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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Es de suma importancia que la investigaci6n<br />
incluya un reconocimiento de la literatura existente<br />
ya que muchos anklisis regionales pueden haber sido<br />
<strong>com</strong>pletados. Dos reportes monumentiles que pro-<br />
veer&n exce!ente informaci6n especifica y<br />
generalizada y que pueden prestar valiow asistencia<br />
ban sido producidos por ia Divisi6n de Ciencias<br />
Acu&tkas de la Unesco (1977, 1978). La informacicin<br />
y mapas sobre lits balances acu6ticos mundiales so:1<br />
especialmente titiles en Breas donde existe muy poca<br />
informaci6n.<br />
Un modelo desarrollado para utilizarlo donde ~610<br />
erriste informacibn sobre precipitaci6n y tempera-<br />
turas es presentado en la ouia de la OMM, (1970). El<br />
metodo est.5 basado en una relaci6n entre PIE y<br />
R/E, donde P es el promedio anual de la precipita-<br />
ci6n, R es el promedio anual de la afluencia de1 rio, y<br />
E es un factor temperatura. Se puede calcular el<br />
valor de R (afluencia) usando las tablas T y E, y P/E<br />
jr R/E. Se pueden elaborar refinamientos para ciertas<br />
regiones en las cuales las lluvias caen dentro de<br />
ciertas estaciones.<br />
Modelos Deterministas y Estodsticos. E!<br />
reconocimiento de que el ciclo hidrol6gico es un<br />
sistema extremadamente <strong>com</strong>plejo ha traido <strong>com</strong>a<br />
consequencia el que uno mantenga un metodo de<br />
“sistemas” al iniciar un estudio sobre oportunidades<br />
de desarrollo de 10s recursos acu5ticos. La construc-<br />
ci6n de modelos se ha convertido en un element0<br />
b&co en lo que se ha venido a conocer ccmo un<br />
“sistema de anglisis” o una “investigaci6n opera-<br />
cional.” El fin de1 proceso es, naturalmente, el de<br />
asistir para identificar aquellas medidas de control<br />
que contribuitian a asegurar la culminaci6n de 10s<br />
objetivos planeados.<br />
Generalmente dos clases de modelos matem$ticos<br />
pueden ser identificados <strong>com</strong>a importantes desde una<br />
perspectiva de planeamiento (FAO, sin fecha):<br />
“(i) - modelos de simuluci6n descriptiva que rela-<br />
cionan dentro de un sistema 10s insumos a su pro-<br />
ducci6n atravez de un procedimiento <strong>com</strong>putational<br />
direct0 y por el cual se rotan varias veces para<br />
examinar las implicaciones de adoptar diferentes<br />
alternativas de disefio;<br />
(ii) - modelos analiticos optimixadores, prin-<br />
cipalmente de la variedad matemhtica pro-<br />
gramadora que intenta determinar la forma 6ptima<br />
de lograr un objective.”<br />
Ambas clases de modelaci6n pueden ser utilizados<br />
para el desarrollo de proyectos de hidroenerda. Los<br />
modelos optimizadores pueden ser particularmente<br />
valiosos donde la hidroenergia vaya a ser agregada a<br />
38<br />
which either (1) thermal systems are reasonabie<br />
alternatives to be considered, or (2) the existing<br />
system contains thermal energy production and<br />
the hydropower must be properly valued.<br />
in less <strong>com</strong>plex situations, one may be more<br />
interested in simulating the hydrologic system<br />
than in optimising the operation, at least during<br />
the early stages of investigation. In mini-hydro<br />
investigations, one is probably uninterested, ex-<br />
cept in a theoretical way, in any simulation what-<br />
soever.<br />
The classification of simulation models is not<br />
ail that well-defined. There are those that claim<br />
to model the physical processes, while others are<br />
presented as being only approximate (based on<br />
empiricisms).<br />
As Diskin (1980) indicates,...“The most impor-<br />
tant problem to the potential user [of models] is<br />
probably the choice between the <strong>com</strong>prehensive<br />
model versus the specific model. The <strong>com</strong>prehen-<br />
sive model claims that it reproduces all pro-<br />
cesses that take place in the watershed. it is<br />
thus presented as a tool that can meet the needs<br />
of ail potential users. The specific model, as its<br />
name impiias, is intended to supply only one type<br />
of design data. An example of such a model may<br />
be one producing monthly runoff volumes. Other<br />
examples include a model producing snow melt<br />
hydrographs or a model for converting extreme<br />
storm rainfalls into design runoff hydrographs. A<br />
specific model also usually produces other data<br />
as a by-product, but the accuracy and value of<br />
these additional data are inferior to those data<br />
for which the model is cor?structed.” He con-<br />
cludes..., “Practice gained in the analysis and use<br />
of various modeis appears to be the only tool<br />
available to the applied hydrologist for assessing<br />
the usefulness of a hydrologic model in the pro-<br />
cess of planning and management of a water<br />
resources project in a given watershed”<br />
(emphasis added). As a matter of policy, it is<br />
probably beneficial to introduce modeling capa-<br />
bilities early in the planning process, since the<br />
development of capabilities is not without pro-<br />
blems inherent in the learning process. Further-<br />
more, modeling may also assist in guiding the<br />
decision to implement data collection networks.<br />
in general two approaches are used in the<br />
development of hydrological models: stochastic<br />
or deterministic (and, of course, <strong>com</strong>binations of<br />
the two).<br />
in the stochastic approach, the variables