Hydrometric Data Rescue in the Paraná River Basin

Abstract

The Parana River streamflow is the third largest in South America and the sixth largest in theworld. Thus, preserving historical Parana hydrometric data is relevant for understanding South American andglobal hydroclimate changes. In this work, we rescued paper format data of daily Parana water level observationstaken uninterruptedly at Rosario City, Argentina, from January 1875 to present. The rescue consisted ofthe following activities: (i) imaging and digitization of paper format data, (ii) application of quality checks andhomogeneity tests to the digitized water levels, and (iii) consideration of errors caused by gauge sinkings thatmay have occurred from 1875 to 1908. In addition, a rating curve was obtained for Rosario and it was used toconvert water levels into discharges. The rescued water level observations and their associated discharge dataprovide the longest (last 143 years) continuous hydrometric records of the Parana basin. The usefulness ofthese records was demonstrated by showing that the Parana-Pacific Ocean links observed after 1900 in previousstudies are also evidenced in our nineteenth-century discharge data. That is, high Parana discharges coincidedwith El Ni~no events and with El Ni~no-like states of the Interdecadal Pacific Oscillation (IPO), whereas lowdischarges coincided with La Ni~na events and with La Ni~na-like IPO states.