ABSTRACT Drainage basins of Agia Triada and Skarmaga streams lie on Northern Attica (Greece) and their torrents cross the city of Avlon. They belong geotectonically to the Sub Pelagonic zone and consist of schists and sandstones. The paper deals with the geomorphologic and statistical study of the drainage systems, as well as the calculation of the peak storm in the river exits. The statistical analysis showed that the drainage systems were influenced by lithology, as well as all the systems were in advance maturity stage of development. The peak storm runoff that was estimated, based on the land use before and after the disastrous to the forest fire and concerns the extreme values of the maximum probable peak storm runoff, with a 50 years recurrence period. The flood levels of the torrents and streams should be taken seriously into consideration in order to foresee and anticipate the necessary sewage and drainage work systems. Maintenance of the channels are finally suggested. KEYWORDS: peak storm runoff, drainage basins, SCS method Geomorphological investigation of the drainage networks and calculation of the peak storm runoff of Skarmaga and Agia Triada streams Odysseus Manoliadis Department of Geotechnology and Environmental Engineering Technological Educational Institute, Koila 50100, Kozani, Greece e-mail the author Kostaninos Sachpazis GEODOMISI S.A., 32 Marni Street, Athens 10442, GREECE e-mail the author Submit discussion