Application of a three-dimensional hydrodynamic model to the Nam Theun 2 Reservoir (Lao PDR)

Chanudet, Vincent; Fabre, Violaine; Kaaij, T. van der

doi:10.1016/j.jglr.2012.01.008

Cited by 48 publications

(58 citation statements)

References 21 publications

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“…2) and potentially decreases to a minimum of 86 km² at the end of the dry season. The reservoir is relatively shallow with an average depth of 8 m (Chanudet et al, 2012). The main tributaries of the reservoir are the Nam Xot, the Nam Theun and the Nam On Rivers.…”

Section: Study Areamentioning

confidence: 99%

Fish population dynamic in the newly impounded Nam Theun 2 Reservoir (Lao PDR)

Cottet

Descloux²,

Guédant

et al. 2015

Hydroécol. Appl.

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-A fish population monitoring was carried out in the reservoir and tributaries of the hydropower project Nam Theun 2 (Lao PDR) at the end of the warm and dry seasons and at the end of the warm and wet seasons between 2008 and 2013. The study focused on three aquatic systems (river upstream, transition area, and reservoir) and different drowned habitats (dense/light forests and agricultural soils) associated or not with the presence of villages. The reservoir fish population was expected to follow three distinct phases, which should be respectively a rapid increase in biomass and abundance (trophic upsurge) followed by a decline and a stabilization of the population. This succession appeared to be different to the commonly observed scenario in terms of biomass, abundance and taxonomic richness compared to other temperate and tropical reservoirs. The indicator species (H. macrolepidota and P. carinatus) did not show changes in their size range since impoundment. The presence of structured habitats (e.g. inundated forest) favoured the fish population in terms of biomass and abundance. The fish population in the transition area and the river upstream improved quickly after the impoundment and presented higher taxonomic richness compared to the reservoir. Finally, the transition area appeared to be the most productive area within the Nam Theun 2 Reservoir especially if it remained outside of fishing activities. Key words -fish population, impoundment, neotropical reservoir, habitatsRésumé -Un suivi des populations piscicoles a été réalisé au sein du réservoir hydro-élec-trique de Nam Theun 2 (Laos) et de ses affluents à la fin de la saison chaude et sèche et à la fin de la saison chaude et humide de 2008 à 2013. Trois systèmes aquatiques ont été étu-diés (rivière amont, zone de transition et réservoir) ainsi que différents habitats inondés (forêt dense/clairsemée, sols agricoles) associés ou non à la présence de villages. Il était attendu

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Section: Study Areamentioning

confidence: 99%

Fish population dynamic in the newly impounded Nam Theun 2 Reservoir (Lao PDR)

Cottet

Descloux²,

Guédant

et al. 2015

Hydroécol. Appl.

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“…Complete overturn was observed every year during the CD season (mid-October to mid-February) any time from late November to late January Chanudet et al, 2012). Temperature was then constant with depth for periods of a few days or weeks in some of the sampling stations.…”

Section: Vertical Profiles and Surface Concentrationsmentioning

confidence: 97%

“…Based on the physical modelling by Chanudet et al (2012), an area of~3 km 2 all year long (i.e. whatever the water level in the reservoir) was attributed to the specific diffusive fluxes found in RES9.…”

Section: Diffusive Fluxes From the Reservoirmentioning

confidence: 99%

Nam Theun 2 Reservoir four years after commissioning: significance of drawdown methane emissions and other pathways

et al. 2016

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-Hydro-reservoirs are recognized as potentially significant emitters of methane at the global scale. However, there are still large uncertainties in estimating such emissions at this scale due to the lack of comprehensive measurements of methane emissions in a wide range of climatic zones, for hydro-reservoirs with variable characteristics, and including all emissions pathways. This study presents an assessment of methane emissions for the 2013 year, that is four years after commissioning, for the Nam Theun 2 hydro-system, a 489 km² subtropical reservoir with a large drawdown area. All of the major pathways have been computed here, i.e., ebullition, diffusion, degassing, emissions from the drawdown area, and diffusion from downstream, and included in an emission budget. Emissions from the upstream area strongly dominate when compared to the downstream ones, a feature quite specific to the Nam Theun 2 reservoir. The drawdown area and the emissions by diffusion downstream represented a small contribution to the total emissions. About half of the methane is emitted during the four months of the warm dry season (from mid-February to Mid-June). Total methane emissions in NT2 have decreased from 35.6±2.6 Gg(CH 4 ) year -1 in 2010 to 24.5±1.5 Gg(CH 4 ) year -1 in 2013 though this difference was not found to be quite statistically significant.

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“…The reservoir flooded almost 70% of dense to light forest, 23% of degraded forest, riparian forest and agricultural soils and the last 7% were composed of water system, swamps and villages (Descloux et al, 2011). The reservoir is qualified as a dendritic and is relatively shallow with an average depth of 8 m (Chanudet et al, 2012). The main tributaries of the reservoir are the Nam Xot, the Nam Theun and the Nam On Rivers.…”

Section: Study Areamentioning

confidence: 99%

5 years of monitoring of zooplankton community dynamics in a newly impounded sub-tropical reservoir in Southeast Asia (Nam Theun 2, Lao PDR)

Descloux¹,

Cottet

2016

Hydroécol. Appl.

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5 years of monitoring of zooplankton community dynamics in a newly impounded sub-tropical reservoir in Southeast Asia (Nam Theun 2, Lao PDR) Abstract -The zooplanktonic community of the Nam Theun 2 Reservoir, newly impounded, located in Lao PDR was monitored from 2009 to 2013. Five sampling stations distributed on the surface of the reservoir were sampled on a monthly basis. Results were interpreted to assess the spatial and temporal variability of the communities and to identify environmental factors such as physical or water chemical parameters influencing communities. The zooplanktonic community was dominated by Copepods over the study period and was characterized by low densities and biomasses reflecting low productivity conditions. The spatial heterogeneity of the zooplanktonic community observed along a longitudinal gradient disappeared rapidly after the beginning of the operational phase in 2010 and tended to stabilize. The results also highlighted a seasonal variability explained by a phytoplankton-based food chain. Zooplankton communities were significantly and negatively driven by hydraulic factors, such as the mixing period, or water quality factors, such as water temperature or the depth of the oxycline. This zooplankton community must be evaluated in order to anticipate the food availability for zooplanktivorous fish before developing a fish management plan.Key words -sub-tropical reservoir, Southeast Asia, Copepods, spatial heterogeneity, mixing

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Application of a three-dimensional hydrodynamic model to the Nam Theun 2 Reservoir (Lao PDR)

Cited by 48 publications

References 21 publications

Fish population dynamic in the newly impounded Nam Theun 2 Reservoir (Lao PDR)

Fish population dynamic in the newly impounded Nam Theun 2 Reservoir (Lao PDR)

Nam Theun 2 Reservoir four years after commissioning: significance of drawdown methane emissions and other pathways

5 years of monitoring of zooplankton community dynamics in a newly impounded sub-tropical reservoir in Southeast Asia (Nam Theun 2, Lao PDR)

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