Spatiotemporal river–aquifer interactions of a large tropical dryland river with high anthropic intervention

ABSTRACT This study analyses the spatiotemporal river–aquifer interactions in a large dryland river with high anthropic intervention. Measurements of water level and flow rate were performed and analysed together with secondary data on hydrogeology, water use and satellite images. Average transmission losses ranged from about 12 to 28% of the river inflow, while transmission gains ranged from 10 to 34%. Transmission losses occurred at the beginning of the rainy season (rainfall ≤ 10 mm/d), while the transmission gains were preponderant after intense rainfall events (> 20 mm/d). A direct relationship between the transmission losses/gains and river inflow was also observed. Linear equations were adjusted to estimate the order of magnitude of transmission losses (R2 > 0.85) and gains (R2 > 0.60). The transmission loss equation was validated for rivers in similar regions (R2 ≈ 0.85). A conceptual model is proposed to describe river–aquifer interactions in large dryland rivers.