CLIQUEZ POUR AJOUTER UN TITRE - MONITORING MINING IMPACTS ON WATER QUALITY AND RIVER MORPHOLOGY IN FRENCH GUYANA - HYBAM
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Monitoring mining impacts on water quality
and river morphology
in French Guyana
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Marjoriepour
Cliquez Gallay
ajouter
PhD un sous-titre
Environmental Sciences: Hydrology and Hydrochemistry
Université de Guyane française
4th of September 2019
8th HYBAM INTERNATIONAL CONFERENCE
Titre de la présentation
Context
1. LOCATION
Guiana Shield (1500 000 km²)
Amazon to the Orinoco
Main source of freshwater
Rich in minerals
Biodiversity hotspots
2 networks :
HYBAM = since 2004
DCE = good quality of water
(ecology, chemistry,
morphology) since 2007
Figure. Dry and Raining season in French Guiana
2 8th HYBAM INTERNATIONAL CONFERENCE
Context
1. MINING ACTIVITIES DEVELOPMENT
• Increase of deforestation for gold mining
41%
9%
28 % 11%
Figure. Deforestation for mining (Alvarez-Berríos and
Aide, 2015).
• since 2000, mining surfaces degrades
Figure. Linear of river kilometers impacted by legal
water quality and river system morphology and illegal mining (ONF, 2016)
3 8th HYBAM INTERNATIONAL CONFERENCE
Context
Introduction
1. LEGAL ACTIVITIES PHASES
Fig. Initial river Fig. Deforestation and calibration Fig. Mechanical crushing
of the initial river
Fig. Small scale mining floating
boat in the Maroni River
Fig. Settling tanks Fig. Positioning of woods and
revegetalisation
4 8th HYBAM INTERNATIONAL CONFERENCE
Main research questions
impacts due to anthropic activities
Are there any significant
as deforestation and gold mining in medium catchments as
the Maroni and Oyapock :
Part 1 : on turbidity and TSS concentrations and fluxes ?
Part 2 : on POC, DOC, TOC, NP, Chl-a concentrations and fluxes ?
Part 3 : on Rare Earth Element (REE) concentrations and fluxes ?
NEW PROJECTS (2019-2022) in small catchments
Part 4 : on hydromorphology ? how to restore the hydrosystem after
mining ?
Part 5 : on turbidity evolution and clugging ?
5 8th HYBAM INTERNATIONAL CONFERENCE
PART 1
1. TSS discharge and water turbidity
1 monitoring (2000-2016)
of the Maroni and Oyapock rivers
with in situ data and MODIS captors
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Main question
Are there any significant impacts on TSS and turbidity fluxes in
the Maroni and Oyapock rivers, due to anthropic activities as
deforestation and mining ?
In Land Degradation and Development (2018)
7 8th HYBAM INTERNATIONAL CONFERENCE
Study sites
• BV Maroni : 57% Surinam / Station LT : Langa Tabiki (91%), Station SH (en aval)
• BV Oyapock : 51% Brasil / Station SM : Saut Maripa (74%) Months
Discharge
SH
LT
SM
Discharge
Figure. Interannual
discharge at LT and SM.
Figure. Localisation of the Maroni and Oyapock catchments
(Adapted from Sondag et al., 2010).
8 8th HYBAM INTERNATIONAL CONFERENCE
Methods
• Measure of TSS and Rrs in-situ (TriOs RAMSES) at SM (berge) ;
RG
SH
RD
different time of the hydrological cycle
• Estimation of the MODIS Rrs (MOD3R software:
Martinez et al., 2009)
• Creation of the empirical relationship between TSS Figure. Maroni section at SH
and : Rrs in-situ & Rrs MODIS
• Comparision between in situ TSS and estimated TSS
(with MODIS)
• Calcul of bias, RMSE
• Calcul of sediment load (SL= Cj *Qm), specific load
(SY : t/km²/yr-1) and specific discharge (R : l/km2/yr-1) Figure. TriOs RAMSES
• Statistics : Mann-Kendall test (tendencies) ; de Pettitt’s (breakpoints) and
Spearman correlation (predictives parameters)
• Comparison of TSS tendencies with land degradation (agricultural, mining,
urban) and climate (P & R)
9 8th HYBAM INTERNATIONAL CONFERENCE
Turbidity TSS with MODIS TSS in situ Discharge
Main results
Breakpoint
1. MARONI BASSIN
TSS
Discharge
TSS
Breakpoint
Turbidity
TSS
Breakpoint
TSS
Turbidity
River
direction
Years
Figure. TSS MODIS from SH to MPS stations
Figure. MODIS virtual stations in the Maroni
and Turbidity at MPS station.
river
10 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. CUMULATIVE TRENDS
• Increase of TSS concentration & Change in the cumulative curves trends
MARONI OYAPOCK
OLIVAR SAUT MARIPA
SAUT HERMINA
5 t/km²/an SY = 9 - 41 t/km²/an SY = 8 - 19 t/km²/an
l/s/km² R = 22 – 44 l/s/km²
R = 16 – 43 l/s/km²
SY Cumulated Sediment Yield
R Cumulated Specific Runoff Cumulated Specific Runoff
Figure. Doble cumulative distribution : A) from 2001 to 2014 at CB
(Orinoco), B) from 1985 to 2015 at SH (Maroni), C) from 1989 to 2015 at SM
(Oyapock).
Inbalance Inbalance
11 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. CUMULATIVE TRENDS
• Increase of TSS concentration & Change in the cumulative curves trends
ORENOQUE
CIUDAD BOLIVAR In South American Earth Sciences(2019)
SY = 95 -125 t/km²/an
R = 31 – 47 l/s/km²
Cumulated Sediment Yield
Balance
SY
R Cumulated Specific Runoff
Figure. Doble cumulative distribution : from
2001 to 2014 at CB (Orinoco)
12 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. SPEARMAN RANK CORRELATION
• What is the relationship between TSS concentration & SY with
climatic parameters ?
Oyapock :
• explained at 82 % by R and Q
Maroni :
• explained at 61% and 57% by precipitations in
the upper Maroni (MPS & PPI)
• no relationship with R or Q
13 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. EXPLANATORIES AND PREDICTORS VARIABLES ?
• CLIMATE ?
Precipitation ? No change in mean, max, min trends (1978-2015).
Discharge ? No change in mean, max, min trends (1953-2015).
LAND USE ? Comparison between specific erosion and land use
Specific erosion Agricultural and artificials Mining surfaces
surfaces
R²= 0,97
SY
SY
Years Years
Figure. Comparison between specific erosion and agricultural, artificial and mining
surfaces in the Oyapock and Maroni catchment
14 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. MAIN SUBCATCHMENTS IMPACTED BY GOLD MINING
Figure. Evolution of
mining deforestation
surfaces A) per sub-
catchments in B) 256
2000, C) 2008, D)
2014 in percentage per
sub-catchment, in the
MAR and the OYA
catchments.
15 8th HYBAM INTERNATIONAL CONFERENCEPART 2
12. Fluxes of dissolved and particulate
carbone and nitrogen (2014-2016)
in the Maroni and Oyapock rivers
Cliquez pour ajouter un titre de sectionMain question
Are there any significant impacts of deforestation and mining
on POC, DOC, TOC, NP, Chl-a concentrations and fluxes in the
Maroni and Oyapock rivers?
In Hydrological processes (2018)
17 8th HYBAM INTERNATIONAL CONFERENCEMethods
• Water samples (2L) in-situ : concentration of carbone, particulate nitrogen, Chl-a (n ~ 140) in
TSS
Parameters Définition
TSS Total concentration (> 0.2 µm)
POC Fraction of particulate organic carbon (> 0.2 µm)
PN Fraction of particulate nitrogen (> 0.2 µm)
Chl-a Fraction of chlorophyll (> 0.2 µm )
DOC Dissolved carbon organic fraction (< 0.2 µm)
TOC Total carbon (POC + DOC)
Mineral part in the TSS
POC%TSS Fraction of particular carbon in TSS
PN%TSS Fraction of particular nitrogen in TSS
• High relation with : deforestation, agriculture, soil erosion, organic decomposition, bacterias,
eutrophication,… & They can be estimated with spatial sensors…
• Calcul of load (SL= Cj *Qm) and specific load (t/km²/yr-1)
18 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. MEAN CONCENTRATIONS (2014-2016)
• Similar for TOC, DOC, COP, PN, Chl-a, C/N and for TSS, %COP and %NP in TSS
TOC
DOC
Mean concentrations
POC
PN
Chl-a
TSS
POC/TSS (%)
PN/TSS (%)
• Good relation with TSS:
POC
PN
Oyapock Maroni
Relation
(SM) (SH)
POC and TSS 0.89 0.64
PN and TSS 0.61 0.45
TSS TSS
19 8th HYBAM INTERNATIONAL CONFERENCEMain results
1. ANNUAL AND SPECIFIC FLUXES (MARONI AND OYAPOCK)
Figure. Mean annual flux and
specific flux of the TOC, DOC, POC,
TOC PN and Chl-a in th Maroni (SH) and
Annual fluxes
DOC Oyapock (SM) rivers.
POC
PN
Chl-a
TOC
Specific fluxes
DOC
POC
PN
Chl-a
20 8th HYBAM INTERNATIONAL CONFERENCEPART 3
3. REE trends
1in the Maroni and the Oyapock rivers
Is there significant impacts of
land use on REE spatio-temporal
Cliquez pourand
concentrations ajouter
fluxes inun
thetitre de section
Maroni and Oyapock rivers ?
Actual study
Data from the HYBAM and DCE networks
(2008-2018)PART 4
1
4. Project RHYSOG
from 2019 to 2022
Cliquez pour ajouter un titre de sectionPART 5
5. Project COLMATAGE :
1 water turbidity and
clugging of small streams
due to gold mining activities
Project from 2020 to 2022
Cliquez pour ajouter un titre de sectionMain goals
Introduction
• Increase natural knowledges :
• Catchment forms (protocol :
Carhyce & Photogrammetry)
• TSS concentrations, fluxes &
deposition (protocol in construction) Fig. Morphology and water discharges measures
• Water discharge
• Disponibility in material (sediments
and woods)
• Increase exploitation knowledges :
Fig. Sediment traps Fig. Material disponibility
• Crossing rivers, roads and
revegetalisation
Restauration of small rivers Fig. Exploitation
• Propose technical recommandations for :
• Dimensioning the exploitation (river
slope, meanders, river width and
depth, settling tanks, scheduled
channel,… ) to encourage a return to
natural processes and decrease
sediment transport
24 8th HYBAM INTERNATIONAL CONFERENCE2 I THANK YOU FOR THE ATTENTION
MERCI
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