Abstract
Abstract. Despite the great scientific and technological advances in flood hydrology, everyday engineering practices still follow simplistic approaches that are easy to formally implement in ungauged areas. In general, these "recipes" have been developed many decades ago, based on field data from typically few experimental catchments. However, many of them have been neither updated nor validated across all hydroclimatic and geomorphological conditions. This has an obvious impact on the quality and reliability of hydrological studies, and, consequently, on the safety and cost of the related flood protection works. Preliminary results, based on historical flood data from Cyprus and Greece, indicate that a substantial revision of many aspects of flood engineering procedures is required, including the regionalization formulas as well as the modelling concepts themselves. In order to provide a consistent design framework and to ensure realistic predictions of the flood risk (a key issue of the 2007/60/EU Directive) in ungauged basins, it is necessary to rethink the current engineering practices. In this vein, the collection of reliable hydrological data would be essential for re-evaluating the existing "recipes", taking into account local peculiarities, and for updating the modelling methodologies as needed.
Highlights
Disasters caused by large floods increase worldwide as a result of the changing environment, despite better infrastructures, better forecasting systems and better urban planning and management
Taking as example the time of concentration, one of the most important parameters in flood modelling, we evaluate the performance of some widely used formulas against a large data set of peak flows from Cyprus
A transformation of point estimates is essential to account for the spatiotemporal variability of rainfall across the river basin, which is typically achieved by applying a reduction coefficient, called the areal reduction factor (ARF)
Summary
Disasters caused by large floods increase worldwide as a result of the changing environment (urbanization, deforestation), despite better infrastructures, better forecasting systems and better urban planning and management. Taking as example the time of concentration, one of the most important parameters in flood modelling, we evaluate the performance of some widely used formulas against a large data set of peak flows from Cyprus. An important reason for this method’s attractiveness to hydrologists and to authorities alike is certainly its simplicity: the model consists of the single equation This equation purports to estimate the peak discharge Qp from a drainage basin of area A – the “loss” characteristics of which (infiltration etc.) are (supposedly) encapsulated in the constant dimensionless runoff coefficient C – when the drainage basin receives a gross rainfall of constant intensity i over a time period at least equal to the basin’s time of concentration tc.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
