A resposta da dinâmica sedimentar dos rios Xingu e Tapajós às mudanças climáticas e barragens de usinas

hidrelétricas: riscos para conservação da biodiversidade e produção de energia na Amazônia

Processo 2016/02656-9

Coordenador: André Oliveira Sawakuchi (IGc-USP)andreos@usp.br

The Xingu and Tapajós Rivers

Mazoca (2017)

Tapajós

Xingu

Photos: Leandro Sousa and Mark Sabaj

High diversity of lithophilic andrheophilic fishes

The largest tropical-rapidsecosystem

Hydropower dams in the Amazon

Latrubesse et al. (2017 – Nature)

São Luiz do Tapajós ~6,350 MWBelo Monte ~11,230 MW

Water balance projections (2070-2099) Xingu and Tapajós watersheds-35% Runoff

Sorribas et al. (2016 – Climatic Change)

Aquatic and flooding forest ecosystems

Changes in water column andsubstrates

Habitat loss and fragmentation

Fluvial system

Water balance Sedimentation/erosion dynamics

Climate and anthropogenic changes

Precipitation Hydropower dams

Approach: from past to present and future

Millenial tomultidecadalhydroclimate andlandscape changes

Variability of themodern system

Future scenarios

Middle and Late HoloceneLast 7,000 years

1970-2018

2018-2100

Results – Sept 2017 – Jun 2018 (Xingu)

Imagem: Juan Doblas (ISA)

Volta Grande do XinguUHE Belo Monte

Author: Marcelo Camargo (2016)

Millenial changes in hydroclimate

Xin

gu

Amazon

Sediment core

Bertassoli et al. (in prep.)

Precip in E Amazon (Wang et al., 2017 – Nature)

Water/sediment discharge

Decreasing water discharge since 2 kaMultidecadal abrupt changes in precip and water discharge

Slightly acid shallow water, lownutrients concentration (Staurosira,

Stauroneis, Staurosirella, Pinnularia, Gomphonema)

Years BP

Turbulent water(Aulacoseira)

Diatom analysisSamantha Borges (DR)Krysna Ferreira (MS)

Hydroclimate and landscapechanges

Flooding forest areas expanded after 5 kaHigh rate of expansion after 1 ka in the Xingu

OSL and 14C ages of flooding forest substrates in Amazon

Pupim et al. (in prep.)

10 km

Terra FirmeIgapó

Terra Firme

1.1±0.1 ka – present

Hydroclimate and vegetationchanges

Concentration (grains/cm3)

Core XC06

Pollen and charcoal analyses – Rudney Santos (DR)

Charcoal in sediments

Pollens and spores

• Cecropia, a successional forest indicator, is presentin expressive quantities, suggesting that the vegetation has not reached a climax stage since the Mid Holocene

• Mauritia flexuosa (Buriti palm) may be related to Late Holocene anthropogenic action

• Coarser charcoal particlessuggest increase of local firesduring the Late Holocene

Beach

River bed

Sites for P. expansa nesting (Tartaruga-da-Amazônia)

Pimental Dam

• Coarse sand (0.5-1.0 mm) is the major material for beach development• Sand sources are located upstream the dams• Upstream trapping of coarse sand reduce beach resilience

Luana Ferreira de Jesus (MS)

Projection: habitat loss (P. expansa)

After UHE Belo Monte

Lithophilic fish – Baryancistrus xanthellus

Magalhães et al. (in prep.)

• Average suspended sed rate at the Xingu ria = 0.35 cm/year(Bertassoli et al., 2017)

Population expansionstarted at 200 ka

Shift from bedrock to mudsubstrates (~80 km) in decadaltimescale

Carbon balance under the UHE Belo Monte

CO2 and CH4 sources

Flooded vegetation(forest and pasture)

Deposition of organicsediments

Rate of carbon accumulationFrom 84 g m-2 yr-1 to 169 g m-2 yr-1

TOC = 2-3%

• Higher production of CH4 and CO2 in flooded pasture soils

• Emissions concentrated in the first years after damming

Sawakuchi, H.O. et al. (in prep.)

The Xingu under future climate

Simulation of future waterdischarge at Belo Monte

Camargo et al. (in prep.)

• Higher frequency of droughts for the period 2017-2045 (CMIP5/IPCC, RCP 8.5 scenario);

• Future water discharge 28% lower than the observed during1990-2015

Camargo et al. (in prep.)

Monthly precip anomalies 2017-2045 (mm)

Present (1990-2015) and future (2017-204) water discharge (m3/s)

Energy generation: lower thanprojected?

Energy generation versus wateravailable for downstreamecosystems

Obrigado!

...Tapajós

Xingu...