The Arapliyska reka (Bulgarian: Араплийска река) is a river in southern Bulgaria, a left tributary of the river Popovska reka, itself a left tributary of the Tundzha of the Maritsa drainage, with a length of 42 km.

[1] The river takes its source under the name Golyama Derbventska reka at an altitude of 484 m in the Dervent Heights, about half a kilometer southwest of the peak of Charakbaba (540 m) on the Bulgaria–Turkey border.

It flows in a narrow forested valley initially in western direction until the village of Valcha Polyana, it then turns north until Razdel and finally northwest until Chernozem, where it is joined by the Boyalashka reka.

The Arapliyska reka has predominantly rain feed with high water in autumn and winter.

There are five settlements along its course, one town and four villages: Golyam Dervent, Valcha Polyana, Razdel and Chernozem in Elhovo Municipality.