Influence of rainfall recharge on suspended sediment yields in the Piracicaba drainage basin in southeastern Brazil

ABSTRACT

A study on fine-suspended sediment (FSS) yield dynamics was performed in the Piracicaba River drainage basin in the state of São Paulo, Brazil, during an entire hydrological year, and a set of nine flood hydrographs that encompass wet and dry seasons were analysed. The average-specific sediment transport was 88 t km⁻² y⁻¹. Hydrograph analysis verified that the lowest sediment yield, totalling 313 t, was related to the driest season of the hydrological year; whereas, the highest yield, amounting to 196,000 t, was related to the season of heaviest rainfall. Both unit hydrographs lasted 10 consecutive days, yet they were obtained under adverse hydrological conditions, with accumulated precipitation in the dry and wet seasons of 14 and 319 mm, respectively, which likely gave rise to different soil saturation levels and changes in surface runoff. This increase in FSS yield, which is greater than 600-fold, is possibly related not only to the different hydrological conditions, but also to the use and occupation of the soil in this agricultural region, where over 70% of the surface area is dedicated to growing pastures and sugar cane.

KEYWORDS:

• Fine-suspended sediment
• particulate load
• rainfall recharge
• Piracicaba River

Acknowledgements

The authors wish to thank the Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP) for financial support and fellowship.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Diego Vendramini http://orcid.org/0000-0003-4304-8111

Additional information

Funding

This work was supported by the São Paulo Research Foundation (FAPESP) under [Grant 2010/00133-2].