Dimitrios Stathis

Assessment of flood hazard based on natural and anthropogenic factors using analytic hierarchy process (AHP)

Flooding is the most common natural hazard in Greece, and most of low-lying urban centers are flood-prone areas. Assessment of flood hazard zones is a necessity for rational management of watersheds. In this study, the coupling of the analytical hierarchy process and geographical information systems were used, in order to assess flood hazard, based either on natural or on anthropogenic factors. The proposed method was applied on Kassandra Peninsula, in Northern Greece. The morphometric and hydrographic characteristics of the watersheds were calculated. Moreover, the natural flood genesis factors were examined, and subsequently, the anthropogenic interventions within stream beds were recorded. On the basis of the above elements, two flood hazard indexes were defined, separately for natural and anthropogenic factors. According to the results of these indexes, the watersheds of the study area were grouped into hazard classes. At the majority of watersheds, the derived hazard class was medium (according to the classification) due to natural factors and very high due to anthropogenic. The results were found to converge to historical data of flood events revealing the realistic representation of hazard on the relating flood hazard maps.

An Integration of Statistics Temporal Methods to Track the Effect of Drought in a Shallow Mediterranean Lake

During the last decades, a progressive decrease of water level in shallow Mediterranean lakes was recorded. This contribution tried to identify whether the rapid decrease of the Lake Doiran (N. Greece) water level was associated with drought phenomena. Drought characteristics over the study area were revealed by employing the Standardized Precipitation Index (SPI) in different time scales. Negative trends of the SPI drought index were recognized by using the Mann-Kendall non parametric test, which suggested that drought conditions were intensified through time. The impact of the intense drought phenomena to the lake’s water level became evident by employing the Pearson correlation coefficient. A year ahead forecast of future drought conditions was achieved by training a hybrid ARIMA/ANN model. The predicted results indicated that mild drought conditions should be anticipated in the future and the water level would further drop as well.

Estimation of Reference Potential Evapotranspiration with Focus on Vegetation Science—the EmPEst Software

Owing to the difficulties in measuring daily reference potential evapotranspiration, its estimation by means of the ASCE Penman-Monteith approach and various other empirical equations that are less demanding in terms of input data is favoured for various applications in vegetation science and climatology. This study presents the development of a Visual Basic software that can be used for the estimation of the daily PETref by means of the standardized ASCE Penman-Monteith equation for both short (clipped grass) and tall (full-cover alfalfa) crops and thirteen additional empirical equations. Statistical measures of goodness of fit are also calculated to make it easier for users to compare and detect the empirical equations that have the minimum bias of estimation against the ASCE Penman-Monteith equation.

Post-Evaluation of Flood Hazards Induced by Former Artificial Interventions along a Coastal Mediterranean Settlement

AbstractInappropriate artificial activities can escalate the frequency, the intensity, and the magnitude of floods and aggravate their aftermath. Additionally, urban sprawl is responsible for increasing the manifestation of flood events in coastal areas. In this study, the effects of diachronically formulated artificial stream-channel modifications and registered urban expansion on flood hazards were quantified. Initially, land-use changes were monitored over time and a detailed field topographic survey was performed. The peak discharge for a 50-year return period storm event was found to be equal to 42.3  m3/s, as computed by the rational method. A steady flow analysis with a mixed flow regime was then performed so as to compute the water velocity and surface runoff elevation at 49 discrete cross sections for the years of 1945, 1981, and 2009, whereas the inundation extent was found equal to 12,208, 10,519, and 9,530  m2 for the same years by implementing another model. Although the water level and inund...

Μαθήματα δασικής μετεωρολογίας και κλιματολογίας

ΜEΤEΩΡΟΛΟΓΙΑ ΚΑΙ ΚΛΙΜΑΤΟΛΟΓΙΑ [ΑΡΙΣΤΟΤEΛEΙΟ ΠΑΝEΠΙΣΤΗΜΙΟ ΘEΣ/ΝΙΚΗΣ, ΣΧΟΛΗ ΓEΩΠΟΝΙΑΣ, ΔΑΣΟΛΟΓΙΑΣ ΚΑΙ ΦΥΣΙΚΟΥ ΠEΡΙΒΑΛΛΟΝΤΟΣ, ΤΜΗΜΑ ΔΑΣΟΛΟΓΙΑΣ ΚΑΙ ΦΥΣΙΚΟΥ ΠEΡΙΒΑΛΛΟΝΤΟΣ]