Quantification of Long-Range Persistence in Drought Series forNorthern Nigeria

Abstract

The seeming frequent occurrence of hydrological extremes (e.g., flood and drought) of latehasbecome a matter of serious concern within the hydrological community. In viewof this, thestudy attempted quantification of long-range persistence in drought series for northern Nigerian. The protocol employed for the analysis entailed (1) Rescale range statistics (2) Aggregatedvariance method and (3) Detrended fluctuation Analysis. The result shows presence of long-termmemory in monthly meteorological drought series. The extent of prominence is distinct inhydrological Areas 1, 3, and 8 with an average intensity of 0.67 while the regionalised intensityis 0.68; that is across Northern Nigeria. For analysis of persistence/long-termmemory, theDetrended Fluctuation Approach appeared to be most  suitable as result here mimic previoussubmissions.For instance, DFA, AVM and R/S, show the existence of admixture of mildtostrong  persistent in all the hydrological areas (HAs), particularly for SPI-1, yielded 80%, 79.22%and 70% respectively. Persistency gradual  decreases from strong to anti-persistence as temporal accumulation increases from SP-1 to SPI-12, more obvious in AVM and R/S and less  obviousinDFA protocol. This sailent attribute supported the fact that the choice of appropriate temporal resolution for long-range  persistence analysis is vital. As wrongly selected time tuning resolutionmay mar the authenticity of a given propounded findings. It is  recommended, that further relatedstudies should be tailored towards determination of appropriate time tuning resolution for longrange  persistence as a function of admixtures of varying-variance vis-à-vis heteroscedasticityindrought series, because of high volatility and  presence of leptokurtic behaviour of hydro-climaticprocesses especially in the light of climate change.