FUTURE ESTIMATIONS OF TEMPERATURE CHANGE OVER CENTRAL PINDUS UNTIL THE END OF THE 21TH CENTURY USING REGIONAL CLIMATE MODELS OF ENSEMBLES

  Στην παρούσα εργασία αξιολογείται η καταλληλότητα των περιοχικών κλιματικών μοντέλων (RCMs) να προσομοιώνουν τις θερμοκρασίες του αέρα στον ορεινό όγκος της κεντρικής Πίνδου. Για τον σκοπό αυτό χρησιμοποιήθηκαν μετεωρολογικοί σταθμοί που βρίσκονται στον ορεινό χώρο και διαθέτουν μακροχρόνιες χρονοσειρές θερμοκρασίας καθώς και δεδομένα από το ευρωπαϊκού προγράμμα ENSEMBLES. Κατά την αξιολόγηση συγκρίθηκαν τα δεδομένα των σταθμών με το κοντινότερο σημείο πλέγματος των RMCs για την περίοδο βάσης 1974-2000. Ως δείκτης αξιολόγησης χρησιμοποιήθηκε η Τετραγωνικής Ρίζας του Μέσου Τετραγωνικού Σφάλματος (RMSE). Από την αξιολόγηση προέκυψε πως καλύτερη προσομοίωση της θερμοκρασίας παρουσιάζει το μοντέλο ICTP (RegCM3) και έπεται το μοντέλο του HC (METO- HC_HadR M3Q0). Τέλος σε ότι αφορά τις μελλοντικές εκτιμήσεις για την περίοδο 2074-2100 καταγράφονταί τάσεις αύξησεις της μηνιαίας θερμοκρασίας που γίνεται εντονότερη του χειμαρινούς μήνες και για τα δύο μοντέλα.In this study the ability of regional climate models (RCMs) to represent temperature condition over mountainous area of central Pindus were evaluated. In order to achieve the goals of the current research, temperature data from mountainous meteorological stations with long-term time series and data from the European project ENSEMBLES were used. During the evaluation process temperature data from meteorological stations were compared with data from the nearest grid point of RCMs, for the base period 1974-2000. As evaluator indexes RMSE, MAE and BIAS were used. The results showed that best simulations were made from the model ICTP (RegCM3) and followed the model HC (METO- HC HadR M3Q0). Finally, regarding the future estimations for the period 2074-2100, increase trend in monthly temperature was recorded around 3,7 0C according the first model and 4,8 0C due the second one, evenly distributed through the months of the year

ESTIMATION OF SOIL EROSION IN MOUNTAINOUS WATERSHEDS WITH THE COMBINED USE OF RUSLE MODEL AND GEOGRAPHIC INFORMATION SYSTEMS

Στην παρούσα εργασία εφαρμόστηκε η μέθοδος RUSLE για την εκτίμηση της μέσης ετήσιας εδαφικής διάβρωσης στη λεκάνη απορροής του χειμάρρου Κλεινοβίτικου του Νομού Τρικάλων χρησιμοποιώντας τα Γεωγραφικά Συστήματα Πληροφοριών. Για τον ακριβέστερο και ταχύτερο υπολογισμό της μεθόδου αναπτύχθηκε εργαλείο στο περιβάλλον Model Builder, μία εφαρμογή του ArcGIS που επιτρέπει τη δημιουργία, επεξεργασία και διαχείριση μαθηματικών μοντέλων. Τα κυριότερα πλεονεκτήματα από τη χρήση του Model Builder για την εφαρμογή του μοντέλου της RUSLE είναι ότι επιταχύνονται οι υπολογισμοί, μειώνεται ο χρόνος και το κόστος εργασίας.This paper deals with the implementation of RUSLE method for the estimation of the mean annual soil erosion in Klinovitikos watershed at Trikala Prefecture using Geographical Information Systems. For more accurate and faster results, a GIS tool was developed in Model Builder environment, an application that allows the creation, editing and management of mathematical models. The main advantages of using Model Builder so as to estimate erosion with the RUSLE method is that accelerates calculation and reduces cost and time

ΥΔΡΟΛΟΓΙΚΗ ΑΠΟΚΡΙΣΗ ΤΗΣ ΛΕΚΑΝΗΣ ΑΠΟΡΡΟΗΣ ΤΟΥ ΧΕΙΜΑΡΡΟΥ «ΜΠΑΣΔΕΚΗ» ΟΛΥΜΠΙΑΔΑΣ ΣΤΗΝ ΚΑΤΑΙΓΙΔΑ ΤΗΣ 25ης ΝΟΕΜΒΡΙΟΥ 2019

Στις 25 Νοεμβρίου του 2019, ισχυρή βροχόπτωση με υψηλή ραγδαιότητα έπληξε την Ανατολική Χαλκιδική που είχε ως αποτέλεσμα καταστροφικά πλημμυρικά φαινόμενα. Στην παρούσα εργασία αναλύεται η απόκριση της λεκάνης απορροής του χειμάρρου «Μπασδέκη», κοντά στον οικισμό της Ολυμπιάδας, κατά την διάρκεια του φαινομένου.  Για τον σκοπό αυτό εκτιμήθηκε η απορροϊκή βροχόπτωση με την μέθοδο του απορροϊκού συντελεστή Curve Number (CN) και το υδρογράφημα της πλημμύρας με τη χρήση του συνθετικού μοναδιαίου υδρογραφήματος της Soil Conservation Service (SCS). Επίσης, εφαρμόστηκε η μέθοδος των Stiny - Herheulidze για τον υπολογισμό της στερεοπαροχής. H μέγιστη πλημμυρική αιχμή εκτιμήθηκε ίση με 140,7 m3/sec και η στερεοπαροχή ίση με 44,8 m3/sec. Οι παραπάνω τιμές δεν μπόρεσαν να διοχετευτούν και το νερό υπερχείλισε από την κοίτη του χειμάρρου. Από την ανάλυση των παραγόντων πλημμυρογένεσης προέκυψε ότι η ραγδαιότητα της βροχόπτωσης και ο διαποτισμός του εδάφους, από τις βροχοπτώσεις προηγούμενων ημερών, συνέβαλαν στην δημιουργία του έντονου πλημμυρικού φαινομένου στην Ολυμπιάδα. Τα αποτελέσματα της παρούσας εργασίας συμβάλουν στην  κατανόηση των αιτιών και του μηχανισμού λειτουργίας των πλημμυρικών φαινομένων στα χειμαρρικά ρεύματα

The development and demonstration of an enhanced risk model for the evacuation process of large passenger vessels

Evacuating a large and complex environment, such as a large passenger vessel, either cruise or RoPax, is a safety-critical task that involves thousands of people in motion and a complex decision-making process. Despite the significant enhancement of maritime safety over the years, various hazards still pose threats to passengers and crew. To deal with this reality, the SafePASS project radically redefines the evacuation process by introducing novel technological solutions. In this context, this paper presents, in detail, an enhanced risk model for the ship evacuation process in order to facilitate the understanding of the actual risks of the process in fire and flooding accidents, and to assess various risk control measures and options toward risk mitigation. The risk model covers the entire event sequence in emergency cases on board, until the survival at sea phase, and it is constructed in two levels, following a combination of event tree analysis and Bayesian networks. Results show the risk corresponds to baseline scenarios for each accident case, which are also verified by relevant IMO and EMSA studies, and an example case of risk control option (RCO) is introduced to the model to demonstrate its ability to assess RCO’s efficiency in terms of risk reduction

The development and demonstration of an enhanced risk model for the evacuation process of large passenger vessels

Evacuating a large and complex environment, such as a large passenger vessel, either cruise or RoPax, is a safety-critical task that involves thousands of people in motion and a complex decision-making process. Despite the significant enhancement of maritime safety over the years, various hazards still pose threats to passengers and crew. To deal with this reality, the SafePASS project radically redefines the evacuation process by introducing novel technological solutions. In this context, this paper presents, in detail, an enhanced risk model for the ship evacuation process in order to facilitate the understanding of the actual risks of the process in fire and flooding accidents, and to assess various risk control measures and options toward risk mitigation. The risk model covers the entire event sequence in emergency cases on board, until the survival at sea phase, and it is constructed in two levels, following a combination of event tree analysis and Bayesian networks. Results show the risk corresponds to baseline scenarios for each accident case, which are also verified by relevant IMO and EMSA studies, and an example case of risk control option (RCO) is introduced to the model to demonstrate its ability to assess RCO’s efficiency in terms of risk reduction

Prediction of High-Grade Vesicoureteral Reflux after Pediatric Urinary Tract Infection: External Validation Study of Procalcitonin-Based Decision Rule

BACKGROUND: Predicting vesico-ureteral reflux (VUR) 653 at the time of the first urinary tract infection (UTI) would make it possible to restrict cystography to high-risk children. We previously derived the following clinical decision rule for that purpose: cystography should be performed in cases with ureteral dilation and a serum procalcitonin level 650.17 ng/mL, or without ureteral dilatation when the serum procalcitonin level 650.63 ng/mL. The rule yielded a 86% sensitivity with a 46% specificity. We aimed to test its reproducibility. STUDY DESIGN: A secondary analysis of prospective series of children with a first UTI. The rule was applied, and predictive ability was calculated. RESULTS: The study included 413 patients (157 boys, VUR 653 in 11%) from eight centers in five countries. The rule offered a 46% specificity (95% CI, 41-52), not different from the one in the derivation study. However, the sensitivity significantly decreased to 64% (95%CI, 50-76), leading to a difference of 20% (95%CI, 17-36). In all, 16 (34%) patients among the 47 with VUR 653 were misdiagnosed by the rule. This lack of reproducibility might result primarily from a difference between derivation and validation populations regarding inflammatory parameters (CRP, PCT); the validation set samples may have been collected earlier than for the derivation one. CONCLUSIONS: The rule built to predict VUR 653 had a stable specificity (ie. 46%), but a decreased sensitivity (ie. 64%) because of the time variability of PCT measurement. Some refinement may be warranted

Effect of Climate Change on Soil Erosion in a Mountainous Mediterranean Catchment (Central Pindus, Greece)

The aim of this study was to assess soil erosion changes in the mountainous catchment of the Portaikos torrent (Central Greece) under climate change. To this end, precipitation and temperature data were derived from a high-resolution (25 × 25 km) RegCM3 regional climate model for the baseline period 1974–2000 and future period 2074–2100. Additionally, three GIS layers were generated regarding land cover, geology, and slopes in the study area, whereas erosion state was recognized after field observations. Subsequently, the erosion potential model (EPM) was applied to quantify the effects of precipitation and temperature changes on soil erosion. The results showed a decrease (−21.2%) in annual precipitation (mm) and increase (+3.6 °C) in mean annual temperature until the end of the 21st century, and the above changes are likely to lead to a small decrease (−4.9%) in soil erosion potential

Precipitation and Potential Evapotranspiration Temporal Variability and Their Relationship in Two Forest Ecosystems in Greece

The assessment of drought conditions is important in forestry because it affects forest growth and species diversity. In this study, temporal variability and trends of precipitation (P), potential evapotranspiration (PET), and their relationship (P/PET) were examined in two selected forest ecosystems that present different climatic conditions and vegetation types due to their location and hypsometric zone. The study area includes the forests of Pertouli and Taxiarchis, which are managed by the Aristotle University Forest Administration and Management Fund. The Pertouli is a coniferous forest in Central Greece with a maximum elevation of 2073 m a.s.l, and Taxiarchis is a broadleaved forest in Northern Greece with a maximum elevation of 1200 m a.s.l. To accomplish the goals of the current research, long–term (1974–2016) monthly precipitation and air temperature data from two mountainous meteorological were collected and processed. The PET was estimated using a parametric model based on simplified formulation of the Penman–Monteith equation rather than the commonly used Thornthwaite approach. Seasonal and annual precipitation, potential evapotranspiration (PET), and their ratio (P/PET) values were subjected to Mann–Kendall tests to assess the possible upward or downward trends, and Sen’s slope method was used to estimate the trends magnitude. The results indicated that the examined climatic variables vary greatly between seasons. In general, negative trends were detected for the precipitation time series of Pertouli, whereas positive trends were found in Taxiarchis; both were statistically insignificant. In contrast, statistically significant positive trends were reported for PET in both forest ecosystems. These circumstances led to different drought conditions between the two forests due to the differences of their elevation. Regarding Pertouli, drought trend analysis indicated downward trends for annual, winter, spring, and summer values, whereas autumn showed a slight upward trend. In addition, the average magnitude trend per decade was approximately −2.5%, −3.5%, +4.8%, −0.8%, and +3.3% for annual, winter, autumn, spring, and summer seasons, respectively. On the contrary, the drought trend and the associated magnitude per decade for the Taxiarchis forest were found to be as follows: annual (+2.2%), winter (+6.2%), autumn (+9.2%), spring (+1.0%), and summer (−5.0%). The performed statistical test showed that the reported trend was statistically insignificant at a 5% significance level. These results may be a useful tool as a forest management practice and can enhance the adaptation and resilience of forest ecosystems to climate change

Spatial and Temporal Rainfall Variability over the Mountainous Central Pindus (Greece)

In this study, the authors evaluated the spatial and temporal variability of rainfall over the central Pindus mountain range. To accomplish this, long-term (1961–2016) monthly rainfall data from nine rain gauges were collected and analyzed. Seasonal and annual rainfall data were subjected to Mann–Kendall tests to assess the possible upward or downward statistically significant trends and to change-point analyses to detect whether a change in the rainfall time series mean had taken place. Additionally, Sen’s slope method was used to estimate the trend magnitude, whereas multiple regression models were developed to determine the relationship between rainfall and geomorphological factors. The results showed decreasing trends in annual, winter, and spring rainfalls and increasing trends in autumn and summer rainfalls, both not statistically significant, for most stations. Rainfall non-stationarity started to occur in the middle of the 1960s for the annual, autumn, spring, and summer rainfalls and in the early 1970s for the winter rainfall in most of the stations. In addition, the average magnitude trend per decade is approximately −1.9%, −3.2%, +0.7%, +0.2%, and +2.4% for annual, winter, autumn, spring, and summer rainfalls, respectively. The multiple regression model can explain 62.2% of the spatial variability in annual rainfall, 58.9% of variability in winter, 75.9% of variability in autumn, 55.1% of variability in spring, and 32.2% of variability in summer. Moreover, rainfall spatial distribution maps were produced using the ordinary kriging method, through GIS software, representing the major rainfall range within the mountainous catchment of the study area

Effect of Climate Change on Soil Erosion in a Mountainous Mediterranean Catchment (Central Pindus, Greece)

The aim of this study was to assess soil erosion changes in the mountainous catchment of the Portaikos torrent (Central Greece) under climate change. To this end, precipitation and temperature data were derived from a high-resolution (25 × 25 km) RegCM3 regional climate model for the baseline period 1974–2000 and future period 2074–2100. Additionally, three GIS layers were generated regarding land cover, geology, and slopes in the study area, whereas erosion state was recognized after field observations. Subsequently, the erosion potential model (EPM) was applied to quantify the effects of precipitation and temperature changes on soil erosion. The results showed a decrease (−21.2%) in annual precipitation (mm) and increase (+3.6 °C) in mean annual temperature until the end of the 21st century, and the above changes are likely to lead to a small decrease (−4.9%) in soil erosion potential