Groundwater recharge assessment in the karst aquifers of North Khorasan, Iran using APLIS method

Abstract

In order to optimize consumption, maintenance and control of underground water, an estimation of the groundwater recharge is highly important. Therefore, this research investigates the aquifers in North Khorasan province using APLIS (Applied Physics Laboratory Ice Station) based on a GIS. For this purpose, several significant hydrogeological parameters affecting groundwater recharge including altitude, slope, lithology, soil type and infiltration are considered. Therefore, corresponding layers for these parameters were provided and prioritized. In the end and after integrating the data, the recharge rate was measured qualitatively and different regions were mapped accordingly. The results indicate that the annual average values on a 30-year timescale in karst formations of the North Khorasan vary between 103 mm and 362 mm, with the mean value of 192 mm. Minimum, maximum and mean recharge rates of aquifer in the study area are 42 %, 73 % and 54 %, respectively. Also, aquifer recharge potential in 83 % of the karst formations is moderate while it is high for the remaining. Low recharge regions correlate to lower karst limestone and dolostone areas in the lower altitudes while high recharge regions represent upper karst limestone and dolostone areas, especially in the high altitudes.