The generation of runoff through ephemeral streams

Ephemeral streams are elements of the surface drainage network that are normally dry and that occasionally, due to extreme rainfall events, may drain relevant discharges. They are largely diffused in karst areas, characterized by the absence of active stream networks and due to their extremely rare drainage. Their hydrograph in particular may be quite singular and different from the classic IUH. The work compare the hydrographs returned by the classic IUH approach with those obtained by an integrated hydrological-hydraulic approach for ephemeral streams characterized by quite small catchments, called “lame” and located in lower Murgia area (south east Italy). In particular, the peak discharges and the delays of the discharge generation through the ephemeral streams will be carefully analyzed. The differences are relevant especially for rainfall characterized by medium return periods, showing how the classic IUH approach could be completely unreliable.