The stream Titerno (30 kilometers) starts at an altitude of 1200 meters, at the foot of Monte Pesco Rosito in the district of Pietraroja.

After having run through the valley and collected other watercourses, it keeps its way between steep sides, arduous places and canyons which contributes to shape by digging the rock deeply, as in the gorge of Ponte Risecco, for a good five kilometres, in order to start again its course between the inhabited centres of Valle Telesina, before flowing into the Volturno.