Metodologije nalivalnih poizkusov v nezasičenem območju vodonosnika

Klun, Urša (author), Brenčič, Mihael (mentor)

V magistrski nalogi smo obravnavali deset ponikalnih vodnjakov, kjer smo kot testni poligon uporabili območje objekta LTH Trate, ki se nahaja vzhodno od Škofje Loke na Sorškem polju. Izvedli smo deset nalivalnih poizkusov po metodi Hvorsleva in dva stopenjska nalivalna poizkusa za testiranje nezasičenega območja vodonosnika. Pri nalivalnih poizkusih po Hvorslevu smo analizirali standardizirane višine dviga in znižanja, kot tudi logaritmirane višine znižanja za izračun koeficienta prepustnosti po Hvorslevu. Najmanjši izračunan koeficient prepustnosti je 1,9*10-7 m/s, največji koeficient prepustnosti pa 1,6*10-5 m/s. Izvedli smo dva ločena stopenjska nalivalna poizkusa. Pri prvem izvajanju smo imeli težavo s padanjem tlaka v hidrantnem omrežju in z merjenjem pretoka. Pri drugem stopenjskem nalivalnem poizkusu smo začeli poizkuse z nizkim pretokom, ki smo ga vsako naslednje nalivanje povečali. Pretoke smo merili z vodovodno uro. Vodo smo nalivali v vodnjak do navidezne stabilizacije, ki smo jo ohranjali določen čas, za tem smo prenehali z nalivanjem in pustili, da gladina vode v vodnjaku pade. Stabilizirane višine naraščajo linearno, z izhodiščem pri neki določeni višini, saj je potreben začetni tlak za generacijo toka vode. Za analize smo uporabili krivuljo dviga in stabilizacije, čez katero smo z nelinearno korelacijo izračunali prilagajočo logistično krivuljo. Izhajali smo iz logistične enačbe in izračunali hitrost in pretok dviga vode v vodnjaku med nalivanjem ter pretok ponikanja. Opazili smo razlike med krivuljami v začetnem delu nalivanja. Iz pretokov infiltracije smo izračunali volumen poniknjene vode, ki smo ga primerjali z izračunanim volumnom sintetičnega hidrograma ekstremnih padavin s povratno dobo dveh let najbližje merilne postaje (Letališče Jožeta Pučnika Ljubljana). S pomočjo ogrinjače na podatke sintetičnega hidrograma smo izračunali pretok ponikanja, iz katerega smo s pomočjo grafa stabiliziranih višin razbrali višino dviga vode pri izračunanem pretoku, kar nam pomaga pri dimenzioniranju ponikovalnega vodnjaka.

• Language: Slovenian
• Keywords: nalivalni poizkusi, nezasičeno območje, dimenzioniranje vodnjaka, hidrogeologija, Trata pri Škofji Loki
• Work type: Master's thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-114371
• COBISS.SI-ID: 1552222
• Publication date in RUL: 24.02.2020

Secondary language

• Language: English
• Title: Methodology of infiltration tests in unsaturated areas of aquifer

Abstract

The Master's thesis presents reviews of ten wells on the premises of LTH Trata, which is located east of Škofja Loka on the Sorško polje fields. We have conducted ten infiltration tests using the Hvorslev method and two step infiltration tests for testing the unsaturated zone of the aquifer. With the infiltration tests by Hvorslev we have analyzed the graph curve of water level fall in the well. The minimum calculated permeability coefficient is 1,9*10-7 m/s, and the maximum 1,6*10-5 m/s. We have conducted two separate step infiltration tests. During the first test, we faced the issue of lowering pressure in the hydrant network and with measuring the water flux. We have started our second attempt with a low water flux, which we have increased with each consecutive infiltration test. We measured the flow with a discharge meter. We poured water inside the well until seeming stabilization, which was preserved for some time, after which we have ceased adding water and observed water level falling inside the well. Stabilized water levels rise linearly with a starting point at a specific height, since starting pressure is required to generate water flux. For analysis we have used a graph curve of rise and stabilization, for a logistic curve was calculated by nonlinear correlation and applied. Based on the logistic equation we calculated the velocity and discharge of water level rise during the inflow, giving us also the infiltration flow rate. We noticed a difference in graph curves at the starting phase of inflow. We calculated the volume of the outflow from the infiltration fluxes, which was compared to the calculated volume of a two-year period of extreme precipitation from the synthetic hydrograph at the closest precipitation station (Airport Jože Pučnik Ljubljana). Analyzing the tangent from the acquired synthetic hydrograph data, we were able to calculate the flux. Using the stabilized levels chart we then concluded the height of water rise for our calculated flux. The resulting information enabled us to determine the dimension of the infiltration well.

• Keywords: infiltration tests, unsaturated zone, well design, hydrogeology, Trata pri Škofji Loki