Identification of minimum ground water levels of the Samobor-Zaprešić Aquifer : master’s thesis

Predmet istraživanja ovog rada je samoborsko-zaprešićki otvoreni vodonosnik koji je građen od aluvijalnih kvartarnih naslaga međuzrnske poroznosti izrazito visoke hidrauličke vodljivosti. Na području ovog vodonosnika postoji višegodišnji kontinuirani negativan trend razina podzemne vode, pri čemu u sušnim razdobljima, razina podzemne vode pada ispod kote gornjeg ruba filtra pojedinih zdenaca na vodocrpilištima Bregana, Strmec i Šibice. Analizom podataka o povijesnim razinama podzemne vode u razdoblju od 6. 8. 1981. godine do 1. 10. 2015. godine na području vodocrpilišta Bregana i Strmec i u razdoblju od 1. 3. 1982. godine do 1. 10. 2015. godine na području vodocrpilišta Šibice, kreirani su nivogrami zdencima referentnih piezometara koji su uspoređivani s kotama gornjeg ruba filtara u zdencima. Analizom su identificirani zdenac i vrijeme u kojem u istraživanom razdoblju razina podzemne vode u periodu recesije najprije dosegne kotu gornjeg ruba filtra, stoga su minimalne razine podzemne vode samoborsko-zaprešićkog vodonosnika identificirane sukladno koti gornjeg ruba filtra zdenca B1 na vodocrpilištu Bregana koja iznosi 129,5 m n. m., a postignute su 5. 8. 1992. godine. Kao krajnji rezultat prikazana je karta ekvipotencijala koja prikazuje stanje razina podzemne vode samoborsko-zaprešićkog vodonosnika na dan 5. 8. 1992. godine.Abstract: The subject of research of this thesis is the Samobor-Zaprešić unconfined aquifer, which is made of alluvial quaternary sediments that are characterized by intergranular porosity and significantly high values of hydraulic conductivity. Aquifer's area is characterized by continuous multiannual negative trend of ground water levels, which combined with dry recession periods causes decrease of the ground water levels below top screen elevation in particular pumping wells at well fields Bregana, Strmec and Šibice. The analysis of historical ground water levels data in the period from 6th August 1981 to 1st October 2015 in the area of Bregana and Strmec well fields and in the period from 1st March 1982 to 1st October 2015 in the area of the Šibice well field, resulted in creation of ground water hydrographs of referent observation wells. They were compared to top screen elevations. The analysis identified time point and the pumping well in which, during recession periods, the water table first reaches the top screen elevation. Minimum ground water levels of Samobor-Zaprešić aquifer were determined according to top screen elevation at the B1pumping well at the Bregana well field, with value of 129.5 meters above sea level and it was first reached on the 5th August 1992. A map that shows the condition of groundwater levels determined on the 5th August 1992 at the Samobor-Zaprešić aquifer area was created as the final result of the analysis