Abstract:
Global impacts of drought conditions pose a major challenge towards the achievement
of the 2030 Sustainable Development Goals. As a result, a clarion call for nations to take actions
aimed at mitigating the adverse negative effects, managing key natural resources and strengthening
socioeconomic development can never be overemphasized. The present study evaluated hydrological
drought conditions in three Cape provinces (Eastern, Western and Northern Cape) of South Africa,
based on the Standardized Streamflow Index (SSI) calculated at 3- and 6-month accumulation periods
from streamflow data spanning over the 3.5 decades. The SSI features were quantified by assessing
the corresponding annual trends computed by using the Modified Mann–Kendall test. Drought
conditions were also characterized in terms of the duration and severity across the three Cape
provinces. The return levels of drought duration (DD) and drought severity (DS) associated with
2-, 5-, 10-, 20- and 50-year periods were estimated based on the generalized extreme value (GEV)
distribution. The results indicate that hydrological drought conditions have become more frequent
and yet exhibit spatial contrasts throughout the study region during the analyzed period. To this end,
there is compelling evidence that DD and DS have increased over time in the three Cape provinces.
Return levels analysis across the studied periods also indicate that DD and DS are expected to be
predominant across the three Cape provinces, becoming more prolonged and severe during the
extended periods (e.g., 20- and 50-year). The results of the present study (a) contribute to the scientific
discourse of drought monitoring, forecasting and prediction and (b) provide practical insights on
the nature of drought occurrences in the region. Consequently, the study provides the basis for
policy- and decision-making in support of preparedness for and adaptation to the drought risks in
the water-linked sectors and robust water resource management. Based on the results reported in
this study, it is recommended that water agencies and the government should be more proactive in
searching for better strategies to improve water resources management and drought mitigation in
the region.
