scholarly journals Assessing the impact of climate on annual and seasonal discharges at the Sremska Mitrovica station on the Sava River, Serbia

2021 ◽  
Author(s):  
Igor Leščešen ◽  
Mojca Šraj ◽  
Milana Pantelić ◽  
Dragan Dolinaj
Keyword(s):  
Distribution Functions ◽  
Negative Trend ◽  
Flood Frequency Analysis ◽  
Positive Trend ◽  
Discharge Data ◽  
Sava River ◽  
Increasing Trend ◽  
The Impact ◽  
Gauging Station ◽  
The Sava River

Abstract Flood frequency analysis was performed on annual maxima series for 90 years (1928–2017) of discharge data recorded at the Sremska Mitrovica gauging station on the Sava River. The three-parameter distributions (PearsonIII, Log-PearsonIII) are more suitable for modelling annual maxima than distribution functions with only two parameters (Normal, Log-normal, Gumbel). The Mann–Kendall test statistic indicated that there is no statistically significant trend identified in annual maximum discharges or average annual discharges. A positive increasing trend was observed in annual temperature, while annual precipitation shows a decreasing trend which is non-significant. The seasonality analysis found a statistically non-significant weak negative trend in discharge in spring, summer and autumn and a statistically non-significant weak positive trend in winter. During winter, spring, and summer a non-significant negative trend in precipitation was observed, while autumn has experienced a statistically significant increasing trend. Temperatures show a positive trend in all seasons, but only temperatures during the warm period show a statistically significant increase. The results demonstrate that decreasing discharges of the Sava River at the Sremska Mitrovica gauging station are mainly the consequence of decreasing precipitation and increasing temperature (increasing evaporation), which is consistent with the results of other studies of the region.

scholarly journals Long-term variability of solar irradiance and its implications for photovoltaic power in West Africa

2020 ◽  
Author(s):  
Ina Neher ◽  
Susanne Crewell ◽  
Stefanie Meilinger ◽  
Uwe Pfeifroth ◽  
Jörg Trentmann
Keyword(s):  
West Africa ◽  
Solar Irradiance ◽  
Dry Season ◽  
Negative Trend ◽  
Annual Data ◽  
Positive Trend ◽  
Data Set ◽  
Data Record ◽  
The Impact

<p><span><span>West Africa is one of the least developed regions in the world regarding the energy availability and energy security. Located close to the equator West Africa receives high amounts of global horizontal irradiance (GHI). Thus, solar power and especially photovoltaic (PV) systems seem to be a promising solution to provide electricity with low environmental impact. To plan and to dimension a PV power system climatological data for global horizontal irradiance (GHI) and its variability need to be taken into account. However, ground based measurements of irradiances are not available continuously and cover only a few discrete locations.</span></span></p><p><span><span>Data records of surface irradiance based on satellite measurements have the advantage of covering wide spatial regions and being available over long time periods. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Climate Monitoring (CM SAF) provides the Surface Solar Radiation Data Set-Heliosat, Edition 2.1 (SARAH-2.1), a 35 year long climate data record in an half hourly resolution, covering the whole of Africa and Europe.<br></span></span></p><p><span><span>In this study, the SARAH-2.1 data record (1983-2017) is used to analyze the impact of 35 years atmospheric variability and trend on GHI and PV yields over West Africa (defined as the region from 3°N to 20°N and 20°W to 16°E). The trend and the variability of solar irradiance is analyzed separately for the wet and dry season as well as for annual data. Furthermore, a simplified model provides high-resolution potential PV yields. </span></span></p><p><span><span>According to the SARAH-2.1 data record, solar irradiance is largest (with up to 300 W/m 2 daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W/m</span></span><sup><span><span>2</span></span></sup><span><span>/decade). Whereas, the solar irradiance is lower in southern West Africa with a negative trend (up to -5 W/m</span></span><sup><span><span>2</span></span></sup><span><span>/decade). The positive trend is mostly connected to the dry season, while the negative trend occurs during the wet season. PV yields show a strong meridional gradient with lowest values around 4 kWh/kWp in southern West Africa and reach more than 5 kWh/kWp in the Sahara and Sahel zone.</span></span></p><p><span><span>T</span></span><span><span>his poster will discuss the long-term trend and variability analysis of solar irradiance and highlight the implications for photovoltaic-based power systems in West Africa.</span></span></p>

Calibration of QUAL2E Model for the Sava River (Slovenia)

1999 ◽  
Vol 40 (10) ◽  
pp. 111-118 ◽  
Author(s):  
A. Drolc ◽  
J. Zagorc Končan
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Rate Constant ◽  
The United States ◽  
Low Flow ◽  
Flow Conditions ◽  
Sava River ◽  
The Impact ◽  
The Sava River ◽  
Oxygen Concentrations

The use of mathematical models is a good decision making tool in river basin management for selection of wastewater treatment technologies and for estimation of the impact of discharged wastewater on the quality of receiving streams. In rivers mostly polluted with degradable organic matter, the major effect of wastewater discharge results in a substantial decrease of dissolved oxygen. The model QUAL2E developed by the United States Environmental Protection Agency was applied to wastewater impact assessment in the Sava river (Slovenia). We present the procedures for the determination of input data for the QUAL2E model. The sediment oxygen demand rate constant was determined experimentally in situ using an specially designed device; the degradation rate constant was determined in a river laboratory model; hydrological characteristics were evaluated on the basis of empirical coefficients; while the reaeration rate constant was calculated on the basis of an energy dissipation model. The mathematical water quality model QUAL2E was calibrated on the basis of field and laboratory measurements and validated with an independent set of data for critical summer low flow conditions when the dissolved oxygen concentrations are low. A sensitivity analysis of the model was also performed. The validated model was then used to estimate the impact of municipal and industrial wastewater discharges on dissolved oxygen concentrations in the Sava river near Ljubljana. The model was used to simulate various conditions in the river and various degrees of treatment of discharged wastewaters. It is estimated according to the model predictions that at critical summer low flow conditions, wastewater should be treated to reach a BOD under 30 mg l−1 with the goal that Slovenian water quality standards are not violated, meaning a dissolved oxygen concentration above 5 mg l−1.

scholarly journals Frequency analysis of extreme floods in a highly developed river basin

2016 ◽  
Author(s):  
Tomohiro Tanaka ◽  
Yasuto Tachikawa ◽  
Yutaka Ichikawa ◽  
Kazuaki Yorozu
Keyword(s):  
River Basin ◽  
Frequency Analysis ◽  
River Discharge ◽  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Discharge Data ◽  
Extreme Floods ◽  
Extreme Flood ◽  
Flood Peaks ◽  
Gauging Station

Abstract. Design flood, river discharge with a particular return period, is fundamental to determine the scale of flood control facilities. In addition, considering a changing climate, not only frequencies of river discharge at design level but those of devastating flooding are also crucial. Characteristics of river discharge during extreme floods largely differ from those during others because of upstream dam operation and/or river overflow; however, flood frequency analysis (FFA) from past discharge data is difficult to represent such impact because river basins rarely experience floods over the design level after river improvement and dam construction. To account for the above impact on extreme flood frequencies, this study presented a rainfall-based flood frequency model (RFFM) that derives flood frequencies from probabilistic rainfall modelling that empirically represents probabilistic structure of rainfall intensity over a catchment by directly using observed spatial-temporal rainfall profiles. The RFFM was applied to the Yodo River basin, Japan and demonstrated that flood frequency estimations by the RFFM well represent past flood frequencies at the Hirakata gauging station. Furthermore, the RFFM showed that return periods of large flood peaks are estimated at extremely large values, reflecting decrease of discharge by the inundation in an upstream area of the gauging station. On the other hand, FFA from past discharge data did not represent this impact because it has not experienced such huge flood peaks in an observation period. This study demonstrated the importance of the RFFM for flood frequency estimations, including those exceeding the design level.

scholarly journals Synthesis of past isotope hydrology investigations in the area of Ljubljana, Slovenia

Geologija ◽  
2020 ◽  
Vol 63 (2) ◽  
pp. 251-270
Author(s):  
Klara Nagode ◽  
Tjaša Kanduč ◽  
Sonja Lojen ◽  
Branka Bračič Železnik ◽  
Brigita Jamnik ◽  
...  
Keyword(s):  
Surface Water ◽  
Stable Isotope ◽  
Large Scale ◽  
Numerical Data ◽  
Domestic Water ◽  
Sava River ◽  
The Impact ◽  
Ljubljansko Barje ◽  
The Sava River

Water isotope investigations are a powerful tool in water resources research as well as in understanding the impact that humans have on the water cycle. This paper reviews past hydrological investigations of the Ljubljansko polje and Ljubljansko barje aquifers that supply drinking water to the City of Ljubljana, with an emphasis on hydrogen, oxygen and carbon stable isotope ratios. Information about the methods used and results obtained are summarised, and the knowledge gaps identified. Overall, we identified 102 records published between 1976 and 2019. Among them, 41 reported stable isotope data of groundwater, surface water and precipitation and were further analysed. Isotope investigations of the Ljubljansko barje began in 1976, while groundwater and surface water investigations of the Ljubljansko polje and along the Sava River began as late as 1997. Isotope investigations of carbon started even later in 2003 in the Ljubljansko polje and in 2010 in the Ljubljansko barje. These investigations were performed predominantly in the frame of short-term groundwater research projects at five main wellfields and sites along the Sava River. Almost no large-scale, long-term stable isotope studies have been conducted. The exceptions include groundwater monitoring by the Union Brewery in Ljubljana (2003- 2014) and precipitation in Ljubljana since 1981. Since 2011, more detailed surveys of the Ljubljansko barje were performed, and in 2018, the first extensive investigation started at wellfields and objects that form part of the domestic water supply system. Given the number of available studies, we felt that publishing all the numerical data and appropriate metadata would allow for a better understanding of the short and long-term dynamics of water circulation in the urban environment. In the future, systematic long-term approaches, including the appropriate use of isotopic techniques, are needed.

Climatology and Trend of Tropical Cloud Cover Using Gridded Satellite (GridSat) Data

2021 ◽  
Author(s):  
Muhsin M
Keyword(s):  
Spatial Distribution ◽  
Cloud Cover ◽  
Indian Subcontinent ◽  
Negative Trend ◽  
Positive Trend ◽  
Equatorial Pacific Ocean ◽  
Low Level ◽  
A Value ◽  
Increasing Trend ◽  
The Tropics

Abstract Climatology and trend of different types of clouds over the tropics are studied using 22 year long (1998-2019) Gridded Satellite (GridSat) data. Brightness temperature in window and water vapor channel is used as the proxy for the cloud top altitude. Threshold and bispectral methods are used to classify clouds depending on their cloud top altitude. Clouds are classified into Low level clouds, Mid level clouds, Deep clouds, Very Deep clouds (VDC), and Semi Transparent Cirrus (STC) clouds. Climatology of the spatial distribution of each cloud type over the tropics is examined.Tropical mean of occurrence of different cloud types show a steady declining trend with a value of -0.18% /decade, -0.06% /decade, -2.12% /decade, -2.29% /decade for mid level clouds, deep clouds, STC, total clouds respectively. Low level cloud shows a steady increasing trend of 0.08% /decade. Interestingly, VDC shows a steady declining trend up to 2011, and thereafter it shows a significant increasing trend of 0.1% /decade. Though the spatial distribution of total cloud cover generally shows a negative trend, the Western equatorial Pacific Ocean, Indian subcontinent, Indian Ocean, and Saharan desert region show a positive trend. Though low level clouds show an increasing trend, the regions of abundant low clouds show a negative trend. VDC show a declining trend over the western Pacific region, whereas other prominent VDC regions show a positive trend.

BELGRADE GROUNDWATER SOURCE, CONDITION AND POSSIBLE DEVELOPMENT DIRECTIONS

2007 ◽  
Vol 2 (3) ◽  
Author(s):  
M. Dimkic ◽  
V. Tausanovic ◽  
M. Pusic ◽  
Đ Boreli-Zdravkovic ◽  
D. Đuric ◽  
...  
Keyword(s):  
Water Source ◽  
Extensive Study ◽  
River Bed ◽  
Sava River ◽  
Horizontal Drains ◽  
City Water ◽  
Groundwater Source ◽  
The Impact ◽  
The City ◽  
The Sava River

The Sava river alluvion was the only water-supplying resource in Belgrade for decades, until 1986 (Fig. 1). Since 1986, water-supplying resource has become the river Sava, from whose waterflow certain quantities of water are being tapped and treated. The water source consists of 100 wells with horizontal drains and certain number of vertical tubular wells. The basic water source problems are related to the yield decrease. The reasons are colmation of the river bed and well ageing. Recently, the impact of ageing and colmation of well drains is becoming more and more dominant. The problem of safe city water supply is becoming evident, because all the installations are placed on one resource – the Sava river. The problem of the city-water source interaction is also evident. The city is putting “pressure” on the source, and the protection zones of the source disturb the city. The realization of very extensive study is in progress, which should point to the directions and ways to solve these problems. This work shortly presents the Belgrade groundwater source. Also, it shortly presents the installation ageing at the Belgrade water source, and directions for solving the problem.

scholarly journals High-energy operator product expansion at sub-eikonal level

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Giovanni Antonio Chirilli
Keyword(s):  
Operator Product Expansion ◽  
Evolution Equations ◽  
Energy Operator ◽  
High Energy ◽  
Structure Functions ◽  
Distribution Functions ◽  
Impact Factors ◽  
Operator Product ◽  
The Impact ◽  
New Distribution

Abstract The high energy Operator Product Expansion for the product of two electromagnetic currents is extended to the sub-eikonal level in a rigorous way. I calculate the impact factors for polarized and unpolarized structure functions, define new distribution functions, and derive the evolution equations for unpolarized and polarized structure functions in the flavor singlet and non-singlet case.

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