Introducción al Cálculo de Caudales Ecológicos - Endesa..

INTRODUCCIÓN AL CÁLCULO DE CAUDALES ECOLÓGICOS / Un análisis de las tendencias actuales
Alternative
Policy Element: Maximum Cumulative Diversion
Regionally Protective? Basis
MCD1 (Rate): MCD Rate = 15% of 20% Yes Generally allows the lowest
Winter (12/15-3/31) Exceedance Flow
instantaneous rate of diversion. Likely
results in negligible channel change
over the long term.
MCD2 (Rate): MCD Rate = 5% of 1.5 yr Yes Allows a higher instantaneous rate of
flood peak flow (annualized series)
cumulative diversion than MCD1 and
MCD4. This alternative will likely result
in long term adjustment and reduction
in channel size, but the potential
change is thought to be minor in terms
of bankfull width, depth, and surface
grain size distribution. Basing a MCD
rate on the 1.5 year flood peak flow
rate more directly accounts for the
relation between channel size and
instream flow need.
MCD3 (Volume): MCD Volume = Partially May not be protective of coho and
No restriction on diversion rate,
Chinook upstream passage and
stop diversion after the ratio of
spawning habitat flow needs during
total cumulative diverted volume to
the first month of the diversion
unimpaired runoff volume = 10%
season (for DS1 or DS3) in dry and
average years. May not be protective
of channel maintenance flow needs.
Protectiveness is related more
defensibly to flow rate rather than
volume.
MCD4 (Rate): MCD Rate = Diversion Yes, but impractical to apply Provides a comparable level of
rate that corresponds to a half-day
instantaneous diversion rate to MCD1
reduction in the duration of time that
(15% of 20% winter exceedance flow).
flow is above the MBF during a 1.5
Likely results in negligible channel
year flood event
change over the long term. Impractical
because its implementation
requires detailed hourly hydrograph
information for each stream.
Biological Recommendation: Apply Alternative MCD2. There is uncertainty in defining the maximum
amount of change in channel maintenance flows that could occur that would
still be protective of anadromous salmonid habitat. Regardless of which MCD
alternative is chosen for the Policy, effectiveness monitoring data collected
over a period of 10 to 20 years would be needed to assess whether the Policy
could be reopened in the future to include a less restrictive MCD that would
still be protective of channel maintenance flows while offering the opportunity
for higher diversion rates.
Tabla B5
Criterio del Estado de California para reglamentar la cantidad de agua que puede ser extraída de un cauce.
Fuente: State Water Resources Control Board, California.
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