Investigation of hydrological characteristics of Damghan Cheshmeh-Ali karst aquifer

Damghan Cheshmeh-Ali spring with average daily discharge of 140 lit/s plays main role in supplying the domestic and agriculture water demands in this area. In this study, daily precipitation and discharge data series from 2001-2010 were used for investigating of hydrological characteristics of the karst aquifer connected to this spring. Mangin’s classification method indicates that the unsaturated zone of the Cheshmeh-Ali karst aquifer has more karstification degree compared to the saturated zone. Cross correlation analysis between cumulative rainfall (daily to 360 days) and daily spring discharge data indicated that the rainfall series of current day to 300 days have more correlation with the spring flow in current day. In addition, frequency analysis of drought hydrological carried out on the spring low flow and with duration of 3, 7, and 10 days indicated that discharge with probability of 99% is obtained as 350, 262, and 213 lit/s respectively for duration of 3, 7, and 10 days. Whereas, significant difference is observed between the predicted discharge with periods of 3, 7, and 10 days for less than 5 years return duration.