Estimation of Runoff Coefficient in Karstic Area (A Case Study: Delibajak Sepidar, Kohgiluyeh and Boyer-Ahmad province)

Evaluation of infiltration and runoff in karstic areas is considerably important. These processes in karstic areas are more different from the other land coverages. Due to variation of factors affecting the infiltration and runoff in karstic areas, a specific formula cannot be set for these processes. In this study the amount of runoff and infiltration in a karstic catchment, named Delibajak in central Iran, were evaluated in both basin and plot scales. Precipitation and runoff components were continuously measured over the basin during research period and the runoff coefficient was estimated based on the collected data. Also, in plot scale, these components were evaluated on soil and rock coverages in 25 tests using sprinkler. Evaluated infiltration and runoff data in the basin-scale, show a very high infiltration capacity in Delibajak catchment, with very small runoff coefficients (1.5, 0.54 0.45 for events of 133, 130 and 95 millimeters of rain, respectively). Results of sprinkler data indicate a wide range of infiltration rate in Delibajak basin from almost zero to 40 percent.