Saline gravel pit lakes in Italy

What is it about?

If gravel is excavated in areas where the water table is close to the surface, new lakes form in the gravel pits. These lake change the landscape but also the hydrology and hydrochemistry of a watershed or drainage basin. The gravel pit lakes of this study were excavated in the coastal zone near Ravenna (Italy) where the groundwater is only fresh at the very top of the aquifer and for the rest consists of old (Holocene) and new seawater and is brackish to saline. One of the effects of the gravel pit lakes is that rain falling on top of the lakes mixes immediately with brackish water and so is lost for any use. Another affect of the gravel pit lakes is the fact that more water evaporates from the basin, especially in the Mediterranean Summers. Another effect yet is that groundwater rich in dissolved minerals but also containing potentially toxic elements such as Arsenic and barium flows into the gravel pit lakes. Because the lake water is different from the groundwater, chemical reactions occur and certain minerals (for example Iron hydroxides and Calcite) precipitate on the lake bottom. This paper includes furthermore detailed calculations of the water budget of the Italian gravel pit lakes considering the amount of groundwater flowing in and out of the lakes, changes in climate and consequences for the salinity of the gravel pit lake water. Gravel pit lakes offer the possibility for many different uses including recreation (fishing, boating) and storage of energy, water and more but they need to be monitored.

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