Tens of thousands of dams were built around the world to reduce flood risks and maximize the benefits of limited freshwater resources. In Brazil, the main and largest reservoirs are related to hydropower plants. Improving the understanding of reservoir dynamics is important not only to evaluate their impact in the flow regime of Brazilian rivers, but also to simulate the combined effect of constructing new dams and potential alterations under future climatic conditions. Here, we analyzed how an ideal representation of reservoirs in terms of forced discharge would improve a previously calibrated hydrological model under the Brazilian domain. We forced the continental-scale version of the MGB hydrological model on observed reservoir outflows from 109 hydropower dams, which are part of the Brazilian National Interconnected System (SIN) controlled by the National System Operator (ONS). Model simulated flows were replaced by the reservoir outflows in all these locations and were compared to the original discharge. The forced discharge simulation presented a mean improvement for Kling-Gupta Efficiency (KGE) of 21%, when compared to the original (naturalized flow) model. This analysis was a preliminary step towards an explicit representation of the reservoirs in the model; the representation will be conducted in a future study.
Here, we provide a dataset of simulated discharges for South America encompassing the period between 01-Jan-1990 and 31-Dec-2009. River discharges are estimated by running the MGB hydrologic-hydrodynamic model with daily time step forced with rainfall derived from gauge, satellite and reanalysis data. South America was discretized into 33,749 irregular computational elements (i.e., unit-catchments based on topography and river length), and the model computes a time series of discharge corresponding to the outlet of each of these unit-catchments. The data is free access and should be used only for research activities and other educational purposes. Authors are not responsible for the use of this dataset. It is worth mentioning that these estimates are part of a hydrological model run, assuming several hypotheses that must be understood before its use.
In the link below, you will find a NetCDF file with river discharges forced by the MGB model and also a Matlab code example for its reading. Data are arranged in a 7305 (rows) x 33,749 (columns) matrix with columns representing each unit-catchment and associated river reach and rows representing each simulation day (01-Jan-1990 to 31-Dec-2009).
The NetCDF file also provides the upstream drainage area and the centroid coordinates of each unit-catchment. There are many free softwares available on the internet that can also read NetCDF files. You can find a list of these softwares here: https://www.unidata.ucar.edu/software/netcdf/software.html
In the next link you can download the shapefiles of river networks and unit-catchments used by the MGB continental model. In the attribute table, the “UC” indicates the unit-catchment index that is related to columns of the discharge matrix (from NetCDF file), while the upstream drainage area to the outlet of unit-catchment is indicated by the “_Upstr_area” column.
Please cite the following paper whenever you use this dataset:
Passaia, O. A., Siqueira, V. A., Brêda, J. P. L. F., Fleischmann, A. S., and Paiva, R. C. D. Impact of large reservoirs on simulated discharges of Brazilian rivers, RBRH, submitted.
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