A study of the variability of lag time as measure of hydrological response in urban catchments

Abstract

The Inter-Amount Times (IAT) adaptive sampling technique has been used for the analysis of hydrological response in urban areas. The analysis of hydrological response often requires the correct use and interpretation of temporal parameters such as lag time adapted to complexities and requirements of urban environments.
In this thesis, the development of a hydrological response methodology that avails itself of the statistical framework of IAT for the hydrological response analysis is suggested by proposing a new lag time definition based on IAT. This new definition was evaluated through the analysis of discharge and precipitation time series of fifteen years. The IAT lag time results were compared against classical methods used to define and compute lag time such as centroid-to-centroid (C-to-C) and peak-to-peak (P-to-P) methods. Finally, a validation procedure is carried out to assess the validity of the proposed IAT lag time definition.
Results from the computation of hydrological response values using each of the three methods showed some relevant similarities but also exhibited varying behaviours and limitations based on the proposed methodology for the definition of the hydrological events. Statistical distributions of the IAT lag time method and C-to-C method had similar distributions, in contrast to what was observed for the statistical distribution of P-to-P values. Results from the IAT lag time method suggested a more stable and flexible methodology compared to the classical methods.
The IAT lag time method can potentially be used to have a more dynamic and tailored interpretation of the hydrological response behaviour in urban areas. Experimental work is required to test the method in other urban areas to confirm the validity of the results of this approach used to study the hydrological response of urban catchment.