aerial drone view of flooded sand pit. an artificial lake after a flooded sand pit. forest submerged in a lake. sunken sandpit

sandmine sandpit mining damage olkusz lake forest klucze flooded water submerged pomorzany sunken clear district hole pit swallow closure poland area landscape nature environment excavation terrain marsh reservoir quarry depth limestone ecosystem refilling surface aquatic reflection greenery ripples submersion scenic tranquil serene geology topography vegetation habitat reclamation wetlands