The spatial variability of runoff and precipitation in the Rio de la Plata basin

Abstract

Abstract A few aspects of spatial variability, connected with climate variability, in the Rio de la Plata basin are analysed through changes in the basin runoff considered as indicative of the annual integrated precipitation. Those changes contain better information on climate variability than the sparse records of precipitation and temperature in view of the high spatial and temporal variability of those parameters. The precipitation data are applied in the most active zones of the basin, however, in order to assess aspects of hydrological variability that the lack of data causes in the studied region. The hydrological series employed correspond to average monthly and yearly flows at stations selected along the main rivers, both due to stability in their gauging stations and to the availability and quality of data for the 1931–1992 period. This period includes the longest series of simultaneous observations for the stations selected. Similar approaches were applied to the series of precipitation. Through basic statistical analysis, and from the annual evolution of flows and precipitation, the study of the relationship between rainfalls in the area and flows at separate hydrological stations (taking also the annual cycle of precipitation and flows into account), nine hydrological areas were detected. From those areas, well separated from each other, the spatial variability for the Rio de la Plata basin was characterized.