In South America are located many prominent basins in the world. These resources are extremely important to society. Their availability, as well as risks of droughts and floods can be impacted by the climatic variability and thus significantly affect the biotic and anthropic environment linked to them. Since climate studies point to changes in the climate due to the emission of greenhouse gases (IPCC 2013), simulations that indicate regions where there is greater sensitivity can contribute to early visions of problems and how to solve them.
The average sensitivity of the evapotranspirations in each discrete minibacia and the average flow sensitivity in each section of these basins were calculated from simulations with rainfall scenarios in the integrated model of the South American basins (Siqueira et al., 2017). These values are available in shapefile files at the end of this page. The following maps illustrate in red the places with greater sensitivity, while in green the smaller sensitivities.
The sensitivity value is a dimensionless number, which indicates the proportionality between the percentage variation of the parameters analyzed from the rainfall variation. That is, for a sensitivity of 0.5 evapotranspiration, if local precipitation increases by 20%, evapotranspiration should increase 0.5 × 20% = 10%.
The simulations were run for variations of 20% for more and for less in the precipitation and compared with the simulated for observed rains. The mean value between the two absolute variations in each minibacia was calculated, followed by the sensitivity value, defined by ΔQmed / Qmed divided by ΔPmed / Pmed (Chiew 2006) in the case of flow and ΔEvapmed / Evapmed divided by ΔPmed / Pmed in the case of evapotranspiration. More details of the method, references and other results can be found in the reference articles.
It is intended to contribute with data generated for possible uses such as:
– In the face of predictions of drier or wet years, we can estimate the impact on the flow or evapotranspiration of the region, multiplying the percentage of increase or reduction predicted in the rain by the value of sensitivity indicated in the table of attributes.
– Agile assessment of the impact of climatic changes indicated by IPPC studies in river basins, dispensing, in the first moment, complex simulations to evaluate the changes in the flow and evapotranspiration.
In the link below you can find a shapefile file containing the watersheds of South America discretized in minibacias. In the attribute table they are identified by “Mini” and display the sensitivity in the last column: “VAR” for the sensitivity file of the evapotranspiration and “Sensib_med” in the file table of the sensitivity of the flow.