Resumen de Recession curve analysis of major karstic springs at the Lasem area (north of Iran)

Abdollah Shamsi, Gholam Hossein Karami, Azizollah Taheri

• The hydrograph recession analysis of 15 karst springs used to evaluate the karstic aquifers of Lasem area, 70 km northeast of Tehran. Karst springs discharge have been measured from April 2015 to June 2016. Tectonic activities lead to the partitioning of the karstic aquifers to north and southern sectors. Discharge of the spring’s ranges from 2500 to 20 L/s and 200 to 6 L/s in peak and base flow time respectively. The springs of the northern sector (NS) have lower discharge in comparison to the southern sector (SS). Karst springs of SS have three distinct discharge segments while those in NS have just one discharge regime. The main reason for such distinct discrepancy is related to the different degree of karstification and recharge characteristics. Such that the karst development in SS is very high and the conduit flow is dominant. In contrast, karstification has infinitesimally occurred in NS and dominant flow is diffuse. Recharge on SS occurs dominantly by springtime snowmelt while NS feds by early melt in wintertime.