Hydrogeology of Karstic Springs in Kalaleh Region, Golestan Province

Kelale mountainous region is located in the east of the Golestan province. There are several karstic springs such as Zav, Aghsoo, Yal-cheshme in the region due to the existing karstic limestone and relatively high average precipitation value. The development of karstic formation in Kelale area and catchment area of four major springs has been investigated in this study based on geology, hydrogeologic and hydrochemical factors. In this area, springs are discharged from Lar, Tirgan, and Mozduran karstic formations and Sarcheshmeh shale formation. Different karst features such as closed depression, sinkhole, joint and fractures were observed in Lar formation during field investigation, then the Lar formation proposed as catchment area. The types of flow in all springs are conduit and diffuse flow. Zav and upper Yal-cheshme with three recession coefficient, are fed by a well-developed karstic aquifer; while the recession curve of Aghsoo and lower Yal-cheshme have one recession coefficient, indicating weaker karstic development in the basin. All the springs have the same origin and mainly have Ca-HCO3 water type. Cation exchange also affects the hydrochemical characteristic of the springs. All springs are super-saturated with calcite and dolomite but under-saturated with gypsum and halite.