A hydrogeological assessment of the Łężkowice brine pumping station near Bochnia (The Carpathian Foothills)

Hydrogeologiczna ocena skutków eksploatacji solanki w Łężkowicach koło Bochni (Pogórze Karpackie)

Summary: In 1991 the Łężkowice brine pumping station closed after 23 years activity, leaving soil and alluvial groundwater heavily contaminated with salt. Piezometry and observations on site suggest that this saline groundwater is discharging directly into the nearby river Raba, an important source of drinking water. By studying trends in chloride concentration and water levels, two possible salt sources were identified on the site. The first is residual salt dissolved from the soil surface and unsaturated zone and carried to the groundwater during recharge events. The second is most active at low groundwater levels and is interpreted as a connection to a source of brine beneath the alluvial cover. Groundwater flow and chloride transport modelling were used to provide a quantitative estimate of saline discharge. Because of the limited availability of model data, many of the parameters used were estimated. In order to validate the model's results, all available data sets were used for calibration. Daily chloride flux measurements made in the Raba river were analysed using a method similar to the baseflow separation of hydrographs in order to give an estimate of groundwater discharge. Short term transient modelling during flood periods was also found to provide a useful calibration and highlighted possible inaccuracies in the initial hydraulic conductivities used. Short term modelling demonstrates that, although the salt supplied to the river by groundwater discharge from the site is only a small percentage of the total load, timing of this discharge is critical. Most of the groundwater discharge occurs at low flow when the river is most vulnerable. When river flows are high and able to accept large quantities of salt, groundwater discharge halts completely. The study concluded that saline groundwater discharge from the site is not a problem at present but may increase in future as the site degrades and underground caverns developed during mining begin to collapse. A ground conductivity survey is suggested as a good method of identifying salt sources should a more detailed study be required.

Słowa kluczowe (w języku angielskim): Wieliczka Foothills, salt deposits, brine, mining, river pollution

Prace Geograficzne, 1998, z. 103, s. 159-178.

Instytut Geografii i Gospodarki Przestrzennej UJ

Pełny tekst (115 KB)