22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Analysis of hydrographs from a karst aquifer in a former mining area, Hungary

23 Sep 2019, 16:00
1h
Trade Fairs and Congress Center (FYCMA)

Trade Fairs and Congress Center (FYCMA)

Av. de José Ortega y Gasset, 201 29006 Malaga, Spain
Poster Topic 5.3 - Advanced modelling tools for subsurface hydrology: from the vadose zone to deep environments Poster with refreshments

Speaker

Kamilla Modrovits (Department of Geology, Eötvös Loránd University, Budapest, Hungary)

Description

The Transdanubian Range is a complex, thick karst aquifer, which can be characterized by hydraulic interrelationships. Because of mining, a large amount of groundwater was extracted from this area in the second part of the 20th century for a preventive purpose. At the end of the 90's, the mining was stopped, and the rising of karst water has begun, which led to serious economic and technical-engineering problems as well. The examination of hydrographs of observation wells, showing the recovery process, helps to understand the hydraulic behaviour of the karst aquifer and to prepare for problems related to the phenomenon.
The aim was to understand this special hydrogeological situation by applying stochastic approaches. 127 long-term time series could be analysed from the area of the depression having affected by water recovery. The time series (from 1995 to 2015) located in the study area have been grouped into three clusters with hierarchical cluster analysis based on their pattern. The individual groups were separated prior to their spatial positions related to the depression centre. The water levels of the first group showed significant (30-40 meters) and continuous rising. The water levels in these wells are characterized by less fluctuation and the effect of the recovery is crucial. These wells are located in the NE part of the study area. In the wells of the second group the water levels increased tens of meters as well, moreover, a definite fluctuation pattern has also occurred. These wells are located in the area represented by high water level of topographic heights. The wells of the third group are situated in the SW part of the study area where the rising of the water level is also typically tens of meters (some places more than 70 meters) but without a fluctuation pattern. As a next step, the forecast of the water levels in each individual well took place with the estimation of a well-fitting trend and their extrapolation until January 2030. Thus, the so-called growth curves, which has an upper limit, have been fitted to the time series describing appropriately the recovery process. A significant part (82.68%) of the studied hydrographs showed an excellent fitting (where R$^{2}$>0.9). In most cases, out of the 10 examined functions, the process can be modelled most accurately by the so called "Richards" and "63%" functions. Important result of the research is, that using the growth curve models can expand the number of methods which may be used in forecasting groundwater levels.
This research is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 810980.

Primary authors

Kamilla Modrovits (Department of Geology, Eötvös Loránd University, Budapest, Hungary) József Kovács (Department of Geology, Eötvös Loránd University, Budapest, Hungary)

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