Recharge d'une retenue hydroélectrique stratifiée tropicale après orage (retenue de Petit Saut, Guyane Française) / Storm recharge of a stratified tropical dam reservoir. The Petit Saut dam reservoir, French Guyana, South America

摘要

Abstract : Storm recharge of a stratified tropical dam reservoir. The Petit Saut dam reservoir, located in French Guyana, South was investigated in wet and dry season. Temperature, pH and oxygen content vertical indicate a clear stratification in dry both at the middle of the reservoir as well as lateral branches. In wet season the stratification is not as sharp, and diffusion calculations indicate the presence of turbulence in the deepest part of the reservoir. vertical oxygen content profile of the was studied in a lateral branch of the lake, before and after a storm event. It indicates lake recharge does not occur by the nium. Runoff leads to the discharge in lake, only a few hours after the storm event, cooler and thus heavier waters than the nic waters. These waters intercalate the epilimnic and the deep hypolimnic waters. This water layer creates an additional barriers for the gas produced in the nium (CH4, Hg°) in their migration -via diffusion- to the atmosphere. This laminar does not create the turbulence which would required to oxygenate deep anoxic waters. As a consequence the oxygénation such hydroelectric reservoirs built in tropical countries by flooding primary rainforest is very slow process.