Small Decentralized Hydropower Program National ... - Cd3wd.com

Q50 puede ofrecer buenos estimativos para la energia
primaria, siendo stzundario cualquier otro valor por
encima de este. Las Figuras 2 a 4 ilustran algunas de
las diferentes t&micas de la duration fluvial por
medio de ejemplos. La experiencia ha demostrado
que 10s valores Q20 o Q30 son excelentes pimtos de
partida para determinar el tamaiio de1 equipo.
En ciertas partes de1 m-undo la experiencia ha
demos&ado, o 10s estudios hidrologicos pueden
sugerir, que 10s promedios fluviales anuales pueden
ser calculados en base a ciertas variables claves. En
Nueva Inglaterra (E&ados Unidos), por ejemplo, se
ha descubierto que la, precipitacidn varia entre 20 N a
30” por aiio. Una regla empirica bastante util (Mayo,
sin fecha) es la de suponer que 2 pies ctibieos ,por
milla cuadrada de area de drenaje corresponde al 20
6 30 porciento de excedente fluvial.
Frecuentemente en 10s paises en desarrollo la in-
formacidn sobre el sito para basar analisi hidro
16gicos es bastante limitada. Alin en 10s E&ados
Unidos, un pais que en tirminos generales puede ser
considerado rice en information, es necesario casi
siempre ajustar la information remota.
El estudio recientemente completado en el
Instituto de Investigation de Recursos Acuaticos de
Idahc (Gladwell, et. al., 1979) fijo coma uno de sus
objetivos formular un analisis complete de1 potential
hidroelectrico de1 sistema fluvial de1 Rio Columbia en
10s Estado Unidos. Decidimos uti!izar el
procedimien to de duration fluvial cotidiana conjun-
tamente con hidrograficas de1 promedio anual. Como
era evidente que tal tarea excediria en gran parte
nuestra abilidad para depender en calibradores
“cercanos”, necesitamos emplear un metodo
diferente. Se desarrollo un metodo regionalirado in-
cluyendo la disponibilidad de un estimativo de1 pro-
medio de 10s valores de la precipitacidn anual. Los
procedimientos utilizados permitieron el desarrollo de
curvas sintiticas de la durcion fluvial a cualquier
punto de cualquier rio de la region, dentro de 10s
limites de1 proceso. Esto, en ccombinacion con la in-
forma&n fisica de1 sitio permitio que se calculara la
energia potential bajo una serie de supuestos niveles
de capacidad instalada.
Si se han de comparar registros entre si, o se 10s
utilizara en analisis regionales, naturalmente ellos
tendran que representar periodos concurrentes. Es
importante que la diferencia en 10s registros refleje
aquelias caracteristicas de clima y o drenaje de la
cuenca y no simplemente aquellas pertinentes a 10s
diferentes periodos de tiempo. Aunque no se contem-
ple realizar estudios regionales es importante ex-
49
the flow below the reservoir will have flow-
duration characteristics as indicated in the
regulated flow-duration curve shown in Figure 6.
Such flow regulation would obviously make the
turbines’ use more effective by storing the higher
flows when they appear and making them
available during times when the flows would
have normally been lower. In Figure 6! the volume
of flows represented by abed must equal that of
efgcd. The shaded area represents flow from
storage. As a practical matter, it means that if,
for example, we had installed a turbine with flow
capacity equai to level f-g, then with the
regulated flows it would run for 100% of the
time. With unregulated flows, it would run under
partial loads for periods of time.
Site Hydraulic and Physical Characteristics
it should be understood that the hydrologic,
hydraulic and physical characteristics referred to
in this paper are limited in general to those
directly influencing the hydroelectric generation.
Considerable engineering work will also be
necessary for dam design and general safety
considerations - including safe and economic
flood-flow passage. Where an existing dam is
being considered, it is particularly important that
a satisfactory safety inspection be made by a
competent engineer.
The hydraulic head and variations thereof avail-
able for generation of hydro power is, of course,
related closely to the development scheme
devised. Where high heads are being developed,
the variation may be minimally important.
However, in lower head systems, it is important
to study the site and proposed development
scheme carefully to determine the relationship of
head to discharge both in the reservoir (where
used) and in the tailwater area. In this case, the
maximum head will generally be available at
lowest flows, whereas it is quite possible for the
available head to be so small at extremely high
flows as to make negligible the amount of power
produced.
Although most small hydro developments will
tend towards run-of-river, it is quite possible that
a reservoir produced may be of sufficient volume
to offer some regulation capability. It is, in any
case, necessary to study the reservoir character-
istics to determine the area to be inundated.
Characteristics to be determined will include
stage-capacity and area-capacity relationships,
areal extent, and backwater effects. The physical