Randomized trial examines drivers of water quality in a Nigerian reservoir cascade, suggesting timing over location matters.
Key Points
This research analyzes how temporal, spatial, land-use, and climate factors influence water quality in a reservoir cascade.
Conducted monthly water-quality surveys at six sites spanning two dams and three habitat types from April 2024 to March 2025 (n=72 samples).
Calculated a modified National Sanitation Foundation Water Quality Index (WQI) for each sample.
Utilized variance partitioning, exploratory Granger causality testing, and changepoint detection methods to examine the relative contributions of various drivers.
Temporal variation explained 28.3% of the variance in water quality; spatial factors accounted for 1.8%, and land-use effects for 0.4%.
No significant climate-water quality relationships were found across 480 stratified tests, classifying this as hypothesis-generating.
WQI, electrical conductivity (EC), and relative humidity (RH) showed the highest changepoint detection rates (71.4%), proposed as sentinel parameters for monitoring.