HYDROLOGICAL ANALYSIS AND IMPACTS OF LAND USE AND OCCUPATION IN THE VERDE RIVER BASIN/MG: EVALUATION FROM THE GR4J MODEL

Abstract

The Rio Verde watershed, with an area of 6,891 km², is influenced by geological and climatic characteristics. Knowledge of the flow regime of the Rio Verde basin, located in the South/Southwest of Minas Gerais, is essential for agriculture, energy generation and drinking water supply. Data were collected from fluviometric and rainfall stations, highlighting the importance of integrating land use and hydrological behavior for more accurate hydrological forecasts. The GR4J hydrological model can be used to evaluate the rainfall-flow ratio in order to characterize and establish a variation about the water regime of a basin. The calibration of the model, carried out between 1989 and 1992, resulted in an NSE of 0.51, indicating a moderate ability to replicate the hydrological behavior, although with difficulties in capturing flow peaks. In the validation, from 1993 to 1994, the performance improved, with an NSE of 0.68 and a KGE of 0.84, demonstrating greater accuracy in the flow patterns. The analysis of land use in the 90's revealed the predominance of pastures, occupying about 29.8% of the area in 1991, which may have increased the surface runoff.