Diploma Thesis Defense by Mr. Leonidas Koutselis
Thesis Title: «Geostatistical Analysis of groundwater level data at the Water District of Crete»
Friday 20 February 2020, at: 11:00, Venue: Hall Κ2.Α3
- Professor George Karatzas (advisor)
- Associate Professor Nikolaos Paranychianakis
- Dr. Emmanuel Varouhakis
Fresh water is a vital factor in the existence of life on our planet. The fact that it is not abundant leads to the necessity of finding ways to manage it rationally. In this context, this thesis is aiming at identifying the aquifers of Crete that are in poor quantitative condition, in order to take the necessary measures to address the problem.
For this purpose, we applied geostatistical analysis of average groundwater level observations taken from 472 locations at the island of Crete and of average annual rainfall that was recorded at 81 meteorological stations. Then, the correlation between them was explored. Geostatistical analysis helps in estimating physical quantities at points in a study area where there are no measurements by using observations at neighbouring points. The most popular geostatistical methods are the Kriging techniques.
In this work the ArcGIS program was applied in terms of Ordinary Kriging method using four different variogram models (spherical, exponential, Gaussian, K-Bessel/Matern) to determine the spatial variability of the average aquifer level and the average rainfall. Estimation errors and uncertainty of these models were examined in order to compare them and select the optimal one. Maps of estimated average level and estimated average rainfall throughout the island were produced and discussed. Significant areas of the island with maximum average groundwater level below 30 m and less than 600 mm of rainfall per year were identified. These aquifers were assessed for poor quantitative condition.
Αn evaluation of results was performed as well as an assessment of the impact of the errors. Propositions for future research and for measures to address the degradation of the aquifers of Crete were presented.