Climate and Hydrology

The uses of water resources depend on the hydrological behavior of rivers and river basins. When the use of water are planned, the risk of future hydrological behavior of the rivers and basins must be assumed. The hydrological behavior of flow and precipitation depends on the climate, which tends to be stationary (the characteristics of the variable do not vary with time). However, with the development of society, non-stationary processes are observed due to one or more of the following factors:

• Land use change;
• Hydraulic works;
• Variability or climate change.

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Climate and Hydrology

  • Hydroclimatic prediction
  • Macrodrainage studies
  • Water availability and sustainability
  • Streamflow forecast
  • Soil moisture forecast

Risks and uncertainties

The understanding of natural and anthropic processes is essential for assessing project risk and reducing uncertainty. Risk is the probability of occurrence of events that projects are not prepared to them. Uncertainty is the difference between the true and calculated risk of a project due to errors in the data, in the considerations of the hydrological series with non-seasonality behavior.

Usually, the hydrological series have seasonal behavior (variability within the year), interannual (between few years) and interdecadal (behavior between decades or more). A prolonged interdecadal trend may compromise a region. One example is part of the north and northeast area of Brazil, such as the São Francisco and Tocantins river basins, which go through a long period with flow moving averages below the previous period since 1991. On the other hand, since 1970, the south and southeast region have shown an above average trend until recently. These constraints can compromise the water sustainability of a region.

Climate influence

The assessment of the land use impact and climate change is the basis for the sustainable development of river basins. For the analysis of the climate influence on water resources the water variables are collected and monitored in different systems, extrapolation of hydrological and climatic series, regionalization of variables, impact assessment and management of land use change, evaluation of extreme flows (floods and droughts), flow regularization, integrated processes evaluation, such as interception and evaporation.

The data generated are analyzed and strategies can be defined for different scenarios in order to mitigate impacts, improve water availability and protect the river basin from drought or flood events.