Hydro-physical processes at the plunge point: an analysis using satellite and in situ data

Assireu, Arcilan Trevenzoli; Alcântara, Enner; Novo, Evlyn Márcia Leão de Moraes; Roland, Fábio; Pacheco, F.; Stech, José; Lorenzzetti, João A.

doi:10.5194/hess-15-3689-2011

Cited by 13 publications

(11 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, sporadic heavy rain may occur in the region, mixing the entire water column of the reservoir. Studies made in the Manso reservoir during the same period of our sampling (Assireu et al, 2011; Pacheco et al, 2011) reported a plunge inflow of the river Manso in the reservoir, allocating the river at the hypolimnion level. This inflow of the Manso River in the reservoir highlights possible interactions between the river water and the POM pools in hypolimnion of the dam zone.…”

Section: Discussionmentioning

confidence: 56%

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir

Cardoso¹,

Vidal²,

Mendonça³

et al. 2013

Front. Microbiol.

View full text Add to dashboard Cite

Substantial amounts of organic matter (OM) from terrestrial ecosystems are buried as sediments in inland waters. It is still unclear to what extent this OM constitutes a sink of carbon, and how much of it is returned to the atmosphere upon mineralization to carbon dioxide (CO2). The construction of reservoirs affects the carbon cycle by increasing OM sedimentation at the regional scale. In this study we determine the OM mineralization in the sediment of three zones (river, transition, and dam) of a tropical hydroelectric reservoir in Brazil as well as identify the composition of the carbon pool available for mineralization. We measured sediment organic carbon mineralization rates and related them to the composition of the OM, bacterial abundance and pCO2 of the surface water of the reservoir. Terrestrial OM was an important substrate for the mineralization. In the river and transition zones most of the OM was allochthonous (56 and 48%, respectively) while the dam zone had the lowest allochthonous contribution (7%). The highest mineralization rates were found in the transition zone (154.80 ± 33.50 mg C m-2 d-1) and the lowest in the dam (51.60 ± 26.80 mg C m-2 d-1). Moreover, mineralization rates were significantly related to bacterial abundance (r2 = 0.50, p < 0.001) and pCO2 in the surface water of the reservoir (r2 = 0.73, p < 0.001). The results indicate that allochthonous OM has different contributions to sediment mineralization in the three zones of the reservoir. Further, the sediment mineralization, mediated by heterotrophic bacteria metabolism, significantly contributes to CO2 supersaturation in the water column, resulting in higher pCO2 in the river and transition zones in comparison with the dam zone, affecting greenhouse gas emission estimations from hydroelectric reservoirs.

show abstract

Section: Discussionmentioning

confidence: 56%

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir

Cardoso¹,

Vidal²,

Mendonça³

et al. 2013

Front. Microbiol.

View full text Add to dashboard Cite

show abstract

“…During the rainy season in the Funil Reservoir, due to the substantial difference between the river and reservoir surface temperatures (∼ 4 • C), the river water progressively sinks down (underflow) and contributes to the thermal stability of the water column (Fig. 5a, Assireu et al, 2011). The denser river water flows under the lighter reservoir water and waves and billows develop along the interface due to the shear velocity.…”

Section: Physical Features and Spatial Distributionmentioning

confidence: 99%

The effects of river inflow and retention time on the spatial heterogeneity of chlorophyll and water–air CO<sub>2</sub> fluxes in a tropical hydropower reservoir

et al. 2015

Self Cite

View full text Add to dashboard Cite

Abstract. Abundant research has been devoted to understanding the complexity of the biogeochemical and physical processes that are responsible for greenhouse gas (GHG) emissions from hydropower reservoirs. These systems may have spatially complex and heterogeneous GHG emissions due to flooded biomass, river inflows, primary production and dam operation. In this study, we investigated the relationships between the water-air CO 2 fluxes and the phytoplanktonic biomass in the Funil Reservoir, which is an old, stratified tropical reservoir that exhibits intense phytoplankton blooms and a low partial pressure of CO 2 (pCO 2 ). Our results indicated that the seasonal and spatial variability of chlorophyll concentrations (Chl) and pCO 2 in the Funil Reservoir are related more to changes in the river inflow over the year than to environmental factors such as air temperature and solar radiation. Field data and hydrodynamic simulations revealed that river inflow contributes to increased heterogeneity during the dry season due to variations in the reservoir retention time and river temperature. Contradictory conclusions could be drawn if only temporal data collected near the dam were considered without spatial data to represent CO 2 fluxes throughout the reservoir. During periods of high retention, the average CO 2 fluxes were 10.3 mmol m −2 d −1 based on temporal data near the dam versus −7.2 mmol m −2 d −1 with spatial data from along the reservoir surface. In this case, the use of solely temporal data to calculate CO 2 fluxes results in the reservoir acting as a CO 2 source rather than a sink. This finding suggests that the lack of spatial data in reservoir C budget calculations can affect regional and global estimates. Our results support the idea that the Funil Reservoir is a dynamic system where the hydrodynamics represented by changes in the river inflow and retention time are potentially a more important force driving both the Chl and pCO 2 spatial variability than the in-system ecological factors.

show abstract

“…The inflow water with sediments, was heavier and colder than the reservoir water, thus it plunged into the water column in reservoir and became an 25 underflow (turbid flow). The reservoir surface was less affected by the underflow and maintained a relatively stable emission rate (F. as continued water discharging allowed little time for mineralization of organic carbon (Assireu et al, 2011;Senturk, 1994). But in the dry season, the clean inflow water was lighter than the reservoir water, thus it joins the reservoir as surface flow.…”

Section: Damming Effect On Carbon Evasion In the Upper Mekong Rivermentioning

confidence: 99%

Physical-controlled CO<sub>2</sub> effluxes from reservoir surface in the upper Mekong River Basin: a case study in the Gongguoqiao Reservoir

Lin¹,

Lu²,

Liu³

et al. 2018

Preprint

View full text Add to dashboard Cite

Abstract. Impounding has greatly altered carbon cycle in rivers. To quantify this effect, we measured CO2 effluxes from a mountainous valley-type reservoir in the upper Mekong River (Lancang River in China) and compared with those from the pristine river channel. Evasion rates from reservoir surface was 408 mg m rainy season deviated from the traditional theory that rainfalls can bring more organic carbon for mineralization and increase the efflux. The analysis found that efflux was closely related to the physical mixing process of inflow and reservoir water. The light overflow rich in CO2 in dry season contact the atmosphere directly and release more gases while the underflow in warm wet season leaved insufficient time for mineralization and hardly support high efflux in surface water. Evasion rate at the downstream of the dam was also limited due to surface water withdrawal. Lastly, the littoral zone was found to be a hotspot 20 for CO2 emission despite its limited area leading to its negligible contribution in total annual emission rate. In contrast, diurnal efflux variability in the littoral zone indicates that the effluxes were significantly higher at night than in the daytime, which increased the annual emission rate to by a half.

show abstract

Hydro-physical processes at the plunge point: an analysis using satellite and in situ data

Cited by 13 publications

References 46 publications

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir

The effects of river inflow and retention time on the spatial heterogeneity of chlorophyll and water–air CO<sub>2</sub> fluxes in a tropical hydropower reservoir

Physical-controlled CO<sub>2</sub> effluxes from reservoir surface in the upper Mekong River Basin: a case study in the Gongguoqiao Reservoir

Contact Info

Product

Resources

About

Hydro-physical processes at the plunge point: an analysis using satellite and in situ data

Cited by 13 publications

References 46 publications

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir

The effects of river inflow and retention time on the spatial heterogeneity of chlorophyll and water–air CO&lt;sub&gt;2&lt;/sub&gt; fluxes in a tropical hydropower reservoir

Physical-controlled CO&lt;sub&gt;2&lt;/sub&gt; effluxes from reservoir surface in the upper Mekong River Basin: a case study in the Gongguoqiao Reservoir

Contact Info

Product

Resources

About

The effects of river inflow and retention time on the spatial heterogeneity of chlorophyll and water–air CO<sub>2</sub> fluxes in a tropical hydropower reservoir

Physical-controlled CO<sub>2</sub> effluxes from reservoir surface in the upper Mekong River Basin: a case study in the Gongguoqiao Reservoir