REVIEW OF GREENHOUSE GAS EMISSIONS FROM THE ...

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4. Information on sedimentation rates in reservoirs should be gathered together withestimates of the organic content in order to allow calculations of carbon sequestration insediments.5. Information on the stratification of reservoirs in India should be gathered. It is likely thatthe stratification differs between regions/states.6. Guidelines that allow proper consideration of the greenhouse effect should be produced toassist future environmental impact assessments.6
Annex 1: Predicting Emissions of Greenhouse Gases from Future Hydropower Projectsin the Middle Reaches of Sutlej River1.0 BackgroundTwo workshops hosted by UNESCO/IHA have analysed the scientific basis for estimatingemissions of greenhouse gases from freshwater reservoirs 1 . “With regards to the three speciesof gases of interest (N 2 O, CO 2 and CH 4 ), the participants concluded the following:• Data were presented on the recordings of N 2 O related to freshwater reservoirs ineach of the major climate types. Very small N 2 O emissions had been recorded. It iswell established that the major sources of nitrogen are agricultural fertilizers andurban waste discharges coming from the upstream watershed. It was concludedthat N 2 O emissions need not be included in future reservoir induced GHGresearch.• For CO 2 , it was noted that emissions measured at the reservoir surface largelyrepresented the product of the natural carbon cycle. In a small number oftemperate and cold/boreal reservoirs, absorption of CO 2 had been recorded at thereservoir surface. Measurements on newly created reservoirs showed an increaseof CO 2 emissions with peak values during the first years after impoundment. Itwas understood that this pulse represented the decomposition of submerged flora,although a substantial portion of the remaining biomass will not decompose andwill be preserved by the reservoir water. Another source of the CO 2 is the releaseof carbon from soils in the drawdown zone. In all reservoirs, the peak of thisactivity occurred generally within the first two or three years after commissioning.It was agreed that the net CO 2 emissions were not significant in relation to thelifespan of most reservoirs.• CH 4 is the most significant GHG in relation to reservoirs. In cold/boreal andtemperate reservoirs, little CH 4 emissions have been recorded. In some cold/borealreservoirs, CH 4 emissions have been detected following the break-up of the winterice cover. In some tropical reservoirs, however, significant CH 4 emissions havebeen recorded. There is a high temporal variability in CH 4 emissions, which needsfurther investigation. In at least one case (Petit Saut, French Guyana), significantCH 4 ‘degassing’ emissions have been recorded downstream of the reservoir.However, based on a limited set of published measurements, it seems that sometropical reservoirs exhibited very low CH 4 emissions.”Run-of-the-river hydropower plants do not cause net emissions of GHG except thecomparatively small amounts of such gases released as a result of manufacturing ofequipment and construction work, including transportation. The total amounts of suchemissions usually fall below 10 g CO 2 -equivalents per kWh 2 .1 http://www.unesco.org/water/ihp/pdf/ghg_participants_statement.pdf2 Svensson, B. (2005). Greenhouse gas emissions from hydroelectric reservoirs: A global perspective. pp. 25-37,In: dos Santos, M.A. & Rosa, L.P. (Eds.) Global warming and hydroelectric reservoirs. Proceedings ofInternational Seminar on Greenhouse Fluxes from Hydro Reservoirs & Workshop on Modeling Greenhouse GasEmissions from Reservoir at Watershed Level. Rio de Janeiro, Brazil, 8-12 August 2005. COPPE/UFRJ,Eletrobrás. 197 pp.7
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Page 5 and 6: AcknowledgementsThis report was pro
Page 8 and 9: a critical evaluation of published
Page 10 and 11: comparable to those from natural la
Page 14 and 15: The harnessing of Sutlej River for
Page 16: ebullition of methane and dissolved

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