Discharge Regime

regua

What is the current hydrologic regime of Espirito Santo and the Rio Doce?

      Knowing the actual hydrologic regime is the key first step in building models of the dynamics of water movement. This starts with climate observations - how much is it raining where with what temperature. Then, river flow is measured at specific measuring stations, or gauges. The flow records are then available through the Agência Nacional de Águas (ANA). The location of dams affected the flow regime, and must be taken into consideration in the flow routing modeling. 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 ANA. These records then provide the basis for the VIC 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.

 

 

 

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.

Download observed data by gauge station. Text files in Comma Separated Values format.

Cachoeira
Guandu
Itabapoana
Leopoldina
Linhares
Rive
Valadares

     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).