Testing optically stimulated luminescence dating on sand-sized quartz of deltaic deposits from the Sperchios delta plain, central Greece

This study reports on the first investigation into the potential of luminescence dating to establish a chronological framework for the depositional sequences of the Sperchios delta plain, central Greece. A series of three borehole cores (20 m deep) and two shallow cores (4 m deep), from across the delta plain, were extracted, and samples were collected for luminescence dating. The luminescence ages of sand-sized quartz grains were obtained from small aliquots of quartz, using the Single-Aliquot Regenerative-dose (SAR) protocol. The equivalent dose determination included a series of tests and the selection of the Minimum Age Model (MAM) as the most appropriate statistical model. This made it possible to confirm the applicability of quartz Optically Stimulated Luminescence (OSL) dating to establish absolute chronology for deltaic sediments from the Sperchios delta plain.Testing age results of the five cores showed that the deltaic sediments were deposited during the Holocene. A relatively rapid deposition is implied for the top ∼14 m possibly as a result of the deceleration in the rate of the sea-level rise and the transition to terrestrial conditions, while on the deeper parts, the reduced sedimentation rate may indicate a lagoonal or coastal environment

Determination of environmental flows in rivers using an integrated hydrological-hydrodynamic-habitat modelling approach

[EN] We propose the novel integrated modelling procedure 3H-EMC for the determination of the environmental flow in rivers and streams; 3H-EMC combines Hydrological, Hydrodynamic and Habitat modelling with the use of the Environmental Management Classes (EMCs) that are defined by the Global Environmental Flow Calculator. We apply 3H-EMC in the Sperchios River in Central Greece, in which water abstractions for irrigation cause significant environmental impacts. Calculations of the hydrodynamic-habitat model, in which the large and the small chub are the main fish species, suggest discharge values that range from 1.0 m3/s to 4.0 m3/s. However, hydrological modelling indicates that it is practically difficult to achieve discharges that are higher than approximately 1.0-1.5 m3/s. Furthermore, legislation suggests significantly lower values (0.4-0.5 m3/s) that are unacceptable from the ecological point of view. This behaviour shows that a non-integrated approach, which is based only on hydrodynamic-habitat modelling does not necessarily result in realistic environmental flows, and thus an integrated approach is required. We propose the value of 1.0 m3/s as the "optimum" environmental flow for Sperchios River, because (a) it satisfies the habitat requirements, as expressed by the values of weighted useable area that are equal to 2180 and 1964 m2 for the large and small chub, respectively, and correspond to 82 and 95% of their respective maximum values, (b) it is consistent with the requirements of Environmental Classes A and B, whose percentiles are higher than 75% for discharge (77.2%) and for habitat availability (>83.5% for the large chub and >85.0% for the small chub), (c) it is practically achievable from the hydrological point of view, and (d) it is higher than the value proposed by the Greek legislation. The proposed modelling approach can be applied to any river or stream using the same or similar modelling tools, which should be linked via suitable coupling algorithms.Hydraulic field measurements were performed within the framework of a research project by the Hellenic Centre of Marine Research (HCMR) entitled KRIPIS “Development of an integrated management system for river basin, coastal and marine zones” (http://imbriw.hcmr.gr/en/). Fish habitat data were collected within the framework of the ECOFLOW research project (www. ecoflow.gr). A part of the modelling work has been performed, while the first author was a visiting professor at the Technical University of Munich (TUM); thanks are due to the Bavarian State Ministry of Education and Cultural Affairs and the German Academic Exchange Service (DAAD).Stamou, A.; Polydera, A.; Papadonikolaki, G.; Martinez-Capel, F.; Muñoz Mas, R.; Papadaki, C.; Zogaris, S.... (2018). Determination of environmental flows in rivers using an integrated hydrological-hydrodynamic-habitat modelling approach. Journal of Environmental Management. 209:273-285. https://doi.org/10.1016/j.jenvman.2017.12.038S27328520

Desarrollo de modelos de idoneidad de hábitat para la trucha balcánica (Salmo fariodes, Karaman) y estimación de caudales ecológicos en ríos de montaña de Grecia

[EN] Esta investigación, enmarcada en el proyecto ECOFLOW (Grecia), está enfocada a la estimación de caudales ecológicos en ríos de Grecia. La alteración hidrológica y la degradación de los hábitats fluviales han sido escasamente estudiados en este país, y permanecen aún fuera de su legislación. En este trabajo se aplicó el enfoque de la simulación del hábitat físico, basado en simulación hidráulica y del hábitat. Por primera vez para la trucha balcánica occidental (Salmo fariodes, Karaman) adulta, se realizó un modelo de idoneidad del hábitat multivariante (a escala de microhábitat) mediante modelos generalizados aditivos (GAM). Dichos adultos escogían principalmente los microhábitats con escasa corriente, profundos y con abundante refugio. Un tramo del río Acheloos se escogió para la simulación del hábitat físico. La falta de hábitats con abundante refugio y las pozas poco desarrolladas no llegaron a aportar una idoneidad alta. Esta primera aplicación en Grecia remarca la necesidad de ampliar y extender los enfoques de caudales ecológicos basados en estudios científicos locales y regionales, basados en hidrología y en eco-hidráulica. Estos métodos suponen avances importantes y son relevantes para mejorar el estado ecológico de los ríos y para la aplicación de las actuales políticas europeas sobre el agua.Este estudio se enmarca dentro del proyecto ECOFLOW patrocinado por la Secretaría General Griega para la investigación y la Tecnología en el marco de NSRF 2007-2013.Papadaki, C.; Muñoz Mas, R.; Ntoanidis, L.; Martínez Capel, F.; Zogaris, S.; Dimitriou, E. (2015). Desarrollo de modelos de idoneidad de hábitat para la trucha balcánica (Salmo fariodes, Karaman) y estimación de caudales ecológicos en ríos de montaña de Grecia. Cuadernos de la Sociedad Española de Ciencias Forestales. (41):253-268. http://hdl.handle.net/10251/60208S2532684

Nitrate isotopes in catchment hydrology: insights, ideas and implications for models

Models that simulate water flow and quality, particularly related to nitrate ions, are commonly used on a catchment-scale. However, tracking nitrate ions is a challenging task due to the intricate processes that affect them, such as phase exchanges, transformations, and interactions with various environmental media. In general, models capable of carrying out all tasks required to simulate water flow and quality at the same time, are rare. Additionally, most available models focus only on specific compartments of the watershed, such as surface water, topsoil, unsaturated zone, or groundwater. Taken together, these two challenges can lead to oversimplified representations of a system’s hydrology, as catchment internal processes become neglected due to missing information (lack of informative measurements, or models not focusing on all watershed compartments). Attempting to combine these models or to couple different watershed compartments results in complex calculations, increased run times, and a large number of parameters to estimate. Artificial Intelligence (AI) models have been massively used in environmental studies but, so far, the majority of them have been tested theoretically and not under real conditions. To overcome these challenges, stable isotope data are often employed to calibrate and validate internal catchment processes of these models. While water stable isotopes (δ18O and δ2H of H2O) have been extensively used in many water flow models, the use of nitrate isotopes (δ15N and δ18O of NO3-) in water quality models remains poorly explored. Nitrate isotopes can help trace the origin of NO3- contamination and disentangle the complex reactions and dynamics that nitrate undergoes during transport. Hence, we propose that incorporating nitrate isotopes into catchment-scale water flow and quality models can substantially enhance the accuracy of these models. This review provides an overview of the current use of catchment hydrological models in predicting flow and fate of solutes. We discuss their limitations and highlight the potential of combining these models with nitrate isotopes. Ultimately, this approach may reduce prediction uncertainties and provide more effective guidance for water management decisions

Potential impacts of climate change on flow regime and fish habitat in mountain rivers of the southwestern Balkans

The climate change in the Mediterranean area is expected to have significant impacts on the aquatic ecosystems and particular in the mountain rivers and streams that often host important species such as the Salmo farioides, Karaman 1938. These impacts will most possibly affect the habitat availability for various aquatic species resulting to an essential alteration of the water requirements, either for dams or other water abstractions, in order to maintain the essential levels of ecological flow for the rivers. The main scope of this study was to assess potential climate change impacts on the hydrological patterns and typical biota for a south-western Balkan mountain river, the Acheloos. The altered flow regimes under different emission scenarios of the Intergovernmental Panel on Climate Change (IPCC) were estimated using a hydrologicalmodel and based on regional climate simulations over the study area. The Indicators of Hydrologic Alteration (IHA) methodology was then used to assess the potential streamflow alterations in the studied river due to predicted climate change conditions. A fish habitat simulation method integrating univariate habitat suitability curves and hydraulic modeling techniques were used to assess the impacts on the relationships between the aquatic biota and hydrological status utilizing a sentinel species, the West Balkan trout. The most prominent effects of the climate change scenarios depict severe flow reductions that are likely to occur especially during the summer flows, changing the duration and depressing the magnitude of the natural low flow conditions. Weighted Usable Area-flow curves indicated the limitation of suitable habitat for the native trout. Finally, this preliminary application highlighted the potential of science-based hydrological and habitat simulation approaches that are relevant to both biological quality elements (fish) and current EUWater policy to serve as efficient tools for the estimation of possible climate change impacts on the south-western Balkan river ecosystems.This study was supported by the ECOFLOW project funded by the Hellenic General Secretariat of Research and Technology in the framework of the NSRF 2007-2013. The W. B. trout data collection was partially funded by the Spanish Ministry of Economy and Competitiveness with the project SCARCE (Consolider-Ingenio 2010 CSD2009-00065).Papadaki, C.; Soulis, K.; Muñoz Mas, R.; Martinez-Capel, F.; Zogaris, S.; Ntoanidis, L.; Dimitriou, E. (2016). Potential impacts of climate change on flow regime and fish habitat in mountain rivers of the southwestern Balkans. Science of the Total Environment. 540:418-428. https://doi.org/10.1016/j.scitotenv.2015.06.134S41842854

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Precipitation Trends and Flood Hazard Assessment in a Greek World Heritage Site

Natural disasters have become more frequent and intense over the last decade mainly as a result of poor water and land management. Cultural sites and monuments are extremely vulnerable to natural disasters, particularly floods, while mitigation measures and protective infrastructure are difficult to construct within such areas. In the present study, the precipitation trends of the recent past and over the next 80 years were analyzed for the old town of Corfu (UNESCO World Heritage Site) in order to identify potentially significant changes that may affect the flood risk of the area. Moreover, a multi-criteria analysis using GIS software was used to identify high flood hazard zones in this living monument in order to propose specific mitigation measures that are in line with the characteristics of the site. The main effort in this study was to find a methodological approach for a fast but reliable assessment of future changes in the flood risk of historic monuments without the need for a hydrodynamic model and with a limited amount of locally based data. With the selected approach, a good indication of the potential changes in flood risk was provided, according to climate scenarios and simple, physically-based geostatistical models. The results indicate that no significant changes in the flood risk were found for the future climatic conditions, and the identified flood-prone areas will remain approximately the same as today in this particular historic monument. The uncertainty that is included in this output originates mainly from the inherent errors in climate modeling and from the non-high temporal resolution of the data

Differentiation in Aquatic Metabolism between Littoral Habitats with Floating-Leaved and Submerged Macrophyte Growth Forms in a Shallow Eutrophic Lake

The metabolic balance between gross primary production (GPP) and ecosystem respiration (R) is known to display large spatial and temporal variations within shallow lakes. Thus, although estimation of aquatic metabolism using free-water measurements of dissolved oxygen concentration has become increasingly common, the explanation of the variance in the metabolic regime remains an extremely difficult task. In this study, rates of GPP, respiration (R) and the metabolic balance (net ecosystem production, NEP) were estimated in four littoral habitats with different macrophyte growth forms (floating-leaved vs submerged) over a 28-month period in lake of Kastoria (Greece), a shallow eutrophic lake. Our results showed that net heterotrophy prevailed over the studied period, suggesting that allochthonous organics fuel respiration processes in the littoral. Temporal variation in the metabolic rates was driven mainly by the seasonal variation in irradiance and water temperature, with the peak of metabolic activity occurring in summer and early autumn. Most importantly, significant spatial variation among the four habitats was observed and associated with the different macrophyte growth forms that occurred in the sites. The results highlight the importance of habitat specific characteristics for the assessment of metabolic balance and underline the potentially high contribution of littoral habitats to the whole lake metabolism