Investigation of Hydrogeological speafications of karstic areas,using dye tracing – A case study of Garin area
|Location||The 24 Symposium of Geosciences|
|Holding Date||18 August 2007|
The study area that consists of Garin and Mishparvar mountains , is located at the south of Nahavand city (south west of IRAN).Calcareous formations of jourasic- cretaceous age , created a very important karstic aquifer, that is the source of large springs and rivers in this area; the flow rate of some of these springs, such as Gamasiab, is more than 4m3/sec.
Dye tracing method was used to study the followings:
- finding hydrogeological relation between injection points and springs,
- determination of drainage basin of springs,
- determination of flow direction and velocity of underground water and;
- determination of coefficient of dispersion of dye tracer in the proposed area.
In this study 12kg Uranine was injected into the biggest sink hole in Garin mount.
Then, samples from 12 points (springs, river &boreholes) were taken. After analysing of water and activated charcoal samples, the tracer was only detected in two sampling points. It shows that there is no hydrogeological relation between injection point and other sampling points. Therefor, the direction of water movement in studied karstic area is toward north west and along Garin mount and its parallel faults.
Numerical data analysis shows that average time of delay in karstic systems is about 60 days. Based on the first observation of dye tracer and the time of arrival of dye tracer to average concentration, the probable velocity of water is estimated of 1.72cm/sec and 0.24 cm/sec respectively.The coefficient of dispersion of dye tracer in the system is calculated as 0.3 km2/day