Time-series variability of solute transport and processes in rivers in semi-arid endorheic basins: The Okavango Delta, Botswana

We investigated hourly time-series of total dissolved solids (TDS) in the Okavango River at inlet and outlet Delta (Delta) semi-arid Botswana. estimated solute flux into out Delta. Our objectives were to (1) document temporal variations solutes (represented by TDS) determine processes that control concentrations (2) quantify load The varied from sub-weekly monthly time frames, with a semi-annual increase controlled annual pulse flooding local rains. Variable interaction floods rains stores floodplains, hundreds thousands islands isolated saline wetland pools loading River. concentration-discharge relationship for showed timing delivery river which varies across is function spatial variability stores, availability heterogeneous activation hydrologic flow pathways connect stores. Of 329,200 Mg/y delivered Delta, 68,240 (21%) removed 260,960 retained, making sink. Annually, 87% are during flooding, 4% rainy season 9% other times. findings indicate perturbations connectivity watershed play significant role modulating transport rivers cycling arid watersheds. inform sampling regimes, water quality monitoring modeling