The results show that the proposed method can provide an effective tool for decision makers to select criteria before MCDM modeling of reservoir flood control operation.

scholarly journals Attribution of high resolution streamflow trends in Western Austria – an approach based on climate and discharge station data

2014 ◽  
Vol 11 (6) ◽  
pp. 6881-6922 ◽  
Author(s):  
C. Kormann ◽  
T. Francke ◽  
M. Renner ◽  
A. Bronstert
Keyword(s):  
High Altitude ◽  
Freezing Point ◽  
Daily Basis ◽  
Positive Temperature ◽  
Study Region ◽  
Daily Streamflow ◽  
Temperature Trends ◽  
Low Altitude ◽  
The One ◽  
Streamflow Trends

Abstract. The results of streamflow trend studies are often characterised by mostly insignificant trends and inexplicable spatial patterns. In our study region, Western Austria, this applies especially for trends of annually averaged runoff. However, analysing the altitudinal aspect, we found that there is a trend gradient from high-altitude to low-altitude stations, i.e. a pattern of mostly positive annual trends at higher stations and negative ones at lower stations. At mid-altitudes, the trends are mostly insignificant. These trends were most probably caused by the following two main processes: on the one hand, melting glaciers produce excess runoff at high-altitude watersheds. On the other hand, rising temperatures potentially alter hydrological conditions in terms of less snowfall, higher infiltration, enhanced evapotranspiration etc., which in turn results in decreasing streamflow trends at low-altitude watersheds. However, these patterns are masked at mid-altitudes because the resulting positive and negative trends balance each other. To verify these theories, we attributed the detected trends to specific causes. For this purpose, we analysed the trends on a daily basis, as the causes for these changes might be restricted to a smaller temporal scale than the annual one. This allowed for the explicit determination of the exact days of year (DOY) when certain streamflow trends emerge, which were then linked with the corresponding DOYs of the trends and characteristic dates of other observed variables, e.g. the average DOY when temperature crosses the freezing point in spring. Based on these analyses, an empirical statistical model was derived that was able to simulate daily streamflow trends sufficiently well. Analyses of subdaily streamflow changes provided additional insights. Finally, it was confirmed that the main drivers of alpine streamflow changes are increased glacial melt and earlier snow melt. However, further research is needed to explicitly determine which processes related to positive temperature trends lead to the summertime streamflow decreases.

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