Simulating Discharge in a Non-Dammed River of Southeastern South America Using SWAT Model

Thais Fujita,Sameh Adib Abou Rafee,Marilia Moreira De Eiras,Rodrigo Augusto Ferreira De Souza,Marcos Vinicius Bueno De Morais,Eliane Barbosa Santos,Edmilson Dias De Freitas,Jorge Alberto Martins,Ana Carolina Freitas Xavier,Vanessa Cristina Dos Santos,Cintia Bertacchi Uvo,Anderson Paulo Rudke,Leila Droprinchinski Martins

doi:10.3390/w14030488

Abstract

Within a single region, it is possible to identify opposite changes in flow production. This proved to be the case for several basins in southeastern South America. It remains challenging to the causes this behavior and whether changes in streamflow will continue at current levels or decline in the coming decades. In this study, we used the Soil Water Assessment Tool to simulate monthly river discharge in the Ivaí River Basin, an unregulated medium-sized catchment and tributary of the Upper Paraná River Basin. After calibration, the simulated flow regime for the five streamflow stations based on the Nash-Sutcliffe Efficiency index (NSE) rated four of the streamflow stations Very Good (NSE between 0.86 and 0.89) and only one in the Good index (0.70). The overall flow behavior was well represented, although an underestimation was identified in four monitoring stations. Through assessment of its functionality and limitations in terms of specific flow duration curves percentages, the calibrated model could provide (to managers) the reliability needed for a realistic intervention. The results of this study may assist managers and support public policies for the use of water resources at the Ivaí River basin.

Highlights

Brazil is among the countries with the highest volume of freshwater in the world, and the available water is estimated to be around 78,600 m3/s [1]
In the well-established hydrological model Soil Water Assessment Tool (SWAT) Literature Database (https://www.card.iastate.edu/swat_articles/), we found 149 peer-reviewed studies pertaining to Brazilian territories, of which 53 were located within the Upper Paraná River Basin (UPRB)
Our analyses supported the position that the totality of information should be handed over to managers, and where it should be used sparingly

Summary

Introduction

Brazil is among the countries with the highest volume of freshwater in the world, and the available water is estimated to be around 78,600 m3/s [1]. Single governance is not effective when based on administrative and political boundaries In this sense, the river basin, as a unit of water resources management, was adopted in 1997 after the promulgation of the National Water Law (n◦ 9.344/97). The National Water Resources Policy (NWRP) was approved in its final form only in 2006 It was only recently approved, the NWRP considers national geographical, social, and economic diversity through region and user sector, employing decentralized planning. Still, it did not reach the entire Brazilian territory. The water scarcity affected water supply systems in the northern portion of the Upper Paraná River Basin (UPRB), where the larger metropolitan areas, such as São Paulo and Rio de Janeiro, are placed. The water crisis created strong disputes between industrial hubs and populations regarding water use, forcing extreme measures such as the pumping of dead storage reservoirs reserved for emergency use

Results

Discussion

Conclusion