Land cover change explains the increasing discharge of the Paran\xe1 River

Eunjee Lee,Eunjee Lee,Eunjee Lee,Angela Livino,Angela Livino,Angela Livino,Ke Zhang,Ke Zhang,Paul Moorcroft,John Briscoe,John Briscoe,Jerson Kelman,Shin-Chan Han

doi:10.1007/s10113-018-1321-y

Abstract

Over the past 40 years, the discharge in South America’s Paraná River basin has increased despite no evidence of significant rainfall increases in the basin. In this analysis, we show that the observed multi-decadal increase in discharge can be explained by concomitant changes in land cover that have occurred within the basin during this period. Our analysis also indicates that the peak discharge timing may have shifted concurrently from January/February in the 1970s to March in more recent decades. While land-use effect dominantly alters the long-term temporal dynamics of the river discharge over multi-decades, the change in the seasonality of the discharge can be attributable to the combined effect of the land-use and climate variability. This study suggests that the mean annual discharge is likely to change in the other South American River basins where land transformation is currently taking place, and the shift of the month of peak discharge needs to be taken into consideration to forecast the hydropower generation under changing climate and land conversion.

Highlights

Hosting multiple hydropower dams that generate a significant portion of electricity to meet the regional demand in southern Brazil, the Paraná River basin is geographically and economically important
We examined the mechanistic linkages between climate variability, land-use, and resulting river discharge in the Paraná River basin using a terrestrial biosphere model, the Ecosystem Demography version 2 (ED2) (Moorcroft et al 2001; Albani et al 2006; Medvigy et al 2009)
The ED2 model of this study is shown to reproduce reasonably well the observed discharge increase at Itaipu and the regional total water storage (TWS) derived by Gravity Recovery and Climate Experiment (GRACE) satellite measurement

Summary

Introduction

Hosting multiple hydropower dams that generate a significant portion of electricity to meet the regional demand in southern Brazil, the Paraná River basin is geographically and economically important. The famous Itaipu hydropower plant, built in the lower reaches of the upper Paraná River basin at the BrazilParaguay border, has the installed capacity of 14,000 MW (MW), yielding the electricity that supplies 15% of Brazil’s total energy consumption (https://www.itaipu.gov.br/en). Having the 1970s as the baseline period, the reconstructed natural flow inferred from the measurements from the gauge station at the Itaipu dam (25.43 S, 54.59 W) affirms the trend: + 11.1% in the 1980s, + 18.0% in the 1990s, and + 6.3% in the 2000s The baseline precipitation of the 1970s, from the combination of reanalysis and observation-based datasets (Sheffield et al 2006), indicates that mean annual rainfall decreased by 1.5% in the 1980s (or by 5.0% excluding the rainfall of the 1983 flood event as an outlier), increased by 4.2% in the 1990s, and declined slightly by 1.0% in the 2000s

Methods

Results

Discussion

Conclusion