Student: “Alexios Kostakis”
Program: “Data Science and Information Technologies”
Title: “Study of spatiotemporal changes within the abandoned flotation plant site of Kirki (NE Greece) via clustering on Sentinel-2”
Abstract:
The abandoned flotation plant at Kirki, northeastern Greece, represents one of the most prominent unmanaged mining legacies in the eastern Mediterranean. Since operations ceased in 1997, seven tailing ponds have remained exposed to atmospheric weathering, generating persistent acid mine drainage and mobilizing heavy metals into the surrounding drainage network. This thesis applies spatio-temporal remote sensing to characterize contamination patterns across the Kirki tailings complex between 2015 and 2022. Multiple cloud-free Sentinel-2 acquisitions were processed to extract per-pixel reflectance time series from 458 active pixels distributed across seven tailing ponds and three near-pond zones, comparing each pixel’s spectral signature against a library of mineral endmembers using Pearson correlation. The temporal evolution of mineral assemblages was analyzed through K-means clustering, hierarchical clustering with Ward’s linkage, and the Hungarian algorithm for cross-date cluster matching. Four geochemically distinct clusters emerge consistently across the observation period, mapping to discrete mineralogical regimes ranging from dynamic butlerite-dominated transition zones to stable jarosite-dominated cores. A central finding is that spectral contamination signatures do not respect physical pond boundaries, with near-pond peripheral regions expressing contamination footprints comparable to or greater than any individual pond. Precipitation emerges as the dominant environmental control, with cumulative rainfall triggering anomalous mineral dissolution and cluster reorganization across the site.
Date/Time: 30/3/2026 – 2:00PM
Examination Committee:
Dr. Konstantinos Koutroumbas
Assoc. Prof.  Aggelos Pikrakis
Dr. Olga Sykioti

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