Effect of urbanization on groundwater resources of Izmir city

Abstract

İzmir is the third largest city in Turkey. Fifty­six percent of the drinking water of İzmir city is provided from groundwater resources. Halkapınar (located on Bornova Plain) is one of the important groundwater resources areas. This region is providing 16 % of İzmir drinking resources. The water withdraws from the Halkapınar wells is about 30 million m3 in recent years. The groundwater levels of Bornova plain are range from 1 m to 10m. This plain had been used as agricultural lands until the 1950s, while today they have been opened for settlement. In 1965 Bornova accommodated half of its population in rural areas after receiving so much immigration. It was inevitable to open the city­centre to housing and to consider the surrounding village areas as urban areas. By the year 2000, the rural population had already been melted into the urban population. The agricultural areas in rural parts of the country will have completely disappeared in 50 years' time. Much of the surface of the plain is rendered impermeable by buildings, roads and surface coverings. Because of this covering, groundwater recharge is reduced and increases and accelerates runoff the plain. The groundwater recharge from precipitation was about 27 % in 1925, but this amount dropped to 13% in 2012. Groundwater recharge from precipitation will be 1% in 2030. Hydrodynamic of plain is change because of excessive urbanization. Groundwater level of the plain still high because tall building makes a barrier for groundwater recharge points.