Türkiye Jeoloji Bülteni

Effects of Urban Activities on Coastal Aquifers: Case Study in the Eastern Black Sea Basin

Abstract: The Eastern Black Sea Basin is the highest rainfall area in Turkey with an average rainfall of 1300mm. However, this region is one of the poorest regions in terms of spring and groundwater potential due to itstopography having extremely high slopes, and impermeable-less permeable rocks exposed in the basin. Alluvium,which is carried by streams flowing from north to south along the Eastern Black Sea coastline, are important interms of groundwater. Alluvium, of which thickness and width decrease from north to south, has a length of 1-16 kmand a width of 50-1500 m. Water is provided from wells that are drilled in alluvium with a thickness of up to 40 m.According to DSI (2015) data, the static water level is between 0.3 and 1 m, while the dynamic water level is between5 and 15 m. The volume of water stored in the coastal aquifers of the Eastern Black Sea Basin is 238 hm3. Some of these aquifers are still used and some were used in the past as drinking water sources. However, in recent years,construction such as industrial sites, quarries, coal storage and packaging facilities, warehouses and buildings ofsome public institutions and organizations has been increasing on these aquifers, which form partially flat areasbetween narrow valleys. This construction adversely affects both the quantity and quality of shallow groundwaterstored in alluvium. The aquifers are the most important groundwater sources in the basin and are used to supplydrinking and potable water for 4 cities. Değirmendere and Taşlıdere aquifers, which provided drinking-potablewater in the past, were completely under stress by urbanization and the use of groundwater was terminated. Theurban activities on Melet, Civil, Pazarsuyu (Ordu) and Batlama and Keşap (Giresun) aquifers, which are locatedin the settlement area, continue to increase. The aquifers of Curi, Yağlıdere, Gelevera, Akhisar, Yanbolu, Baltacı,İyidere and Fırtına are less affected by urban activities. Among them, Curi, Yağlıdere, İyidere and Fırtına aquifersare aquifers with high groundwater capacities. In order to be able to use the Eastern Black Sea coastal aquifers formany years, it is necessary to protect them in terms of quality and recharging.