eprintid: 711 rev_number: 9 eprint_status: archive userid: 17 dir: disk0/00/00/07/11 datestamp: 2017-08-15 21:49:38 lastmod: 2017-08-15 21:49:38 status_changed: 2017-08-15 21:49:38 type: report metadata_visibility: show creators_name: Benham, Graham creators_name: Frolkovič, Peter creators_name: Ivanov, Tihomir creators_name: Mondal, Raka creators_name: Mondal, Sourav creators_name: Rottschäfer, Vivi creators_name: Kaouri, Katerina creators_name: Papageorgiou, Demetrios creators_name: Nikolopoulos, C. creators_name: Ockendon, H. creators_name: Christodoulides, Paul creators_name: Riseth, Asbjørn Nilsen creators_name: Lacey, A.A. creators_id: creators_id: creators_id: creators_id: creators_id: creators_id: creators_id: kaouri@maths.ox.ac.uk creators_id: creators_id: creators_id: creators_id: creators_id: creators_id: corp_creators: Natasa Neokleous title: Mathematical modelling of the Germasogeia aquifer ispublished: pub subjects: Fluids studygroups: esgi125 companyname: Water Development Department, Cyprus full_text_status: public abstract: Two challenges related to improving the management of the Germasogeia aquifer were presented to the Study Group by the Cyprus Water Development Department (WDD), the public organisation responsible for managing the wa- ter resources in Cyprus. The rst challenge was how to optimally recharge the aquifer in order to compensate for the extraction of drinking and irrigation water whilst preventing sea water intrusion. In order to address this challenge we developed model for the water in the aquifer. Note that by exploiting the long, thin nature of the aquifer we only develop two-dimensional models in this work. We rst develop a simple model based on Darcy ows for porous media which gives the water table height for given dam seepage rate, recharge and extraction rates; we neglect seawater intrusion. We then use the steady version of this model to develop an optimized recharge strategy with which we can identify minimal recharge required for a desired extracted water volume such that the minimum prescribed water table is respected. We explore 4 di erent scenarios and we nd that in certain cases there can be a considerable reduction in the amount of recharged water compared to the current empirical strategy the Water Development Department is employing, where water is recharged and extracted in equal proportions. To incorporate the e ects of seawater intrusion, which can be very damaging to the water quality, we next develop transient two- dimensional models of saturated-unsaturated groundwater ow and solve them numerically using the open source software SUTRASuite and the commercial package ANSYS FLUENT; the position of the water table and the seawater- freshwater interface are determined for various extraction/recharge strategies. Data from the WDD are used in some of the simulations. The second important challenge we were asked to look at was to predict the transport of pollutants in the aquifer in the case of an accidental leakage. An advection-difusion equation for the contaminant concentration is introduced and simulations are under- taken using the commercial package COMSOL. The concentration pro les of the contaminant are studied and we nd that the e ect of contamination varies depending on where the contamination site is; the closer the contamination site is to the dam, the larger the extent of contamination will be. problem_statement: The main aims of the WDD for e ectively managing the Germasogeia aquifer are: a) supply drinking water of acceptable quality to the greater area of Limassol b) protect the Germasogeia aquifer from seawater intrusion, and c) minimise groundwater losses to the sea. In this connection, we were presented with the following two challenges for the Study Group week: 1. How can the e ectiveness of the recharge process be maximised? At the moment there are four recharge points where water is inserted into the aquifer and 19 boreholes that pump water out. What is the optimal recharge protocol, i.e. for how long and at which locations should we recharge the aquifer while simultaneously (a) protecting the aquifer from seawater intrusion, and (b) minimising water losses to the sea? 2. If there is contamination by sewage or other pollutants, where will the pollution spread and how fast? What would this mean for the quality of the extracted water? Which measures should WDD take in order to minimise the contamination e ects? date: 2017-07-31 date_type: completed related_url_url: https://www.esgi-cy.org/problems/ citation: Benham, Graham and Frolkovič, Peter and Ivanov, Tihomir and Mondal, Raka and Mondal, Sourav and Rottschäfer, Vivi and Kaouri, Katerina and Papageorgiou, Demetrios and Nikolopoulos, C. and Ockendon, H. and Christodoulides, Paul and Riseth, Asbjørn Nilsen and Lacey, A.A. (2017) Mathematical modelling of the Germasogeia aquifer. [Study Group Report] document_url: http://miis.maths.ox.ac.uk/miis/711/1/ESGI125-aquifer-v2-1.pdf