Assessing the Ecological Water Level: The Case of Four Mediterranean Lakes

Petriki, O., D. Zervas, Ch. Doulgeris, D. Bobori. 2020. Assessing the Ecological Water Level: The Case of Four Mediterranean Lakes. Water: 12, 2977. doi:10.3390/w12112977The ecological water regime in lake water bodies refers to the water levels that enable the fulfillment of the ecosystem’s multiple functions. Therefore, assessing the ecological water regime necessitates the consideration of hydrological, economic, social, and ecological factors. The present research is focused on the assessment of the ecological water level of four Mediterranean natural lake ecosystems, considering their morphological and biological features. Initially, suggestions on the ecological water regime of the studied lakes were made based on an analysis of the lakes’ morphometry. Further, the ecological and biological requirements of the present fish fauna and aquatic macrophytic vegetation were considered. For the latter, mapping was conducted by extensive sampling according to international standards, in order to assess macrophyte composition, abundance, and chorology, as well as species sensitivity to water level fluctuations. The above guided the proposals on the optimal water level regime that should be met by each lake regarding the macrophytic and fish communities’ sustainability, also taking into account the unique hydromorphological features of each lake. The di erences in the outcoming results revealed that hydromorphological and biological approaches should be combined for assessing lakes’ ecological water regime

Modelling & integration of advanced propulsion systems

This research study focuses on the design of advanced propulsion cycles, having as primary design goal the improvement on noise emissions and fuel consumption. In this context, a preliminary cycle design method has been developed and applied on four novel propulsion systems; ultra high bypass ratio, recuperated, intercooled-recuperated, constant volume combustion turbofans. The analysis has shown significant improvement in jet noise, and fuel consumption, as a result of high bypass ratio. Additionally, a comparison to future fuel-optimised cycle has revealed the trade-off between noise emissions and fuel consumption, where a reduction of ~30dBs in jet noise may be achieved in the expense of ~10% increase of mission fuel. A second aspect of this study is the integration of the propulsion system for improving fan noise. A novel approach is followed, by half-embedding the turbofan in the upper surface of the wing of a Broad Delta airframe. Such an installation aids in noise reduction, by providing shielding to component (fan) noise. However, it leads to significant inlet distortion levels. In order to assess the effect of installation-born distortion on performance an enhanced fan representation model has been developed, able to predict fan and overall engine performance sensitivity to three-dimensional distorted inlet flow. This model that comprises parallel compressor theory and streamline curvature compressor modelling, has been used for proving a linear relation between the loss in fan stability margins and engine performance. In this way, the design engineer can take into consideration distortion effects on off-design performance, as early as, at the stage of preliminary cycle design.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Ανάπτυξη του λεπτομερούς ομοιώματος των υπόγειων υδάτων του Νομού Ροδόπης

Στο πλαίσιο του παρόντος, περιγράφεται η εφαρμογή του συστήματος προσομοίωσης FEFLOW στις υδρογεωλογικές λεκάνες του Νομού Ροδόπης, με σκοπό την προσομοίωση της κίνησης του υπόγειου νερού στα υδροφόρα στρώματα, της διείσδυσης του θαλασσινού νερού στις παράκτιες περιοχές και της κατανομής των νιτρικών αλάτων στα υπόγεια νερά από τις πιέσεις που ασκούνται κατά τη λίπανση των γεωργικών καλλιεργειώ

Ποσοτική ανάλυση των πιέσεων που ασκούνται από τις αρδεύσεις στα υπόγεια ύδατα του Νομού Ροδόπης: διακύμανση της υπόγειας στάθμης και διείσδυση θαλασσινού νερού

Στο πλαίσιο του παρόντος, ελέγχονται μία σειρά από μέτρα/ενέργειες με σκοπό την ανάλυση και τον μετριασμό των πιέσεων που ασκούνται στα υπόγεια ύδατα του Ν. Ροδόπης από τις αρδεύσεις. Ο έλεγχος των μέτρων γίνεται με το σύστημα προσομοίωσης FEFLOW, στο περιβάλλον του οποίου αναπτύχθηκε το ομοίωμα των υπόγειων υδάτων του Ν. Ροδόπης (βλέπε και Παραδοτέο DB1.9). Τα μέτρα/ενέργειες στοχεύουν στην αντιστροφή της πτώσης της υπόγειας στάθμης και στην υποχώρηση του μετώπου διείσδυσης του θαλασσινού νερού. Η έκθεση αποτελείται από δύο κεφάλαια. Στο πρώτο κεφάλαιο δίνεται η περιγραφή των μέτρων/ενεργειών για την προστασία των υπόγειων υδάτων και στο δεύτερο κεφάλαιο παρουσιάζεται η προσομοίωση των σεναρίων για την εφαρμογή των προτεινόμενων μέτρων αποκατάστασης των υπόγειων υδάτων του Ν. Ροδόπη

Systems analysis approach to the design of efficient water pricing policies under the EU Water Framework Directive

Economic theory suggests that water pricing can contribute to efficient management of water scarcity. The European Union (EU) Water Framework Directive (WFD) is a major legislative effort to introduce the use of economic instruments to encourage efficient water use and achieve environmental management objectives. However, the design and implementation of economic instruments for water management, including water pricing, has emerged as a challenging aspect of WFD implementation. This study demonstrates the use of a systems analysis approach to designing and comparing two economic approaches to efficient management of groundwater and surface water given EU WFD ecological flow requirements. Under the first approach, all wholesale water users in a river basin face the same volumetric price for water. This water price does not vary in space or in time, and surface water and groundwater are priced at the same rate. Under the second approach, surface water is priced using a volumetric price, while groundwater use is controlled through adjustments to the price of energy, which is assumed to control the cost of groundwater pumping. For both pricing policies, optimization is used to identify optimal prices, with the objective of maximizing welfare while reducing human water use in order to meet constraints associated with EU WFD ecological and groundwater sustainability objectives. The systems analysis approach demonstrates the successful integration of economic, hydrologic, and environmental components into an integrated framework for the design and testing of water pricing policies. In comparison to the first pricing policy, the second pricing policy, in which the energy price is used as a surrogate for a groundwater price, shifts a portion of costs imposed by higher water prices from low-value crops to high-value crops and from small urban/domestic locations to larger locations. Because growers of low-value crops will suffer the most from water price increases, the use of energy costs to control groundwater use offers the advantage of reducing this burden.The authors would like to thank the Danish Research School of Water Resources (FIVA) for financial support. Three anonymous reviewers made helpful suggestions that were incorporated into the revised version.Riegels, N.; Pulido-Velazquez, M.; Doulgeris, C.; Sturm, V.; Jensen, R.; Moller, F.; Bauer-Gottwein, P. (2013). Systems analysis approach to the design of efficient water pricing policies under the EU Water Framework Directive. Journal of Water Resources Planning and Management. 139(5):574-582. doi:10.1061/(ASCE)WR.1943-5452.0000284S574582139