Thesis Title: Spatio-temporal evolution off drought events in the island of Crete, using SPEI and SPI

Thursday 11 October 2018, at:14:00, Venue: Hall Κ2. Α11

Examination Committee

• Assistant Professor Nikolaos Paranychianakis (advisor)
• Dr. Emmanouil Varouchakis
• Professor Nikolaos Nikolaidis

Abstract:

Droughts constitute, arguably, a complicated phenomenon that depends on a wide range of factors and appeared in the last decades very intensely and globally. It is related to many dramatic effects in many fields and especially in the field of agriculture. The Mediterranean countries face drought events very often and they could be called as the most drought-vulnerable areas, in the matter of  future extreme rainfall events, due to the  transitional zone that own, between North Africa and South Europe. For these reasons, the interest of deeper understanding drought events, the decrease of potential dangers that may be occured as well as the adaptation of people in future potential events, are undoubtedly some of the most critical issues that concern the scientific society. Additionally, the combination of heatwaves and droughts could intensify the severity of impacts. In an effort to monitor and identify a drought event, we emphasize in the use of drought indices. Drought indices could be estimated based on more than one meteorological  variables. In the present study, we examine the respond of SPEI and SPI indices to the variability of drought events that have occurred in 8 areas of Crete in 2006-2017 period. For the calculation of drought indices, we used monthly rainfall and temperature data for the aforementioned period. The climate variability figures conducted with the use of statistical ‘R’ SPEI package, for 1, 3, 12-month timescales in the regions of Chania, Palaiochora, Heraklion, Moires, Agios Nikolaos, Rethimnon, Ierapetra and Siteia. According to the data, the figures of the average of rainfall and temperature  for each region during the period of 2011-2017, were carried out for the purpose of better understanding of dry and wet periods. The results of the timescales depict similarities and also differences in the way that SPI and SPEI react under special circumstances. SPI consistent with the SPEI considerably, without significant differences between them and can be appropriate for the estimation of the drought’s characteristics. The advantage of SPEI to respond in the temperature variability in different regions and to note the important role of evapotranspiration, make it more representative under climate conditions in which high variability of temperature dominates. Generally, in accordance with the results, last years, there is an increased trend in the frequency of drought events, which is very alarming as regards the expected deficit of available water resources (storages of surface water and ground water). It is critical for all drought-prone nations to take steps in decision-making process in drought risk management, to reduce vulnerability to agricultural drought and generally, to enhance the resiliance of the ecosystems in terms of the new climatic conditions.