Sand and gravel mining impact on the surface water quality: a case study from the city of Tirebolu (Giresun Province, NE Turkey)

The water resources in Turkey are under immense pressure due to various kinds of anthropogenic activities among which sand and gravel mining is the most disastrous one due to its adverse environmental impacts. In this study, impacts of the sand and gravel mining activities in the city of Tirebolu, Giresun Province, on the water quality of the stream Harşit, which courses in the Eastern Black Sea Basin of Turkey, are investigated in terms of ten water quality indicators, namely turbidity (T), electrical conductivity (EC), dissolved oxygen (DO), pH, suspended sediment concentration (SSC), water hardness (WH), aluminum ion (Al3+), manganese ion (Mn2+), total chromium and total iron. Based on the average annual values of the studied water-quality indicators, it was concluded that the stream water quality was not impacted with regard to EC, DO, pH, WH, and Al3+ despite the seventeen sand and gravel pits operated in the stream Harşit. Due to the fact that sand and gravel mining has used the stream Harşit surface water for material washing, an increase of 125 % in T, 134 % in SSC, 63 % in Mn2+, 98 % in total chromium, and 111 % in total iron has been determined, respectively, and so the stream water quality has been deteriorated. It is thought that this deterioration may affect the groundwater quality of the stream Harşit aquifer from there a groundwater of two-and-a-half million cubic meters per year of which has been drawn for domestic water demand of the people in the city of Tirebolu.