Maud Demarty

• Ph.D
• Consultant at Aqua-consult

The hydrological processes of cascading hydroelectric reservoirs differ from those of lakes, due to the importance of the inflows and outflows that vary with energy demand. These heat and water advection terms are rarely considered in water body energy balance analyses even though reservoirs are common man-made infrastructures, especially in North...

Reliable measurement of greenhouse gas emissions from reservoirs is essential for estimating the carbon footprint of the hydropower industry. Among the different emission pathways, degassing downstream of the turbines and spillway is poorly documented mainly because of the safety stakes related to sampling up and downstream the power plants. The al...

The thermal regime of hydroelectric reservoirs differs from that of lakes, as it is influenced not only by natural inflows and outflows of energy, but also by management rules through regulated downstream constraints and more importantly the electric demand through turbine flows. These advection terms are rarely assessed for hydroelectric reservoir...

Comprehensive studies of the impact of hydropower on coastal environments are rare. This study examines the impact of commissioning the hydropower plants of the Romaine complex on the freshwater discharge of the Rivière Romaine near its estuary and on the Chenal de Mingan ecosystem in the summers of 2015, 2017 and 2019. Continuous temperature, sali...

The chemistry of mercury in freshwater systems, particularly man-made reservoirs, has received a great deal of attention owing to the high toxicity of the most common organic form, methylmercury. Although methylmercury bioaccumulation in reservoirs and natural lakes has been extensively studied at all latitudes, the fate of the different forms of m...

The emission of CO2 and CH4 by diffusion, bubbling and downstream was measured in ten reservoirs representative of the diversity of French hydropower reservoirs in 2016. In all reservoirs, higher fluxes were measured in summer than in spring and winter. Low fluxes were measured in alpine reservoirs as compared to run-of-the-river and storage reserv...

Hydro-Quebec is one of the largest electric power companies in North America. In the early 2000s, the international concern regarding the long-term contribution of freshwater reservoirs to atmospheric greenhouse gases (GHG), led Hydro-Quebec to launch extensive studies of the net reservoir GHG emissions; the most comprehensive is the one carried ou...

Eastmain 1 reservoir (James Bay area, Quebec, Canada) is a 600 km² boreal reservoir, created in November 2005 in the Eastmain River watershed. To increase the volume of water transiting in Eastmain 1 (EM 1), the Rupert River was diverted. Partial flooding of the Rupert diversion bays (RD) took place in 2009 and the flooding was completed in 2011. C...

Fluxes of carbon dioxide (CO2) and methane (CH4) from hydroelectric and water supply reservoirs are receiving increasing attention around the world with a number of research groups having undertaken measurements of these emissions across a range of lakes and reservoirs located in different climates and landscapes. The use of floating chambers (aka...

In the present study, we measured independently CH4 ebullition and diffusion in the footprint of an eddy covariance system (EC) measuring CH4 emissions in the Nam Theun 2 Reservoir, a recently impounded (2008) subtropical hydroelectric reservoir located in Lao People Democratic Republic (PDR), southeast Asia. The EC fluxes were very consistent with...

In the present study, we measured CH4 ebullition and diffusion with funnels and floating chambers in the footprint of an eddy-covariance system measuring CH4 emissions at high frequency (30 mn) in the Nam Theun 2 Reservoir, a recently impounded (in 2008) subtropical hydroelectric reservoir located in Lao PDR, southeast Asia. The EC fluxes were very...

Carbon dioxide (CO2) and methane (CH4) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs...

Hydroelectric reservoirs have globally been identified as a significant source of methane (CH4) to the atmosphere, especially in the tropics. Assessing these emissions and their variations at small and large time scale represent important scientific challenges. In this context, the objectives of this work are (i) to compare different methodologies...

We present here the first comprehensive assessment of the carbon (C) footprint associated with the creation of a boreal hydroelectric reservoir (Eastmain-1 in northern Québec, Canada). This is the result of a large-scale, interdisciplinary study that spanned over a 7-years period (2003-2009), where we quantified the major C gas (CO2 and CH 4) sourc...

Greenhouse gas (GHG) emissions from reservoirs have been under the microscope for more a decade now. In particular, the high CH4 emissions reported in warm systems have tarnished the green credentials of hydroelectricity in terms of GHG emissions. Reliable estimates of CH4 emissions are crucial, since CH4 has a greenhouse warming potential of 25 an...

Surface water pCO2 and pCH4 measurements were taken in the boreal zone of Québec, Canada, from summer 2006 to summer 2008 in Eastmain 1 reservoir and two nearby lakes. The goal of this follow-up was to evaluate annual greenhouse gas (GHG) emissions, including spring emissions (N.B. gross emissions for reservoir), through flux calculations using the...

Canada has much potential to increase its already large use of hydroelectricity for energy production. However, hydroelectricity production in many cases requires the creation of reservoirs that inundate terrestrial ecosystems. While it has been reasonably well established that reservoirs emit GHGs, it has not been established what the net differen...

Surface water pCO2 and pCH4 measurements were made in Québec (Canada) during consecutive seasons from 2006 to 2008 in two boreal reservoirs and nearby lakes. The goal of this follow-up was to evaluate greenhouse gas emissions from the water bodies studied, through flux calculations using the Thin Boundary Layer Model. Our measurements underscored t...

Growing concern over the contribution of freshwater reservoirs to increases in atmospheric greenhouse gas (GHG) concentrations and the relevance of long-term continuous measurements has led Fisheries and Oceans Canada, in conjunction with Manitoba Hydro, to develop continuous GHG monitors. Continuous water pCO(2), pCH(4), and pO(2) measurements wer...

We studied the in situ release of dissolved organic carbon (DOC) by growing a submerged freshwater macrophyteepiphyte complex. Incubations with benthic chambers in five southeastern Quebec lakes show a net DOC production for different communities of Myriophyllum spicatum and Potamogeton spp. Daytime DOC release rates range from undetectable to 9.7m...

Questioning the possible implication of submerged macrophytes in carbon pool of lakes, we focus our research on the role of DOC release by macrophyte-epiphyte communities and more particularly on the factors influencing DOC release, considering the hypothesis of the « Overflow mechanism ». The objectives of the first chapter are (1) to measure the...

The results of dissolved GHG (CO2 and CH4) measurement campaigns carried out in Quebec (Canada) during the open-water periods and under-ice in a newly created reservoir (Eastmain 1), a 25 year old reservoir (Robert-Bourassa) and in three reference lakes are presented. While CO2 partial pressures varied with season with a net increase under the ice...

Growing concern regarding the contribution of freshwater reservoirs to the increase of atmospheric GHG added to the relevance of long term continuous measurements led Fisheries and Oceans Canada in conjunction with Manitoba Hydro to develop the continuous GHG monitor. Automated monitors were installed in the hydroelectric generating stations associ...

Understanding the survival, multiplication, and transmission to seeds of plant pathogenic bacteria is central to study their pathogenesis. We hypothesized that the type III secretion system (T3SS), encoded by hrp genes, could have a role in host colonization by plant pathogenic bacteria. The seed-borne pathogen Xanthomonas fuscans subsp. fuscans ca...

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