Quantitative Analysis of the Impact of Climate Change and Human Activities on Runoff Variation in Akwa Ibom State, Nigeria

The non-parametric Mann-Kendall (MK) trend test, including the Sen's slope test and Pettitt's test, was used to determine trends, magnitudes, and change points in hydro-meteorological variables from 1972 to 2021. The slope change ratio of accumulative quantity (SCRAQ) method was then used to calculate the relative contributions of climate change and human activities to runoff variation in the Uyo-Itu river basin. Annual rainfall, maximum temperature, minimum temperature, and runoff showed significant increasing trends, whereas annual relative humidity, solar radiation, and potential evapotranspiration showed significant decreasing trends. Between 1992 and 2010, there were abrupt changes in hydro-meteorological variables. However, the runoff shift occurred in 2003. The time period under consideration was divided into two parts: baseline period A and change (impacted) period B. Climate change dominates runoff variation in period B, accounting for 103.6 percent of the variation, while human activities have a negative impact (-3.6%). The results indicate that climate change is the primary driver of runoff variation and that its impact is becoming more severe. Furthermore, the Budyko hypothesis was used to validate the contributions of human activities and climatic changes based on the SCRAQ method. The results showed that the contributions of human activities and climatic changes computed using the SCRAQ method are comparable with those computed using the sensitivity-based method. From this study, it can be concluded that assessing the influence of climate changes and human activities on variations and identifying the major driving forces causing the variations are critical for more efficient water resources management for sustainable economic growth