Pub Date : 2018-12-01DOI: 10.15292/ACTA.HYDRO.2018.08
Anja Lešek, D. Žagar
We discuss modeling of the transport and decease of bacteria Escherichia coli in marine environments. We calculated the spatially variable decease coefficient of E. coli from the extrapolated measurement data on environmental parameters in accordance with Mancini's equation for bacteria stemming from the Rižana River and entering into the computational domain – the eastern part of the Koper Bay. Using pre-computed circulation data and the modified particle-tracking model Nafta3D we performed two-day simulations of an instantaneous and a continuous release from a single source. We analyzed locations of two particle types: free E. coli (ECF) and E. coli bound to suspended solids (ECA). We then analyzed the ECA and ECF activity decrease with a newly developed decease model, applying a first-order kinetics equation. In the given conditions a vast majority of ECA remained in the second basin of the Port of Koper and sank to the bottom layers. The decease time of 90% of the ECA (T90) was about 48 hours. The ECF remained closer to the surface; they moved more quickly and for the most part abandoned the second basin. The determined T90 was 6 and 10 hours in instantaneous and continuous release, respectively.
{"title":"Use of the particle tracking method for modelling the transport and deceasing of Escherichia coli in the sea","authors":"Anja Lešek, D. Žagar","doi":"10.15292/ACTA.HYDRO.2018.08","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.08","url":null,"abstract":"We discuss modeling of the transport and decease of bacteria Escherichia coli in marine environments. We calculated the spatially variable decease coefficient of E. coli from the extrapolated measurement data on environmental parameters in accordance with Mancini's equation for bacteria stemming from the Rižana River and entering into the computational domain – the eastern part of the Koper Bay. Using pre-computed circulation data and the modified particle-tracking model Nafta3D we performed two-day simulations of an instantaneous and a continuous release from a single source. We analyzed locations of two particle types: free E. coli (ECF) and E. coli bound to suspended solids (ECA). We then analyzed the ECA and ECF activity decrease with a newly developed decease model, applying a first-order kinetics equation. In the given conditions a vast majority of ECA remained in the second basin of the Port of Koper and sank to the bottom layers. The decease time of 90% of the ECA (T90) was about 48 hours. The ECF remained closer to the surface; they moved more quickly and for the most part abandoned the second basin. The determined T90 was 6 and 10 hours in instantaneous and continuous release, respectively.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47062311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-01DOI: 10.15292/acta.hydro.2018.10
A. Slavić, G. Kalčíková, A. J. Kokalj, A. Z. Gotvajn
The aim of this study was to evaluate the biodegradability of the artificial sweetener saccharin in surface waters and groundwater. Artificial sweeteners are generally persistent under environmental conditions and have been recently classified as emerging pollutants. Biodegradability in three surface waters and one groundwater was tested: the rivers Ljubljanica, Pivka, and Unica, and the groundwater Planina Cave (river Pivka). Under environmentally relevant conditions, saccharin degraded well in hypertrophic water (98%, 14 days) due to high concentrations of phosphorus and nitrogen. There was a longer lag phase and biodegradation time compared to the optimum conditions achieved in the standardized laboratory test. It has been concluded that saccharin is biodegradable in natural waters if said waters contain enough microorganisms and nutrients.
{"title":"Biodegradation of the artificial sweetener saccharin in surface waters and groundwaters","authors":"A. Slavić, G. Kalčíková, A. J. Kokalj, A. Z. Gotvajn","doi":"10.15292/acta.hydro.2018.10","DOIUrl":"https://doi.org/10.15292/acta.hydro.2018.10","url":null,"abstract":"The aim of this study was to evaluate the biodegradability of the artificial sweetener saccharin in surface waters and groundwater. Artificial sweeteners are generally persistent under environmental conditions and have been recently classified as emerging pollutants. Biodegradability in three surface waters and one groundwater was tested: the rivers Ljubljanica, Pivka, and Unica, and the groundwater Planina Cave (river Pivka). Under environmentally relevant conditions, saccharin degraded well in hypertrophic water (98%, 14 days) due to high concentrations of phosphorus and nitrogen. There was a longer lag phase and biodegradation time compared to the optimum conditions achieved in the standardized laboratory test. It has been concluded that saccharin is biodegradable in natural waters if said waters contain enough microorganisms and nutrients.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48285844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-01DOI: 10.15292/ACTA.HYDRO.2018.07
L. Globevnik, Maja Koprivšek, L. Snoj
With respect to the various European polices for water and environment protection, EU member states report to the European Commission through national monitoring programmes a wide variety of data on the pressures that aquatic ecosystems are facing. They further report data on the quality and quantity of water (“State of Environment”) at monitoring sites, and on the ecological and chemical status of surface waters under the Water Framework Directive. Many other databases on European waters (hydrographical databases as well as databases on state of water) were developed as a result of different European projects. There are also several sources about climatic data, data on river discharges, and data on pressures the water system is facing. All these databases are a welcome source of information, needed to analyse the pressures on and state of European inland waters, but they must be interlinked, harmonised, and entered into a common spatial database first. This was done within the MARS project, where we have interlinked and unified relevant available databases into a new spatial database. Data are now available in a new form to be used in analysis of state of inland aquatic ecosystems as a response to multiple pressures.
{"title":"Review of European Databases of Inland Waters Used in the MARS Spatial Database Development for the Purpose of Multiple Pressure Analysis","authors":"L. Globevnik, Maja Koprivšek, L. Snoj","doi":"10.15292/ACTA.HYDRO.2018.07","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.07","url":null,"abstract":"With respect to the various European polices for water and environment protection, EU member states report to the European Commission through national monitoring programmes a wide variety of data on the pressures that aquatic ecosystems are facing. They further report data on the quality and quantity of water (“State of Environment”) at monitoring sites, and on the ecological and chemical status of surface waters under the Water Framework Directive. Many other databases on European waters (hydrographical databases as well as databases on state of water) were developed as a result of different European projects. There are also several sources about climatic data, data on river discharges, and data on pressures the water system is facing. All these databases are a welcome source of information, needed to analyse the pressures on and state of European inland waters, but they must be interlinked, harmonised, and entered into a common spatial database first. This was done within the MARS project, where we have interlinked and unified relevant available databases into a new spatial database. Data are now available in a new form to be used in analysis of state of inland aquatic ecosystems as a response to multiple pressures.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41500793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-01DOI: 10.15292/acta.hydro.2018.09
T. Podobnikar
Environmental conditions and access to natural resources are important factors for human behaviour and choices about where to make settlements. This important information must be understood and abstracted into appropriate spatial datasets, so as to be modelled in geographic information systems (GIS). The main objective is to design and realize a seamless integrated digital elevation model (DEM) from several data sources, including bathymetry. The important focus of this paper is to collect and interpret the sea level data for the Central Dalmatian islands over the past 15,000 years, describing the entire case study’s implementation in terms of hydrology, landscape archaeology, geodesy, data quality assessment, and spatial analysis. The results demonstrate that the proposed model has the potential to rethink the archaeological theories of settlement patterns in the studied area. The limitation of the proposed study is a lower quality of bathymetric datasets, and the determination of the historical sea level due to a number of uncertain factors. The work has profound implications in terms of the developed GIS tools that make it possible to generate reliable datasets and simulate various scenarios, as well as for a non-destructive prediction of the past archaeological landscapes. The solution may help increase awareness about cultural heritage, environmental conservation, and climate change.
{"title":"Palaeotopography concerning sea level changes to rethink past human activities in central Dalmatian islands area, Adriatic Sea","authors":"T. Podobnikar","doi":"10.15292/acta.hydro.2018.09","DOIUrl":"https://doi.org/10.15292/acta.hydro.2018.09","url":null,"abstract":"Environmental conditions and access to natural resources are important factors for human behaviour and choices about where to make settlements. This important information must be understood and abstracted into appropriate spatial datasets, so as to be modelled in geographic information systems (GIS). The main objective is to design and realize a seamless integrated digital elevation model (DEM) from several data sources, including bathymetry. The important focus of this paper is to collect and interpret the sea level data for the Central Dalmatian islands over the past 15,000 years, describing the entire case study’s implementation in terms of hydrology, landscape archaeology, geodesy, data quality assessment, and spatial analysis. The results demonstrate that the proposed model has the potential to rethink the archaeological theories of settlement patterns in the studied area. The limitation of the proposed study is a lower quality of bathymetric datasets, and the determination of the historical sea level due to a number of uncertain factors. The work has profound implications in terms of the developed GIS tools that make it possible to generate reliable datasets and simulate various scenarios, as well as for a non-destructive prediction of the past archaeological landscapes. The solution may help increase awareness about cultural heritage, environmental conservation, and climate change.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47113455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-26DOI: 10.15292/ACTA.HYDRO.2018.06
C. Sezen, N. Bezak, M. Šraj
Modelling rainfall runoff is important for several human activities. For example, rainfall runoff models are needed for water resource planning and water system design. In this regard, the daily runoff was modelled using the Genie Rural, a 4-parameter Journalier (GR4J), Genie Rural, a 6-parameter Journalier (GR6J), and the CemaNeige GR6J lumped conceptual models that were developed by the IRSTEA Hydrology Group. The main difference among the tested models is in the complexity and processes that are considered in the various model versions. As a case study, the non-homogeneous mostly karst Ljubljanica River catchment down to the Moste discharge gauging station was selected. Models were evaluated using various efficiency criteria. For example, base flow index (BFI) was calculated for the results of all tested models and observed discharges in order to compare low flow simulation performance. Based on the presented results we can conclude that in case of the non-homogeneous and karst Ljubljanica catchment the CemaNeige GR6J yields better modelling results compared to the GR4J and GR6J models. Compared to the GR6J and GR4J model versions, the CemaNeige CR6J also includes the snow module and improved methodology for the low-flow simulations that are also included in the GR6J model version.
{"title":"Hydrological modelling of the karst Ljubljanica River catchment using lumped conceptual model","authors":"C. Sezen, N. Bezak, M. Šraj","doi":"10.15292/ACTA.HYDRO.2018.06","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.06","url":null,"abstract":"Modelling rainfall runoff is important for several human activities. For example, rainfall runoff models are needed for water resource planning and water system design. In this regard, the daily runoff was modelled using the Genie Rural, a 4-parameter Journalier (GR4J), Genie Rural, a 6-parameter Journalier (GR6J), and the CemaNeige GR6J lumped conceptual models that were developed by the IRSTEA Hydrology Group. The main difference among the tested models is in the complexity and processes that are considered in the various model versions. As a case study, the non-homogeneous mostly karst Ljubljanica River catchment down to the Moste discharge gauging station was selected. Models were evaluated using various efficiency criteria. For example, base flow index (BFI) was calculated for the results of all tested models and observed discharges in order to compare low flow simulation performance. Based on the presented results we can conclude that in case of the non-homogeneous and karst Ljubljanica catchment the CemaNeige GR6J yields better modelling results compared to the GR4J and GR6J models. Compared to the GR6J and GR4J model versions, the CemaNeige CR6J also includes the snow module and improved methodology for the low-flow simulations that are also included in the GR6J model version.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49408256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.15292/ACTA.HYDRO.2018.02
Sara Grobljar
The impact of flooding is significantly greater in urban areas than in rural environments, as the exposure and value of property and the likelihood of endangering human lives is higher. There is therefore a great need for hydraulic models, which can predict the direction and extent of flooding. Buildings pose obstacles to water flow, considerably affecting its course, wherefore buildings should be taken into account in hydraulic models. This study compared two different ways of taking account of buildings in mathematical hydraulic models. The first approach models buildings by increasing the value of the hydraulic roughness coefficient for building footprints, while the second approach includes buildings in a digital terrain model at their locations. We also analysed the sensitivity of modelling results in respect of the cell size of the computational mesh, which can significantly affect the results of hydraulic model. Hydraulic analysis was carried out with 2D model for area of Gornja Radgona, which would be the flood of the Mura River in the event a part of flood protection wall collapsed. The impact of cell size and the approach of modelling buildings on the run-off regime and flood hazard within the analysed area was checked by indicators, such as water depth, velocity of the water current, extent of flooded areas, spatial distribution of flood hazard classes, etc. Changes in the duration of flood propagation along the urban area were also analysed.
{"title":"Flood Modelling in Urban Areas","authors":"Sara Grobljar","doi":"10.15292/ACTA.HYDRO.2018.02","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.02","url":null,"abstract":"The impact of flooding is significantly greater in urban areas than in rural environments, as the exposure and value of property and the likelihood of endangering human lives is higher. There is therefore a great need for hydraulic models, which can predict the direction and extent of flooding. Buildings pose obstacles to water flow, considerably affecting its course, wherefore buildings should be taken into account in hydraulic models. This study compared two different ways of taking account of buildings in mathematical hydraulic models. The first approach models buildings by increasing the value of the hydraulic roughness coefficient for building footprints, while the second approach includes buildings in a digital terrain model at their locations. We also analysed the sensitivity of modelling results in respect of the cell size of the computational mesh, which can significantly affect the results of hydraulic model. Hydraulic analysis was carried out with 2D model for area of Gornja Radgona, which would be the flood of the Mura River in the event a part of flood protection wall collapsed. The impact of cell size and the approach of modelling buildings on the run-off regime and flood hazard within the analysed area was checked by indicators, such as water depth, velocity of the water current, extent of flooded areas, spatial distribution of flood hazard classes, etc. Changes in the duration of flood propagation along the urban area were also analysed.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41513401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.15292/ACTA.HYDRO.2018.03
Jure Zevnik, M. K. Fijavz, Daniel Kozelj
We present an efficient graph-theoretical method for partitioning water distribution networks (WDNs) into district metered areas (DMAs). The proposed algorithm consists of two main parts, namely WDN partitioning and DMA connection, and is tested on a real-life WDN, for which different weight cases are compared. The efficiency of the proposed DMA connection algorithm, in regard to the traditional combinatorics approach, is shown for various numbers of established DMAs. The final solution is selected according to the multi-criteria evaluation model, which was developed in order to reduce the subjective influence in the selection process and considers hydraulic, cost, and topological criteria. The results show that the newly proposed spectral partitioning method, namely generalized normalized cut, is appropriate for WDN partitioning and that we can further improve the quality of the obtained solutions by considering appropriate topological and cost-based WDN information in the partitioning process.
{"title":"Efficient Partitioning of Water Distribution Networks Using a Graph-Theoretical Approach","authors":"Jure Zevnik, M. K. Fijavz, Daniel Kozelj","doi":"10.15292/ACTA.HYDRO.2018.03","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.03","url":null,"abstract":"We present an efficient graph-theoretical method for partitioning water distribution networks (WDNs) into district metered areas (DMAs). The proposed algorithm consists of two main parts, namely WDN partitioning and DMA connection, and is tested on a real-life WDN, for which different weight cases are compared. The efficiency of the proposed DMA connection algorithm, in regard to the traditional combinatorics approach, is shown for various numbers of established DMAs. The final solution is selected according to the multi-criteria evaluation model, which was developed in order to reduce the subjective influence in the selection process and considers hydraulic, cost, and topological criteria. The results show that the newly proposed spectral partitioning method, namely generalized normalized cut, is appropriate for WDN partitioning and that we can further improve the quality of the obtained solutions by considering appropriate topological and cost-based WDN information in the partitioning process.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47423738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.15292/ACTA.HYDRO.2018.04
Vesna Vidmar, G. Petkovšek, D. Žagar
We simulated liquid sloshing in a circular road tanker during two typical manoeuvres, namely steady-turn and lane change. A quasi-static pendulum, a modified dynamic pendulum with adjustable rod length, and the SPH (Smooth Particle Hydrodynamics) model Tis Isat were applied to simulate liquid oscillations. A simplified vehicle-tanker overturning model was developed and applied in order to determine the overturning threshold for the first manoeuvre. The agreement of liquid oscillations between the applied methods was better in the second manoeuvre, while the maximum inclination of the liquid gravity centre was successfully simulated in both cases. Both dynamic methods, the SPH and the dynamic pendulum, show a significantly lower overturning threshold, while all methods show similar overturning behaviour for a vehicle with liquid cargo. The threshold computed using the SPH model is slightly higher than with the dynamic pendulum due to wall-particle and particle-particle interactions. The results and comparisons confirm the suitability of the SPH method for simulating sloshing in road tankers and also show the method’s advantages: realistic description of the non-linear free surface in real-time, along with a consideration of mixing and friction processes within the fluid.
{"title":"Simulation of fluid sloshing in a tank using the SPH and Pendulum methods","authors":"Vesna Vidmar, G. Petkovšek, D. Žagar","doi":"10.15292/ACTA.HYDRO.2018.04","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.04","url":null,"abstract":"We simulated liquid sloshing in a circular road tanker during two typical manoeuvres, namely steady-turn and lane change. A quasi-static pendulum, a modified dynamic pendulum with adjustable rod length, and the SPH (Smooth Particle Hydrodynamics) model Tis Isat were applied to simulate liquid oscillations. A simplified vehicle-tanker overturning model was developed and applied in order to determine the overturning threshold for the first manoeuvre. The agreement of liquid oscillations between the applied methods was better in the second manoeuvre, while the maximum inclination of the liquid gravity centre was successfully simulated in both cases. Both dynamic methods, the SPH and the dynamic pendulum, show a significantly lower overturning threshold, while all methods show similar overturning behaviour for a vehicle with liquid cargo. The threshold computed using the SPH model is slightly higher than with the dynamic pendulum due to wall-particle and particle-particle interactions. The results and comparisons confirm the suitability of the SPH method for simulating sloshing in road tankers and also show the method’s advantages: realistic description of the non-linear free surface in real-time, along with a consideration of mixing and friction processes within the fluid.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47222473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.15292/ACTA.HYDRO.2018.05
O. Bonacci, T. roje-Bonacci
The paper studies time series of characteristic (minimum, mean, and maximum) daily, monthly, and yearly air temperatures measured at the Zagreb Grič Observatory in the period from 1 Jan. 1881 to 31 Dec. 2017. The following five air temperatures indices (ATI) are analysed: (1) absolute minimum yearly, monthly, and daily; (2) mean yearly, monthly, and daily minimum; (3) average mean yearly, monthly, and daily; (4) mean yearly, monthly, and daily maximum; (5) absolute maximum yearly, monthly, and daily. Methods of Rescaled Adjusted Partial Sums (RAPS), regression and correlation analyses, F-tests, and t-tests are used in order to describe changes in air temperature regimes over 137 years. Using the RAPS method the five analysed yearly ATI time series durations of 137 years were divided into two sub-periods. The analyses made in this paper showed that warming of minimum air temperatures started in 1970, mean air temperatures in 1988, and maximum air temperatures in 1998. Results of t-tests show an extreme statistically significant jump in the average air-temperature values in the second (recent time) sub-periods. Results of the t-tests of monthly temperatures show statistically significant differences between practically all five pairs (except in two cases) of analysed monthly ATI subseries for the period from January to August. From September to December the differences for most of pairs (except in six cases) of the analysed monthly ATI subseries are not statistically significant. It can be concluded that the urban heat island influenced the increase in recent temperatures more strongly than global warming. It seems that urbanisation firstly and chiefly influenced the minimum temperatures, as well as that Zagreb’s urbanisation had a bigger impact on minimum temperatures than on maximums. Increasing trend in time series of maximum temperatures started 20 years later.
{"title":"Analyses of the Zagreb Grič observatory air temperatures indices for the period 1881 to 2017","authors":"O. Bonacci, T. roje-Bonacci","doi":"10.15292/ACTA.HYDRO.2018.05","DOIUrl":"https://doi.org/10.15292/ACTA.HYDRO.2018.05","url":null,"abstract":"The paper studies time series of characteristic (minimum, mean, and maximum) daily, monthly, and yearly air temperatures measured at the Zagreb Grič Observatory in the period from 1 Jan. 1881 to 31 Dec. 2017. The following five air temperatures indices (ATI) are analysed: (1) absolute minimum yearly, monthly, and daily; (2) mean yearly, monthly, and daily minimum; (3) average mean yearly, monthly, and daily; (4) mean yearly, monthly, and daily maximum; (5) absolute maximum yearly, monthly, and daily. Methods of Rescaled Adjusted Partial Sums (RAPS), regression and correlation analyses, F-tests, and t-tests are used in order to describe changes in air temperature regimes over 137 years. Using the RAPS method the five analysed yearly ATI time series durations of 137 years were divided into two sub-periods. The analyses made in this paper showed that warming of minimum air temperatures started in 1970, mean air temperatures in 1988, and maximum air temperatures in 1998. Results of t-tests show an extreme statistically significant jump in the average air-temperature values in the second (recent time) sub-periods. Results of the t-tests of monthly temperatures show statistically significant differences between practically all five pairs (except in two cases) of analysed monthly ATI subseries for the period from January to August. From September to December the differences for most of pairs (except in six cases) of the analysed monthly ATI subseries are not statistically significant. It can be concluded that the urban heat island influenced the increase in recent temperatures more strongly than global warming. It seems that urbanisation firstly and chiefly influenced the minimum temperatures, as well as that Zagreb’s urbanisation had a bigger impact on minimum temperatures than on maximums. Increasing trend in time series of maximum temperatures started 20 years later.","PeriodicalId":36671,"journal":{"name":"Acta Hydrotechnica","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41372528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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