Hydrogeology and the Declaration of Protection Area of Tavra Springs (Sivas - Turkey)

The basin of Tavra Springs located 7 km North of Sivas Province has a drainage area of 101 km2. Sivas City provides a portion of the drinking and potable water with the average flow (Q) of 880 l/s from groundwater (underground drainage) in the valley. The springs in this valley are generally located in the northwest and south of the valley. There is no single exit point of Tavra Springs. Some springs flow in the form of surface stream (surface water). The groundwater flow was measured in the collection chamber downstream of the valley. This study was conducted in order to determine the spring field and the protection of the borders of the Tavra Springs in accordance with “The Communication about Drinking Water Supply and the Aquifer Protection of Sources” protocol published in 10th October 2012, [10]. According to the reports in this type of springs, “Absolute Protection Area” is accepted to be 50 meters. Additionally, “First Degree Protection Area” is defined as an area beginning from “Absolute Protection Border” to the distance travelled by the infiltrated water into the aquifer in 10 days. In order to calculate the border of “First Degree Protection Area” of the Tavra Spring, one borehole having 35 meter in depth was drilled 130 m away from the upstream springs. The salt solution (500 kg salt/ 2000 l water) with electrical conductivity (EC) value of 222.000 μS/cm was injected and the changes in the electrical conductivity were then tested and monitored in the downstream springs. Moreover, this area was estimated by using the empirical equations derived from Darcy's formula. The results of these two methods (testing-monitoring, empirical estimation) were compared. As a main result of this study, the distance between “Absolute Protection Area” and “First Degree Protection Area” was determined to be 437 meters.