Small Decentralized Hydropower Program National ... - Cd3wd.com
Small Decentralized Hydropower Program National ... - Cd3wd.com
Small Decentralized Hydropower Program National ... - Cd3wd.com
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El drenaje de 10s reservorios, sin embargo, podria<br />
causar alteration m8s drastica de1 ambiente acuatico<br />
que 10s metodos de construccidn convencionales. La<br />
mortalidad indirecta de muchos organismos setia un<br />
impact0 temporario. Los organismos serian arrastrados<br />
corriente abajo en ambiente al cual estin<br />
muy pobremente adaptados. Posiblemente podrian<br />
ociirir amontonamientos si 10s organismos (&specialmente<br />
peces) llegaran a aguas estancadas. Probablemente<br />
durante el period0 de construction crecerian<br />
pastas en la base expuesta de1 reservorio, except0<br />
durante el invierno. Los suelos setian aireados, y 10s<br />
minerales, nutrientes y otras substancias pueden ser<br />
mobilizados.<br />
Cuando se vuelva a llenar el reservorio, las <strong>com</strong>uunidades<br />
acwkicas se desarrollaran y pasaran por<br />
una sucesion ecologica hasta que se <strong>com</strong>plete la colonizacion<br />
y 10s ciclos materiales alcancen equilibrio.<br />
Durante este petiodo es posible influenciar la<br />
<strong>com</strong>position de las <strong>com</strong>unidades acuaticas mediante<br />
la implant&on de peces u otras medides. Seria posible<br />
excluir peces rudos y mejorar la calidad de 10s<br />
peces en el reservorio para tener peces m&s<br />
deseables desde el punto de vista de la pesca <strong>com</strong>a<br />
sport y aun de la pesca <strong>com</strong>er&l. No obstante,<br />
podtia requerir varios aiios para que un reservorio se<br />
recupere de1 drenaje y la vuelta a llenar. Estas<br />
tecnicas setian probablemente m5s factibles y aceptables<br />
en reservorins pequenos.<br />
Las otras partes de1 sistema en que ocurren impactos<br />
de la construction son 10s aspectos de la<br />
transmision y distribution. Los impactos de estas<br />
porciones no son exclusives de la hidroelectricidad en<br />
pequena escala. Es decir, que tendetian a ser 10s<br />
mismos :ualquiera fuese la tecnologia de la<br />
generation. Aunque el enfasis de este document0 es<br />
la generation, se hara breve mention a 10s impactos<br />
concernientes a la construction de la transmisidn y<br />
distribution. La construction de estaciones transformadoras<br />
y la construction de lineas de distribution<br />
primaria y secundaria basicamente implican<br />
modification de Ias viviendas terrestres de animales<br />
silvestres. Esta mo~~ificacion consiste principalmente<br />
en la limpieza de cualquier vegetation para construir<br />
la estacion transformadora e igualmente para las<br />
lineas electricas. Esto resultatia en la perdida de las<br />
viviendas de pequenos pajaros de1 campo y de la<br />
selva y de rodent . ,es que ‘rltO1,, * rnn cl ,n IVU In@ rUVYl noc+;zolnc uI..v, cI Qrbustos<br />
y arboles pequenos, o alrededor de ellos.<br />
En sintesis, cuando se construya un dique, 10s m&s<br />
importantes impactos ambientales de la construction<br />
son la sedimentation por el alboroto de1 suelo y el<br />
with physical properties suitable for fish<br />
migration.<br />
Operation<br />
Of the three principal configurations of<br />
impoundment, run-of-river and diversion, by far<br />
the most significant operation impacts are<br />
associated with impoundment.<br />
Aquatic ecology. Water use can be indirectly<br />
affected by stored water, particularly for peaking<br />
power. Pondage can produce pulse flows, i.e.,<br />
periods of below-normal flow while water<br />
accumulates and periods of high flow while<br />
power is produced. Although run-cf-river or diver-<br />
sion operation would be more <strong>com</strong>mon for small/<br />
low-head facilities, some facilities will impound<br />
water and pulse flows can affect downstream<br />
water use and biota.<br />
The type and severity cf these impacts will<br />
depend on preexisting conditions, changes in the<br />
point of water re!ease, and other site-specific fac-<br />
tors. The release of water from turbines typically<br />
produces considerable turbulence in the tailwater<br />
area. This often requires construction or renova-<br />
tion of a stilling basin just below the outlet. Still-<br />
ing basins are lined with concrete or rock to ab-<br />
sorb the turbulent energy of released water. The<br />
turbulence below turbine outlets can scour and<br />
erode the bottom, especially below stilling<br />
basins. This can introduce suspended sediments<br />
and alter the downstream habitat as mentioned<br />
earlier. Effects are more pronounced below larger<br />
dams and with storage operation.<br />
Hydro facilities change the natural patterns of<br />
flow and thus alter many features of downstream<br />
ecosystems. <strong>Small</strong> or low-head hydro plants,<br />
however, produce smaller impacts than those<br />
observed below large storage reservoirs.<br />
Under natural conditions, high flows occur with<br />
snow melt or periods of heavy precipitation, often<br />
in the spring or fall. Storage impoundments<br />
eliminate or greatly reduce flood flows, not only<br />
immediately below the dam, but often for great<br />
distances downstream. Stable flow and<br />
temperature remove cues which trigger migration<br />
or reproduction in some benthic organisms and<br />
fish.1 Power generation introduces short-term<br />
variations in flow in accordance with demand for<br />
electricity. As power generation starts or stops,<br />
streamflows can increase or decrease many-fold.<br />
These variations can be destructive to benthic<br />
organisms and cause a considerable reduction in<br />
diversity.2,3<br />
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