What has been the flow regime of the rivers of Espírito Santo?
River flow is measured at specific measuring stations, or gauges. The discharge regime of the state of Espirito Santo, and the extension of the Rio Doce into Minas Gerais is defined by the discharge records from Agência Nacional de Águas (ANA). These records then provide the basis for the modeling that describes the overall hydrological cycle. Analysis of the overall flow records showed that the following stations had the most complete data records, and would be suitable for the modeling calibrations/validation process.
These river flow regimes, from the observed gauges, can be examined in detail in the interactive figure below.
Observed gauge flow from 1970 to 2007 for the seven gauge locations mapped above, interactively displayed to show yearly flow in relation to precipitation for the overall basin area. Y-axis presents natural logarithmic values for cubic millimeters per second flow. Interactions provided through mouse cursor location and mouse clicks on legend to toggle individual gauge station visibility. Note the natural logarithmic scale provided to show all gauge data on the same graph.
The data for these graphs can be downloaded for each river, by clickinbg on the resepctive links (as text files in Comma Separated Values format).
These are the following linear trends at the corresponding significance level for observed streamflow (from ANA) for 1970 – 2006.
|Years available||Gauge||Linear Trend (%/year)||Student-t Significance|
|1970 – 2006||Cachoeira||-0.0249||0.9|
|1970 – 2006||Valadares||0.3784||0.8|
|1970 – 2006||Guandu||0.0884||0.8|
|1970 – 2006||Itabapoana||-0.02424||0.8|
|1970 – 2006||Leopoldina||-0.0897||0.8|
|1970 - 2006||Rive||0.1582||0.6|
|1970 – 1994||Linhares||-1.023||0.5|
The increasing streamflow occurs at gauges that are West of the basin. This corresponds to increasing precipitation from 1970 – 2006. The gauge closest to the coast experiences the highest decrease in flows – this could be due to (a) undisclosed dams/reservoirs (b) increase in sediment impeding flow to the gauge (c) poor quality gauge data or (d) a combination of (a), (b) and/or (c).