Estimating Water Retention in Post-mining Excavations Using LiDAR ALS Data for the Strzelin Quarry, in Lower Silesia

Abstract

A digital terrain model of the Strzelin granite quarry was created from ISOK project data obtained from airborne laser scanning (ALS). Based on 2009, 2012, and 2014 data, the volume of water in the Strzelin quarry's two excavations were determined. Additionally, the predicted volume of retained water after mining ceases was calculated, assuming a water level of 150.0 m a.s.l. In 2014, the two reservoirs retained, respectively, ≈ 0.14 and 0.01 million m 3 of water. If the two pits are eventually connected, ≈ 6.6 million m 3 of water could be retained. Including the 2014 water volume as a small-scale retention basin would increase the volume of retained water in the Ślęza catchment and Strzelin County by 19.0%, and 34.2%, respectively. The hypothetical reservoir created after mining ends would increase small-scale (reservoir and pond) retention ≈ 8 times in the Ślęza catchment and ≈ 15 times in the County, constituting a significant improvement.

The Use of Digital Terrain Models to Estimate the Pace of Filling the Pit of a Central European Granite Quarry with Water

“…In many countries (e.g., in Australia, Canada, China, Czech Republic, Germany, Italy, France, Poland, Sweden, the U.K. and the USA), hundreds of new pit or quarry lakes have been created [3,12,13,16,19,20,23,[27][28][29][30][31][32][33][34][35][36][37] in former excavations of clay, sand and gravel, in former stone quarries, and in former open-cast coal and lignite mines when their respective operations ceased [10,15,23,36,[38][39][40][41]. Pit lakes or quarry lakes may be used for various purposes, including, among others: recreation and tourism [3,5,[9][10][11][12]16,17,21,26,[42][43][44], wildlife habitats [5,[9][10][11][12]16,24], aquaculture and fish farming [3,…”

“…The potential use of water from pit lakes or quarry lakes depends on its quality and amount [11,19,23,36,37,47,[54][55][56][57]. These values are influenced by the size of the excavation pit, hydrogeological conditions, the geological structure of the mine and its surroundings, as well as the size and management of its own (direct) catchment [3,23,25,36,37,40,44,54,[58][59][60][61].…”

“…After discontinuation of dewatering, the pits fill with groundwater, rainfall, and surface runoff to form emerging pit lakes or quarry lakes [3,23,24,27,31,32,37,41,42,62,63], which may have different depths [3,23,24,30,31,36,50,57,58,61,[64][65][66][67], surface area [3,23,24,32,36,37,50,57,58,66,67] and cubic capacities [23,36,50,67,68], depending on the type of the excavated material and mining technology used [23,30,36,37,56,61,65]. Depending on the geomorphological parameters of an open-excavation pit, hydrogeological conditions, the geological structure of the mine and its surroundi...…”

“…The monitoring of mining and post-mining areas may be carried out with use of LiDAR and GIS technology [23,72,73]. The geomorphological parameters of the pit (in particular the cubic capacity of excavation) indicate the potential amount of water required to fill the excavation pit, which will become the bowl of the new pit lake or quarry lake.…”

“…The geomorphological parameters of the pit (including its cubic capacity, surface area and depth) may be determined with the use of traditional geodetic methods (levelling) or modern ones, such as GNSS technology and the RTK method [74,75]. If LiDAR data are available or may be obtained, the geomorphological parameters may be determined based on data from terrestrial laser scanning (TLS), airborne laser scanning (ALS), mobile laser scanning (MLS) techniques, or other photogrammetric measurements (e.g., with use of unmanned aerial vehicles (UAVs)) [23,[75][76][77][78][79][80][81]. These methods can also be used to determine the parameters of their own catchments (direct catchments of the pit) that are necessary for hydrological calculations.…”