Drought assessment and monitoring using meteorological indices in a semi-arid region

In the last decades a big interest was given to climate changes and especially drought monitoring. Defined as a natural hazard, and characterized by a prolonged absence, a marked deficit or a low precipitation distribution compared to the normal climate, drought may have several impacts on agriculture and hydrology. The drought characterization becomes possible with the initiation of the meteorological, agricultural and hydrological drought indices. Algeria is concerned by this phenomenon, because drought periods have begun since 1975. Deciles, Standardized Precipitation and Reconnaissance Drought Indices have been used to assess the meteorological drought in the world and they show their performance, why they have been chosen to study Wadi Djelfa-Hadjia sub-basin. The two first indices are based on precipitation only. However the RDI uses precipitation and the potential evapotranspiration (PET). Several methods can be used to estimate PET, but Hargreaves method is more accurate for semi-arid regions. The correlation between the SPI and RDI indices is good in the different time scales confirming their performance. The RDI gives the greater number of drought months, but both methods show the same drought durations and severity as the results of the Deciles index.