Hydroclimatology of the Kaduna River Basin

This study examined the hydroclimatology of the Kaduna River Basin (KRB) in northern Nigeria. In achieving this, monthly data on temperature (T) and rainfall (P) were sourced from ten hydrometeorological stations across the basin from 1990 to 2018. DrinC (Drought Indices Calculator) software was deployed to calculate Potential Evapotranspiration (PET) adopting Thornthwaite approach. Water Balance (WB) model was used further to estimate other WB components i.e. soil moisture (SM), actual evapotranspiration (ETa), Water surplus (S) and Runoff (R). WB components are used to examine the temporal and spatial variability of the KRB for hydrological years (1990-2018). KRB was divided into two sub-basins (Lower and Upper KRB). The WB analyses indicated the peak of R generally occurs during the wet season (i.e. April through October) most especially at the Upper KRB. The study further reveals that the runoff efficiencies imply that <44% of annual P results in R at the upper KRB while <27% of annual P results in R at the lower KRB. The study shows that SM utilization occurs mostly towards the end of the year and at the early months (i.e. November through March) across the basin while the majority of S is generated during wet season months, particularly from April through October when ~95% of S occurs on average with the peak S in August. The results of this study provide a baseline understanding of the hydroclimatology of the KRB which can be used as a starting point for further analyses, especially for water resources management.

Detecting Changes in Hydro-Climatic Variables during the Last Four Decades (1975-2014) on Downstream Kaduna River Catchment, Nigeria

This study aimed to detect trends in the long-term hydro-climatic series using non-parametric methods. The annual and seasonal linear trends of rainfall, temperature, runoff, water level and evaporation were analysed for stations in downstream Kaduna River Basin during 1975-2014. The non-parametric Mann-Kendall and Sen’s estimator of slope procedures were adopted to identify if there exists an increasing or decreasing trend with their statistical significance at 95% level of confidence. The datasets were checked to account for auto-correlation prior to determining trends using Mann-Kendall test. The existence of abrupt changes was detected by means of Cumulative Sum Charts and Bootstrapping analysis. The results of study indicated increasing trends for seasonal and annual temperature and runoff series. Water level and evaporation revealed statistically decreasing trends both on annual and seasonal periods. However, for the period 1975 to 2014 no significant distinctive trend was observed for rainfall at the investigated stations. Change-points in time series were identified in all the investigated hydro-climatic records for the sub-basin. Generally, the detection of the trend for hydro-climatic variables by Mann-Kendall test conforms to Sen’s test results. It is concluded that the basin is sensitive to climate variability and water stress impacts which will affect food security. So, it would be necessary to make adjustments in the adaptive water-use strategies being adopted at present in the catchment.

Households Vulnerability and Adaptation to Climate Variability Induced Water Stress on Downstream Kaduna River Basin

Water stress is one of the risks emanating from worsening climatic variations. It poses serious threats on vulnerable continents, people and livelihoods globally. However, little information is available on how the specific climate threat is impacting people’s livelihoods and water resources on different temporal and spatial scales in Nigeria basins. This study aimed at investigating household vulnerability and adaptation to water stress induced by climate variability on a downstream Kaduna River basin with the goal of supporting/facilitating climate change adaptation. The research analyzed hydro-climatic data and employed vulnerability-based framework consistent with stakeholders’ participatory approach, within the context of current climate conditions experienced, and/or water stress conditions already affecting household livelihoods in six communities at three study sites;Shiroro, Gbako and Lavun, and adaptive strategies engaged to deal with water stress. Findings revealed that households have been exposed and experienced changes in water availability through variations in rainfall, temperature and runoff. Consequently, these changes have impacted on food production and livelihoods. Households have individually and collectively employed adaptation techniques which are reactive, short-term indigenous coping strategies usually adopted during periods of stress to minimize water-related vulnerabilities. The study demonstrated how an understanding of the local household vulnerabilities will enable the recognition of early indicators of water stress in addition to the occurrence of extreme events. Overall, households’ vulnerability decreased from one village to another due to differences in sensitivity to stress, access to resources and local institutional capacity. Resilience of households can be increased through early warning system during flood events, providing access to water from rainwater harvesting techniques, and integration of climate change adaptation into policies regarding development initiatives especially in the area of agriculture.