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In this research work, an analysis is conducted concerning the impact on rainfall-runoff simulations of utilizing rain gauge precipitation measurements against weather radar quantitative precipitation estimates. The study area is the Sarantapotamos river basin, a peri-urban basin located in the greater area of Athens, and measurements from a newly installed X-Band weather radar system, referred to as rainscanner, along with ground rain gauge stations were used. Rainscanner, in contrast to rain gauges, is able to provide with higher resolution surface precipitation datasets, but due to signal errors, uncertainty is involved, and thus proper calibration and evaluation of these estimates must be first performed. In this context, this research work evaluates the impact of adopting different precipitation datasets and interpolation methods for generating runoff, through the use of a lumped based rainfall-runoff model. Initially, the analysis focuses on the correlation between the rain gauge and the rainscanner estimations for each station, as well as for the calculated mean areal precipitation. The results of the rainfall-runoff simulations show that even though a different spatial and temporal variability of the rainfall field is calculated through the two datasets, in a lumped-based scheme, the most important factor that dictates the runoff generation is the amount of total precipitation.
Apollon Bournas; Evangelos Baltas. Comparative Analysis of Rain Gauge and Radar Precipitation Estimates towards Rainfall-Runoff Modelling in a Peri-Urban Basin in Attica, Greece. Hydrology 2021, 8, 29 .
AMA StyleApollon Bournas, Evangelos Baltas. Comparative Analysis of Rain Gauge and Radar Precipitation Estimates towards Rainfall-Runoff Modelling in a Peri-Urban Basin in Attica, Greece. Hydrology. 2021; 8 (1):29.
Chicago/Turabian StyleApollon Bournas; Evangelos Baltas. 2021. "Comparative Analysis of Rain Gauge and Radar Precipitation Estimates towards Rainfall-Runoff Modelling in a Peri-Urban Basin in Attica, Greece." Hydrology 8, no. 1: 29.
An integrated methodological framework for assessing different flood mitigation measures in urban catchments is presented. The framework comprises hydrologic, hydraulic and economic indices aiming at quantifying the effect of different alternatives regarding flood hazard mitigation. The alternatives evaluated include both conventional drainage solutions and low impact development measures. The conventional drainage solutions were: (i) off-line detention tanks; and (ii) sewer enlargement. The low impact development measures included: (i) green roofs (GR); and (ii) permeable surfaces (PS). Each solution was modeled using SWMM5 with respect to flood reduction effectiveness, and the results were compared to those of the existing condition (i.e., no flood mitigation measures). All the examined solutions were also compared based on their construction and operation and maintenance costs for a typical lifespan (i.e., 30 years). The results of the simulation revealed that both low impact development measures and conventional drainage solutions were highly effective even for storm events with low probability of occurrence. However, sewer enlargement was found to be the best alternative from an economic perspective. Nevertheless, peak at the sewer exit increased and time to peak remained unchanged; as a result, local flooding problems are resolved but downstream flooding problems may be introduced. If other criteria are considered, i.e., traffic obstruction, noise, construction easiness, co-benefits and downstream impacts, low impact development measures become more attractive compared to conventional drainage solutions.
Ioannis M. Kourtis; Vassilios A. Tsihrintzis; Evangelos Baltas. A robust approach for comparing conventional and sustainable flood mitigation measures in urban basins. Journal of Environmental Management 2020, 269, 110822 .
AMA StyleIoannis M. Kourtis, Vassilios A. Tsihrintzis, Evangelos Baltas. A robust approach for comparing conventional and sustainable flood mitigation measures in urban basins. Journal of Environmental Management. 2020; 269 ():110822.
Chicago/Turabian StyleIoannis M. Kourtis; Vassilios A. Tsihrintzis; Evangelos Baltas. 2020. "A robust approach for comparing conventional and sustainable flood mitigation measures in urban basins." Journal of Environmental Management 269, no. : 110822.
The current analysis attempts to quantify the interlinkages between the water, energy and food sectors of California covering the period 2002–2015. The results reveal that 25% (60,696 GWh) of the annual energy consumption is attributed to agriculture, while 75% (174,709 GWh) is used for water supply purposes. The agricultural sector consumes 77% (32,629 m3) of the irrigation water, and the energy sector is vulnerable to water availability fluctuations, because many hydroelectric facilities are connected to its grid. Considering the water scarcity and the uneven geographical distribution of water in the state, its central role in California’s water–energy–food (WEF) Nexus becomes apparent.
Georgia Manou; Georgios Bariamis; Evangelos Baltas. Investigation and Assessment of the Management of Natural Resources in the State of California Using the Conceptual Framework of Water–Energy–Food Nexus. Environmental Sciences Proceedings 2020, 2, 28 .
AMA StyleGeorgia Manou, Georgios Bariamis, Evangelos Baltas. Investigation and Assessment of the Management of Natural Resources in the State of California Using the Conceptual Framework of Water–Energy–Food Nexus. Environmental Sciences Proceedings. 2020; 2 (1):28.
Chicago/Turabian StyleGeorgia Manou; Georgios Bariamis; Evangelos Baltas. 2020. "Investigation and Assessment of the Management of Natural Resources in the State of California Using the Conceptual Framework of Water–Energy–Food Nexus." Environmental Sciences Proceedings 2, no. 1: 28.
Five different water resource management scenarios are examined on eight dry islands of the Aegean Sea in Greece, pitting the current practice of water hauling via ship against alternative water supply schemes in delivering a sustainable solution for meeting water demand. The first scenario employs current water supply practices along with the operation of domestic rainwater harvesting systems. Desalinated water, provided through the operation of wind-powered desalination plants, is considered the main source of potable water in the rest of scenarios. Wind-powered desalination may be combined with rainwater harvesting as a supplementary source of water and/or seawater pumping and an additional source of energy that is supplied to the system. All different alternatives are evaluated for a 30-year lifespan, and an optimal solution is proposed for each island, based on a life cycle cost (LCC) analysis. The performance of this solution is then assessed under six climate change (CC) scenarios in terms of the rate of on-grid versus off-grid renewable energy that is required in order to achieve a certain reliability level. Overall, the examined scenarios show a decreasing performance in terms of reliability under CC for the eight islands.
Ioannis M. Kourtis; Konstantinos G. Kotsifakis; Elissavet G. Feloni; Evangelos A. Baltas. Sustainable Water Resources Management in Small Greek Islands under Changing Climate. Water 2019, 11, 1694 .
AMA StyleIoannis M. Kourtis, Konstantinos G. Kotsifakis, Elissavet G. Feloni, Evangelos A. Baltas. Sustainable Water Resources Management in Small Greek Islands under Changing Climate. Water. 2019; 11 (8):1694.
Chicago/Turabian StyleIoannis M. Kourtis; Konstantinos G. Kotsifakis; Elissavet G. Feloni; Evangelos A. Baltas. 2019. "Sustainable Water Resources Management in Small Greek Islands under Changing Climate." Water 11, no. 8: 1694.
The present work aims at quantifying the benefit of Low Impact Development (LID) practices in reducing peak runoff and runoff volume, and at comparing LID practices to conventional stormwater solutions. The hydrologic-hydraulic model used was the Storm Water Management Model (SWMM5.1). The LID practices modeled were: (i) Green roofs; and (ii) Permeable pavements. Each LID was tested independently and compared to two different conventional practices, i.e., sewer enlargement and detention pond design. Results showed that for small storm events LID practices are comparable to conventional measures, in reducing flooding. Overall, smaller storms should be included in the design process.
Ioannis M. Kourtis; Vassilios A. Tsihrintzis; Evangelos Baltas. Simulation of Low Impact Development (LID) Practices and Comparison with Conventional Drainage Solutions. Proceedings 2018, 2, 640 .
AMA StyleIoannis M. Kourtis, Vassilios A. Tsihrintzis, Evangelos Baltas. Simulation of Low Impact Development (LID) Practices and Comparison with Conventional Drainage Solutions. Proceedings. 2018; 2 (11):640.
Chicago/Turabian StyleIoannis M. Kourtis; Vassilios A. Tsihrintzis; Evangelos Baltas. 2018. "Simulation of Low Impact Development (LID) Practices and Comparison with Conventional Drainage Solutions." Proceedings 2, no. 11: 640.
The present study utilizes nine years of measurements taken from a Joss–Waldvogel disdrometer (JWD). From this dataset, thirty six rainfall events, were selected and categorized, respectively, in convective and stratiform types, according to specific criteria. Six statistical distributions namely the one- and two-parameter exponential, the two- and three-parameter lognormal and finally the two- and three-parameter gamma were fitted on the observed drop size distributions (DSDs). The goodness-of-fit between each statistical and the observed distribution was determined based on the Kolmogorov–Smirnov test. The results show that 72% of the stratiform events are best described by the three-parameter lognormal distribution while 28% are best described by the three-parameter gamma distribution. In the case of convective events, the results are more diversified; the two- and three-parameter gamma distribution fits best in 39% and 17% of the events, respectively, while the two- and three-parameter lognormal distribution fits best in 6% and 39% of the events. The one- and two-parameter exponential distribution was not the best fit in any case. Moreover, initial steps have already been taken in order for these findings to be used for calibration purposes of a recently employed X-band rainscanner in the Attica region in Greece.
Evangelos Baltas; Dimitris Panagos; Maria Mimikou. Statistical Analysis of the Raindrop Size Distribution Using Disdrometer Data. Hydrology 2016, 3, 9 .
AMA StyleEvangelos Baltas, Dimitris Panagos, Maria Mimikou. Statistical Analysis of the Raindrop Size Distribution Using Disdrometer Data. Hydrology. 2016; 3 (1):9.
Chicago/Turabian StyleEvangelos Baltas; Dimitris Panagos; Maria Mimikou. 2016. "Statistical Analysis of the Raindrop Size Distribution Using Disdrometer Data." Hydrology 3, no. 1: 9.
Flood events have often occurred in the metropolitan urban area of Athens, capital of Greece, causing loss of property and in many cases human lives. In this study a flood hazard assessment model for urban areas is examined. The Kifisos and Ilisos Rivers flowing through the plain of Athens was the case study of the present work. The quantitative analysis of the Kifisos and Ilisos Rivers drainage networks was performed to identify flash-flood prone areas. The major factors affecting urban floods were estimated. The slope angle, elevation, distance from open channel streams, distance from totally covered streams, hydro-lithology and land cover of the study area were used. to evaluate these factors the analytical hierarchical process method was applied in a geographical information system. A sensitivity analysis was made to assess the effect of the various factors on the flood hazard map. Three scenarios were developed to examine the effect of uncertainty of the factors’ values to the flood hazard assessment results, leading to the corresponding urban flood hazard assessment maps. The produced map showed that the areas of very high flood hazard are located mostly along the lower reaches of Kifisos and Ilisos Rivers, particularly to the southern and to the western part of the study area. These areas are characterized by lowland morphology, gentle slope, totally covered streams, expansion of impermeable formation and intense urbanization. The uncertainty analysis shows no significant differences on the spatial distribution of the hazard zones. The produced urban flood hazard map proves a satisfactory agreement between the flood hazard zones and the spatial distribution of flood phenomena that have affected the study area in the past 117 years. Furthermore, the comparison between the flood-prone areas that were derived from the geomorphological analysis of the drainage networks and the high flood-hazard zones of the final map indicated reliable results and a high accuracy of the proposed methodology.
G. D. Bathrellos; E. Karymbalis; H. D. Skilodimou; K. Gaki-Papanastassiou; E. A. Baltas. Urban flood hazard assessment in the basin of Athens Metropolitan city, Greece. Environmental Earth Sciences 2016, 75, 1 -14.
AMA StyleG. D. Bathrellos, E. Karymbalis, H. D. Skilodimou, K. Gaki-Papanastassiou, E. A. Baltas. Urban flood hazard assessment in the basin of Athens Metropolitan city, Greece. Environmental Earth Sciences. 2016; 75 (4):1-14.
Chicago/Turabian StyleG. D. Bathrellos; E. Karymbalis; H. D. Skilodimou; K. Gaki-Papanastassiou; E. A. Baltas. 2016. "Urban flood hazard assessment in the basin of Athens Metropolitan city, Greece." Environmental Earth Sciences 75, no. 4: 1-14.
An attempt is made to estimate the basic hydrometeorological variables, namely the rainfall concentration for each bin per m3, the radar reflectivity factor Z and the rainfall intensity R, and consequently to determine coefficient “a” and exponent “b” of the power law relationship Z = aRb. Data used were recorded in a period of almost 10 years, with a Joss-Walvogel RD-69 disdrometer (JWD), located in the meteorological station of the campus of National Technical University of Athens. A number of rainfall events were selected based on the following criteria: the total rainfall depth of each event was greater than 24.0 mm and the average rainfall intensity exceeded 5.0 mm/h, in order to only study events with increased flash flooding probability. Initially, Drop Size Distributions (DSDs) were calculated for these rainfall events and processed for the derivation of Z-R relationships. Such Z-R relationships were finally derived for the overall spectra of R > 5.0 mm/h and for each event separately and were compared with other Z-R relationships found in the literature.
E. A Baltas; D. S. Panagos; M. A. Mimikou. An Approach for the Estimation of Hydrometeorological Variables Towards the Determination of Z-R Coefficients. Environmental Processes 2015, 2, 751 -759.
AMA StyleE. A Baltas, D. S. Panagos, M. A. Mimikou. An Approach for the Estimation of Hydrometeorological Variables Towards the Determination of Z-R Coefficients. Environmental Processes. 2015; 2 (4):751-759.
Chicago/Turabian StyleE. A Baltas; D. S. Panagos; M. A. Mimikou. 2015. "An Approach for the Estimation of Hydrometeorological Variables Towards the Determination of Z-R Coefficients." Environmental Processes 2, no. 4: 751-759.
Τhis research aims at the precise estimation of solar radiation, on an hourly and daily basis, by using measured data of solar radiation and sunshine duration. Data is collected from the automatic meteorological station of Amynteo, West Macedonia, Greece. For the correlation of solar radiation and sunshine duration, the Angström–Prescott equation is selected. Two limit conditions of cloud coverage are examined, overcast and clear sky, for the estimation of the factors as and bs of the Angström–Prescott equation. The factor as is the minimum transmissivity for overcast sky, while as + bs is expressing the clear sky transmissivity. In addition, spectral analysis is performed to investigate the periodicities of the factors as and bs. The Lomb–Scargle periodogram is applied, as data are unevenly distributed in time, and reveals the existence of two periodicities for the bs factor. More specifically, annual periodicity with an estimated width equal to 0.032, and daily periodicity with a width equal to 0.184. As a result of this research, a sinusoidal equation with two harmonics is developed to calculate the bs factor, which coincides with the clearness index (Rs/Ra) under clear sky. In overcast conditions, the clearness index does not exhibit periodicities. The derived equation is used to produce estimations of solar radiation values on an hourly and daily basis. The daily values estimated from the new equation gives better results when compared to typical regression analysis.
Vasilios Ambas; Evangelos Baltas. Spectral Analysis of Hourly Solar Radiation. Environmental Processes 2014, 1, 251 -263.
AMA StyleVasilios Ambas, Evangelos Baltas. Spectral Analysis of Hourly Solar Radiation. Environmental Processes. 2014; 1 (3):251-263.
Chicago/Turabian StyleVasilios Ambas; Evangelos Baltas. 2014. "Spectral Analysis of Hourly Solar Radiation." Environmental Processes 1, no. 3: 251-263.
The present research was conducted at an experimental watershed in the prefecture of Attica, Greece, using the selected observed rainfall-runoff events from a four-year time period. The objectives of this study were two: The first was the determination of the initial abstraction Ia – watershed storage S ratio. The average ratio (Ia/S) was equal to 0.014. The corresponding ratio at a subwatershed was 0.037. The difference was attributed to the different spatial distribution of landuses at the extent of the watershed. The second objective of the study was to examine the effect of the SCS empirical equation on hydrograph simulation. This was investigated through the comparison between the observed and two different simulated hydrographs at each one out of eighteen selected storm events. The simulated hydrographs were calculated by applying on the watershed's unit hydrograph two time distributions of excess rainfall that derived from the SCS method using two different approaches. In the first approach, the initial abstraction was determined from the observed rainfall-runoff data, while in the second, it was calculated using the SCS empirical equation. It was found that the SCS empirical equation estimates greater amount of initial abstraction and leads to the delayed start of the excess rainfall and the simulated runoff. This resulted in the overestimation of the peak flow rate and the time to peak at the majority of the storm events.
E. A. Baltas; N. A. Dervos; M. A. Mimikou. Research on the initial abstraction – storage ratio and its effect on hydrograph simulation at a watershed in Greece. Hydrology and Earth System Sciences Discussions 2007, 1 .
AMA StyleE. A. Baltas, N. A. Dervos, M. A. Mimikou. Research on the initial abstraction – storage ratio and its effect on hydrograph simulation at a watershed in Greece. Hydrology and Earth System Sciences Discussions. 2007; ():1.
Chicago/Turabian StyleE. A. Baltas; N. A. Dervos; M. A. Mimikou. 2007. "Research on the initial abstraction – storage ratio and its effect on hydrograph simulation at a watershed in Greece." Hydrology and Earth System Sciences Discussions , no. : 1.
In this paper an integrated system, named HydroGeologist was developed in Delphi 5 and runs under Windows Operating System with minimal requirements in hardware resources, in order to support the storage and analysis requirements for all hydrogeological information belonging to different public sectors. The data are stored in a distributed Oracle 8i database with embedded security and charging policies. The data search in the database is user friendly and facilitates any search queries for any field in any table of the database without any SQL knowledge. HydroGeologist can produce graphs of time series; calculate time series trend lines and statistical parameters. Geological Cross-Sections are generated on the fly from geological data and the user can change the symbols used for stones, filters or gravel packs easily. Calculation of hydrogeological parameters (T,K,S,R) from pump tests is easy, intuitive and fully parameterized. HydroGeologist can export and import its raw and processed data easily to ASCII text files and communicate with MS Office applications. HydroGeologist can also produce input files for other well-known applications such as ModFlow or Arcview.
E. A. Baltas; A. M. Gkikas; M. A. Mimikou. An Integrated System for Management and Processing of Hydrogeological Data. World Water & Environmental Resources Congress 2003 2003, 1 .
AMA StyleE. A. Baltas, A. M. Gkikas, M. A. Mimikou. An Integrated System for Management and Processing of Hydrogeological Data. World Water & Environmental Resources Congress 2003. 2003; ():1.
Chicago/Turabian StyleE. A. Baltas; A. M. Gkikas; M. A. Mimikou. 2003. "An Integrated System for Management and Processing of Hydrogeological Data." World Water & Environmental Resources Congress 2003 , no. : 1.
A hydrometerological study in a river basin was conducted to demonstrate the use of a weather radar for rainfall and flood-flow forecasting. The study region is a Pinioç river subbasin with a drainage area of 2,763 km 2 located in central Greece. Six storm events that created flash floods were recorded every 10–30 min, and were analyzed and processed in terms of ground clutter supression, anomalous propagation, beam refraction, and the losses and merging procedures of radar and rain-gauge rainfall data. A rainfall-runoff model for flood-flow forecasting based on the unit hydrograph theory was then applied twice. First, by using as input the mean areal rain-gauge rainfall derived by applying the Thiessen polygon method and second, by applying the mean areal radar rainfall information over the basin. It was found that the model performs better when it uses processed weather radar data as input. Results of using as input oneand two-hour forecasted rainfall for flood forecasting were encouraging.
M. A. Mimikou; E. A. Baltas. Flood Forecasting Based on Radar Rainfall Measurements. Journal of Water Resources Planning and Management 1996, 122, 151 -156.
AMA StyleM. A. Mimikou, E. A. Baltas. Flood Forecasting Based on Radar Rainfall Measurements. Journal of Water Resources Planning and Management. 1996; 122 (3):151-156.
Chicago/Turabian StyleM. A. Mimikou; E. A. Baltas. 1996. "Flood Forecasting Based on Radar Rainfall Measurements." Journal of Water Resources Planning and Management 122, no. 3: 151-156.
This paper describes the application of the HEClF conceptual model for flood-flow forecllllting and warning to the Venetikos river basin in Northwestern Greece, a region suffering from frequent and hazardous Bash floods. The extremely uneven and nonuniform spatial rainfall distribution in the study region forced the modification of the initial lumped version of the model and its application in a semidistributed manner, Such as by dividing the entire basin into three subbasins with different geomorphology and spatial rainfall patterns. The model is shown to perform better in the semidistributed than in the lumped mode, thus juatifying the modifications adopted and supporting application of the flood-flow forecasting model in a fully distributed manner on a 4x4 km2 grid network combined with omite and remotely .ensed radar rainfall input information. Preliminary results from current research on thi. integrated application suggest that the model’s forecasting performance may be further improved.
M.A. Mimikou; E.A. Baltas; M. Borga. Improving The Efficiency Of The Hec1f Model In Flood-Flow Forecasting. International Journal of Modelling and Simulation 1995, 15, 30 -37.
AMA StyleM.A. Mimikou, E.A. Baltas, M. Borga. Improving The Efficiency Of The Hec1f Model In Flood-Flow Forecasting. International Journal of Modelling and Simulation. 1995; 15 (1):30-37.
Chicago/Turabian StyleM.A. Mimikou; E.A. Baltas; M. Borga. 1995. "Improving The Efficiency Of The Hec1f Model In Flood-Flow Forecasting." International Journal of Modelling and Simulation 15, no. 1: 30-37.