Ecological Approach on Investigating the Open Pit Lakes Developed in Oltenia Mining Region: A Case Study of Urdari Lake, Romania

This study aims to present some ecological aspects regarding these lakes, and, as case study, we chose the lake formed in the remaining gap of Urdari open-pit (within the Rovinari Mining Basin). Artificial lakes, resulting either from damming watercourses or by flooding of gaps resulting from excavations are often found all over the world.

Formation of so-called open-pit lakes has become an increasingly common practice in Romania (more precisely in the Oltenia Mining Basin, where the lignite deposit contained in Dacian and Romanian formations was and is extracted through open-pits). The flooding process of the remaining gaps is in general a natural one, as water comes from underground sources (phreatic and pressurized aquifers) and from precipitations (including runoff waters from the surrounding terrains). This practice is considered to be a type of ecological reconstruction of former exploitation areas and has been applied worldwide for quite a time (in Germany, Poland, Czech Republic, Spain, USA, Australia, etc.). The modifications of the physical and chemical properties of the biotope are the consequence of the activity of the biocenoses. There is an interdependence between the biotope and the biocenosis, the interrelationships are close and the influences are mutual. However, the authors consider that given the multitude of similar conditions (bioclimate, geology, topography, etc.) in which they form, the preliminary conclusions of this study can be extrapolated for other lakes in the area (existing, such South Pesteana and Moi, or planned, such as Rosia and North Pesteana). This study presents data on the existing biotope and biocenoses (restricted to species identification), without going into specific details about populations, ecosystem production, energy and matter flows within it, as these investigations demand a longer period of time and more resources and are foreseen for a future development stage of this study. We recommend continuous monitoring of the vegetation in the studied area, in order to complete the inventory with phytocoenoses whose emergence is related to natural multi-annual dynamics as well as human interventions.