Δεμερτζή, Κλεονίκη

Preferred name

Δεμερτζή, Κλεονίκη

Translated Name

Demertzi, Kleoniki

Alternative Name

Demertzi, Κ.

Job Title

Μέλος Τομέα Διαχείρισης Υδατικών Πόρων και Κλιματικής Αλλαγής

Main Affiliation

ORCID

0000-0003-4842-1974

Now showing 1 - 5 of 5

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Assessing Annual Actual Evapotranspiration Based on Climate, Topography and Soil in Natural and Agricultural Ecosystems
(2021)
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Pisinaras, Vassilios
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Lekakis, Emanuel
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Tziritis, Evangelos
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Babakos, Konstantinos
Simple formulas for estimating annual actual evapotranspiration (AET) based on annual climate data are widely used in large scale applications. Such formulas do not have distinct compartments related to topography, soil and irrigation, and for this reason may be limited in basins with high slopes, where runoff is the dominant water balance component, and in basins where irrigated agriculture is dominant. Thus, a simplistic method for assessing AET in both natural ecosystems and agricultural systems considering the aforementioned elements is proposed in this study. The method solves AET through water balance based on a set of formulas that estimate runoff and percolation. These formulas are calibrated by the results of the deterministic hydrological model GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) for a reference surface. The proposed methodology is applied to the country of Greece and compared with the widely used climate-based methods of Oldekop, Coutagne and Turk. The results show that the proposed methodology agrees very well with the method of Turk for the lowland regions but presents significant differences in places where runoff is expected to be very high (sloppy areas and areas of high rainfall, especially during December–February), suggesting that the proposed method performs better due to its runoff compartment. The method can also be applied in a single application considering irrigation only for the irrigated lands to more accurately estimate AET in basins with a high percentage of irrigated agriculture.
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Assessing the Robustness of Pan Evaporation Models for Estimating Reference Crop Evapotranspiration during Recalibration at Local Conditions
(2020)
Babakos, Konstantinos
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Papamichail, Dimitris
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Tziachris, Panagiotis
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Pisinaras, Vassilios
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A classic method for assessing the reference crop evapotranspiration (ETo) is the pan evaporation (Epan) method that uses Epan measurements and pan coefficient (kp) models, which can be functions of relative humidity (RH), wind speed (u2), and temperature (T). The aim of this study is to present a methodology for evaluating the robustness of regression coefficients associated to climate parameters (RH, u2, and T) in pan method models during recalibration at local conditions. Two years of daily data from April to October (warm season) of meteorological parameters, Epan measurements from class A pan evaporimeter and ETo estimated by ASCE-standardized method for the climatic conditions of Thessaloniki (Greece, semi-arid environment), were used. The regression coefficients of six general nonlinear (NLR) regression Epan models were analyzed through recalibation using a technique called "random cross-validation nonlinear regression RCV-NLR" that produced 1000 random splits of the initial dataset into calibration and validation sets using a constant proportion (70% and 30%, respectively). The variance of the regression coefficients was analyzed based on the 95% interval of the highest posterior density distribution. NLR models that included coefficients with a 95% HPD interval that fluctuates in both positive and negative values were considered nonrobust. The machine-learning technique of random forests (RF) was also used to build a RF model that includes Epan, u2, RH, and T parameters. This model was used as a benchmark for evaluating the predictive accuracy of NLR models but, also, for assessing the relative importance of the predictor climate variables if they were all included in one NLR model. The findings of this study indicated that locally calibrated NLR functions that use only the Epan parameter presented better results, while the inclusion of additional climate parameters was redundant and led to underfitting.
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A Simplistic Approach for Assessing Hydroclimatic Vulnerability of Lakes and Reservoirs with Regulated Superficial Outflow
(2019)
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Aschonitis, V.
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Papamichail, D.
This study proposes a simplistic model for assessing the hydroclimatic vulnerability of lakes/reservoirs (LRs) that preserve their steady-state conditions based on regulated superficial discharge (Qd) out of the LR drainage basin. The model is a modification of the Bracht-Flyr et al. method that was initially proposed for natural lakes in closed basins with no superficial discharge outside the basin (Qd = 0) and under water-limited environmental conditions {mean annual ratio of potential/reference evapotranspiration (ETo) versus rainfall (P) greater than 1}. In the proposed modified approach, an additional Qd function is included. The modified model is applied using as a case study the Oreastiada Lake, which is located inside the Kastoria basin in Greece. Six years of observed data of P, ETo, Qd, and lake topography were used to calibrate the modified model based on the current conditions. The calibrated model was also used to assess the future lake conditions based on the future climatic projections (mean conditions of 2061-2080) derived by 19 general circulation models (GCMs) for three cases of climate change (three cases of Representative Concentration Pathways: RCP2.6, RCP4.5 and RCP8.5). The modified method can be used as a diagnostic tool in water-limited environments for analyzing the superficial discharge changes of LRs under di erent climatic conditions and to support the design of new management strategies for mitigating the impact of climate change on (a) flooding conditions, (b) hydroelectric production, (c) irrigation/industrial/domestic use and (d) minimum ecological flows to downstream rivers. Hydrology 6(3), 61. https://doi.org/10.3390/hydrology6030061
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Assessing Lake Response to Extreme Climate Change Using the Coupled MIKE SHE/MIKE 11 Model: Case Study of Lake Zazari in Greece
(2022)
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Papamichail, D.
Lakes, either artificial or natural, are greatly important as a component in their catchments’ hydrology, but also as ecosystem service providers. However, due to climate change, they have begun to face numerous problems with their water quality and quantity. Furthermore, general circulation models (GCMs) show future climate change with a reduction in rainfall and increase in temperature. The aim of the current study is to present an application where GCMs and state-of-the-art hydrological modelling system MIKE SHE/MIKE 11 are combined for assessing the response of a Greek lake in terms of its water balance and water level under climate change. Four general circulation models (GCMs; GFDL-CM3, MIROC-ESM-CHEM, MIROC-ESM, IPSL-CM5A-LR) for the extreme climate change scenario of RCP8.5 were used in the basin of Lake Zazari in Greece as a case study. Results showed that, by keeping the irrigated demands (the main water user) unchanged in the future, the lake exhibited a lower water level for all GCMs, fluctuating from −0.70 to −1.8 m for the mean (min)water level and from −0.30 to −1.20 m for the mean (max) water level. Instead of the above and by preserving the amount of withdraw water n from the lake at a certain percentage of inflows, the irrigated area should be reduced from 54.1% to 64.05% depending on the circulation model.
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Assessing lake vulnerability to climate change using the coupled MIKE SHE/MIKE 11 model: Case study of Lake Zazari in Greece. Paper presented at 11th World Congress on Water Resources and Environment (EWRA 2019) “Managing Water Resources for a Sustainable Future”. Madrid, Spain, 25-29 June 2019
(2019)
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D. Papamichail
If the worst predictions of general circulation models (GCMs) about climate change become true, then lakes will hardly manage to maintain their current conditions (Zhang et al. 2016) especially in regions, which have been identified as climate change hot spots such as the countries of Mediterranean Basin (Loizidou et al. 2016) from which Greece is of special interest since it has 54 lakes/reservoirs of 0.5 km2 minimum size. The hydrological models are important tools for assessing the water balance components of lakes and for supporting the design of water management strategies. Depending on the modelling purposes and the specific attributes of a lake, different types of models and different levels of model complexities can be selected, starting from complex models such as MIKE SHE (Abbott et al. 1986), WATLAC (Zhang 2011) or using simpler methods (Yang et al. 2018). The MIKE model is among the most integrated models and has been used in the past for similar cases (Singh et al. 2010), while in combination with the future climate projections of general circulation models (GCMs), can be used to investigate lake conditions under future climate scenarios. The aim of this study is to present an application for analyzing the vulnerability of a lake to climate change using the MIKE SHE/11 model using as a case study the Lake Zazari in Greece.

Δεμερτζή, Κλεονίκη

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