### Diploma Thesis defense by Ms. Koulla Vrachnou

"Οptimal prevention design οf salinization using simulation, optimization models and matlab - Field application in area of Troizina in Attica"

Thesis title: Οptimal prevention design οf salinization using simulation, optimization models and matlab - Field application in area of Troizina in Attica

Thursday 28 June 2018, at 14:00 Venue: Hall Κ2. Α3

Examination Committee

• Dr. Emmanouil Varouchakis
• Assistant Professor Nikolaos Paranychianakis

Abstract:

This specific project aims to limit the phenomenon of salinization in the area of municipality Troizina,  that belongs to the Attiki region, which is created due to the pumping of the wells of the area.

Initially, some general groundwater data are reported and the phenomenon of salinization is analyzed. Then, a general reference is made to the methods and numerical models used to simulate groundwater, followed by a more detailed analysis of finite element and finite difference methods. An analysis is made of the PTC model which simulates the groundwater flow in the area for a period of 4 years and the position of the salinization front is calculated based on the existing pumping wells and the actual pumping rates.

Subsequently, a general description of the study area is made and the geographic, geological, hydrological and climatological data of the area are gathered. Afterward, the model of the area is created and the ground water flow is calibrated using hydraulic heights data. The simulation results are used as initial values for optimization scenarios, which are made to improve the salinization condition.

As an initial scenario is the case where all the wells are closed and in each scenario the pumping flow of the wells is disrupted, each separately. The Simplex optimization method is applied through the linprog command in the Matlab program and the response table A, containing the change of hydraulic heights relative to the change of pumping rates, is derived. The process is repeated until the algorithm converges, until the last two results are similar (depending on the convergence criterion set).

In this problem, the algorithm converges at the third step. With these results, in 4 years, the salinization front will be shifted outward, as the figures show. Conclusions and commentary on the results are listed at the end of the project.