Climate downscaling over South America for 1971–2000: application in SMAP rainfall-runoff model for Grande River Basin

• Published in: Climate dynamics Vol. 52; no. 1-2; pp. 681 - 696
• Main Authors: da Silva, Felipe das Neves Roque, Alves, José Luis Drummond, Cataldi, Marcio
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-01-2019; Springer; Springer Nature B.V
• Subjects: Accounting; Analysis; Bias; Boundary conditions; Calibration; Climate; Climate models; Climatology; Computer simulation; Data processing; Earth and Environmental Science; Earth Sciences; Geophysics/Geodesy; Global climate; Hydraulic flow; Hydroelectric plants; Hydroelectric power; Hydroelectric power plants; Hydrologic data; Hydrologic models; Hydrology; Inflow; Oceanography; Precipitation variability; Rain; Rainfall data; Rainfall runoff; Rainfall simulators; Rainfall-runoff modeling; Rainfall-runoff relationships; Regional climates; Removal; River basins; Rivers; Runoff; Simulated rainfall; Simulation; Soil; Soil moisture; Statistical methods; Statistics; Variability; Water cycle; Water inflow; South America; Bias correction; Global climate model; Hydrological model; Hydrometeorological modeling; Regional climate model; RegCM; SMAP
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-018-4166-7

This paper aims to validate inflow simulations concerning the present-day climate at Água Vermelha Hydroelectric Plant (AVHP—located on the Grande River Basin) based on the Soil Moisture Accounting Procedure (SMAP) hydrological model. In order to provide rainfall data to the SMAP model, the RegCM regional climate model was also used working with boundary conditions from the MIROC model. Initially, present-day climate simulation performed by RegCM model was analyzed. It was found that, in terms of rainfall, the model was able to simulate the main patterns observed over South America. A bias correction technique was also used and it was essential to reduce mistakes related to rainfall simulation. Comparison between rainfall simulations from RegCM and MIROC showed improvements when the dynamical downscaling was performed. Then, SMAP, a rainfall-runoff hydrological model, was used to simulate inflows at Água Vermelha Hydroelectric Plant. After calibration with observed rainfall, SMAP simulations were evaluated in two different periods from the one used in calibration. During calibration, SMAP captures the inflow variability observed at AVHP. During validation periods, the hydrological model obtained better results and statistics with observed rainfall. However, in spite of some discrepancies, the use of simulated rainfall without bias correction captured the interannual flow variability. However, the use of bias removal in the simulated rainfall performed by RegCM brought significant improvements to the simulation of natural inflows performed by SMAP. Not only the curve of simulated inflow became more similar to the observed inflow, but also the statistics improved their values. Improvements were also noticed in the inflow simulation when the rainfall was provided by the regional climate model compared to the global model. In general, results obtained so far prove that there was an added value in rainfall when regional climate model was compared to global climate model and that data from regional models must be bias-corrected so as to improve their results.