*4.2.1 Decades*

The occurrences of drought within decades varied during the period of study from one sub-area to another. This means the drought percentages of occurrence are not the same. Kano and Nguru experienced drought in four decades of the six decades considered, that is 66.66% drought to 33.33% of wetness. The decades 1961–1970, 1971–1980, 1981–1990, and 2011–2020 were those of droughts with that of 1981–1990 being significant. Other decades were wet with 2001–2010 being significant (**Table 3**). In Nguru, the first and last decades of the study were wet,


*\*Significant at p < 0.05.*

*Source: Section 3.2.*

*Yel, Yelwa; Sok, Sokoto; Gus, Gusau; Kad, Kaduna; Kat, Katsina; Kan, Kano; Ngu, Nguru; Pot, Potiskum; Mai, Maiduguri.*

with that of the last decade being significant. Other decades were those of drought with that of 1981-1990 being significant.

In some sub-areas such as Yelwa, Kaduna, Katsina, and Potiskum, the drought decades constituted about 50% the same as the wet decades (50%), although the decades were not the same in all the sub-areas of study. In Yelwa three consecutive decades of 1961–1970, 1971–1980, and 1981–1990 were those of drought with the value for 1981–1990 being significant. Other decades were wet with that of 1991– 2000 being significant. Katsina sub-area also experienced the same situation, and the decades with droughts were 1971–1980, 1981–1990, and 1991–2000 with the last two being significant. These decades were also those of drought in the Potiskum sub-area, although without any being significant. Other decades were wet and were not significant in both sub-areas. In Kaduna, the drought decades were 1981–1990, 1991–2000 and 2001–2010 although with values that were not significant. Other decades in this sub-area were wet with the last, 2011–2020 being significant.

The situations experienced in Sokoto and Gusau sub-areas were slightly different from the above. Drought dominated in 1971–1980 for Sokoto and 2011–2020 for Gusau, while the decade 1981–1990 was a drought decade in both sub-areas although it was significant in Sokoto but was not in Gusau. Other decades were wet for both sub-areas. This indicates that the drought decades constituted about 33.33% while the wet decades constituted about 66.66%. Maiduguri sub-area had 1981–1990 as a significant drought decade. Other decades were wet although not significant. This indicated 16.66% of the decades were drought-dominated. The above percentages of drought and wetness do not suggest a permanent shift in


#### **Table 4.**

*Values for student's* t*-test (30 years non-overlapping).*

*Meteorological Drought and Temperature in Sudano-Sahelian Region of Nigeria… DOI: http://dx.doi.org/10.5772/intechopen.100108*

climate. It shows more of an alternation between drought and wetness and therefore climate variability.
