Development of an operational low-flow index for hydrological drought monitoring over Europe

A near-real time monitoring of hydrological drought requires the implementation of an index capable of capturing the dynamic nature of the phenomenon. Starting from a dataset of modelled daily streamflow data, a low-flow index was developed based on the total water deficit of the discharge values below a certain threshold. In order to account for a range of hydrological regimes, a daily 95th percentile threshold is adopted, which was computed by means of a 31-day moving window. The observed historical total water deficits were statistically fitted by means of the exponential distribution and the corresponding probability values are used as measure of the hydrological drought severity. This approach, has the advantage to directly exploit daily streamflow values, as well as to allow a near-real time update of the index on regular time steps (i.e., dekadal). The proposed approach was implemented on discharge data simulated by the Lisflood model over Europe during the period 1995-2015; its reliability was tested over four case studies detected within the European drought reference database, as well as against the most recent summer drought observed in Central Europe in 2015. These validations, even if only qualitative, highlighted a good capability of the index to capture both the timing (starting date and duration) of the main past drought events and the spatial evolution of the most recent one in a simulated near-real time test case, suggesting the suitability of the index for an operational implementation within the European Drought Observatory.

CAMMALLERI Carmelo;  VOGT Juergen;  SALAMON Peter; 

2016-11-16

TAYLOR & FRANCIS LTD

JRC97974

0262-6667,   

http://www.tandfonline.com/doi/full/10.1080/02626667.2016.1240869,    https://publications.jrc.ec.europa.eu/repository/handle/JRC97974,   

10.1080/02626667.2016.1240869,