User-oriented hydrological indices for early warning systems with validation using post-event surveys: flood case studies in the Central Apennine District

Abstract. Floods and flash floods are complex events, depending on weather dynamics, basin physiographical characteristics, land use cover water management. For this reason, the prediction of such events usually deals with very accurate model tuning validation, which is site-specific based climatological data, as discharge time series or flood databases. In work, we developed tested two hydrological-stress indices for detection in Italian Central Apennine District: a heterogeneous geographical area, characterized by topography medium-to-small catchment extension. The proposed threshold-based considering operational requirements National Civil Protection Department end-users. They calibrated through application signal theory, order to overcome data scarcity over ungauged areas, well incomplete series. validation has been carried out case study basis, using reports from various sources information, hydrometric-level series, represent actual hydrological quantity monitored operators. Obtained results show that overall accuracy greater than 0.8, false alarm rates below 0.5 probability ranging 0.51 0.80. Moreover, different nature suggests their complementary way, index drained precipitation appears be more sensitive rapid propagation small tributaries, while discharge-based particularly responsive main-channel dynamics.