Browsing by Author "Ayes Rivera, Irma"
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Item Open Access Decline of fine suspended sediments in the Madeira River Basin (2003–2017)(MDPI, 2019-03-12) Ayes Rivera, Irma; Armijos Cardenas, Elisa Natalia; Espinoza Villar, Raúl Arnaldo; Espinoza, Jhan Carlo; Molina-Carpio, Jorge; Max Ayala, José; Gutierrez Cori, Omar; Martinez, Jean-Michel; Filizola, NazianoThe Madeira River is the second largest Amazon tributary, contributing up to 50% of the Amazon River’s sediment load. The Madeira has significant hydropower potential, which has started to be used by the Madeira Hydroelectric Complex (MHC), with two large dams along the middle stretch of the river. In this study, fine suspended sediment concentration (FSC) data were assessed downstream of the MHC at the Porto Velho gauging station and at the outlet of each tributary (Beni and Mamoré Rivers, upstream from the MHC), from 2003 to 2017. When comparing the pre-MHC (2003–2008) and post-MHC (2015–2017) periods, a 36% decrease in FSC was observed in the Beni River during the peak months of sediment load (December–March). At Porto Velho, a reduction of 30% was found, which responds to the Upper Madeira Basin and hydroelectric regulation. Concerning water discharge, no significant change occurred, indicating that a lower peak FSC cannot be explained by changes in the peak discharge months. However, lower FSCs are associated with a downward break in the overall time series registered at the outlet of the major sediment supplier—the Beni River—during 2010.Item Open Access On the relationship between suspended sediment concentration, rainfall variability and groundwater: an empirical and probabilistic analysis for the Andean Beni River, Bolivia (2003–2016)(MDPI, 2019-11) Ayes Rivera, Irma; Callau Poduje, Ana Claudia; Molina-Carpio, Jorge; Ayala, José Max; Armijos Cardenas, Elisa Natalia; Espinoza-Villar, Raúl; Espinoza, Jhan Carlo; Gutierrez-Cori, Omar; Filizola, NazianoFluvial sediment dynamics plays a key role in the Amazonian environment, with most of the sediments originating in the Andes. The Madeira River, the second largest tributary of the Amazon River, contributes up to 50% of its sediment discharge to the Atlantic Ocean, most of it provided by the Andean part of the Madeira basin, in particular the Beni River. In this study, we assessed the rainfall (R)-surface suspended sediment concentration (SSSC) and discharge (Q)-SSSC relationship at the Rurrenabaque station (200 m a.s.l.) in the Beni Andean piedmont (Bolivia). We started by showing how the R and Q relationship varies throughout the hydrological year (September to August), describing a counter-clockwise hysteresis, and went on to evaluate the R–SSSC and Q–SSSC relationships. Although no marked hysteresis is observed in the first case, a clockwise hysteresis is described in the second. In spite of this, the rating curve normally used ( SSSC=aQb ) shows a satisfactory R² = 0.73 (p < 0.05). With regard to water discharge components, a linear function relates the direct surface flow Qs–SSSC, and a hysteresis is observed in the relationship between the base flow Qb and SSSC. A higher base flow index (Qb/Q) is related to lower SSSC and vice versa. This article highlights the role of base flow on sediment dynamics and provides a method to analyze it through a seasonal empirical model combining the influence of both Qb and Qs, which could be employed in other watersheds. A probabilistic method to examine the SSSC relationship with R and Q is also proposed.