Investigating karst development using hydrological and hydrochemical characteristics of springs (case study: Roein basin in North Khorasan province)

In order to study the development of karst, using the hydrological and hydrochemical characteristics of the springs in Roein Basin, 19 springs were identified in the study area.To calculate and analyze parameters such as discharge and hydrograph of springs, Recession Coefficient, volume of dynamic storage, Estimate of recession coefficient, drawing Piper diagram, ratio of calcium to magnesium, saturation index, determining the type of reservoir rock. And the karst geomorphology of the study area was investigated.The hydrograph of the springs in the study area shows the delay time between the peak rainfall and the peak discharge in the springs, where the maximum discharge of the spring reaches its maximum with a delay of about two or three months. The low Recession Coefficient and the volume of dynamic storage of the aquifer indicate the low development of karst. The saturation index shows that the spring water samples collected from the study area are all saturated and supersaturated. Piper's diagram in the study area showed that most of the springs have bicarbonate-calcic-magnesic type. Based on the index of Ca/Mg ratio, they have a dolomite aquifer. The type of reservoir rock in the region showed that the type of reservoir rock in the region is dolomite and calcareous dolomite and the geomorphology and field observations in the region showed that there are no advanced karst forms in the region.It can be said that the karst system of the region is not developed and many karst geomorphological forms are not observed in the region.