NonBasicSpecificComments04

• Title: Comments 4
• Date: 10/23/2003
• SWSI - Doc Type: Comments

Februal)' 2003

ECOLOGICALLY SUSTAINABLE WATER MANAGEtv1ENT

r~~~~~~--~~-~~~~--~--~~~~~~~~~~~~~-~~-~~~~~--~-~~~~
I' 1 I
,~ Step 1 ~ Step 2 l
. J ~
~ I
I I
l I
r:: I r
01 t
E I t
ell
'tii t :
c i
e I
II) .1
~ :
e I
~ I
I
1
~
~
I
I
i
1

-__J

1--- -.--- ---,

I 1
, I
rJ) l Foster CoUabbrative I
C I Dlatogue to Search l
~ ! for Solutlqns :
. 0 l I
i i Step 5, ~ i, . . f
.c f Conduct Wat~r . . -1-,
~I ' 1
- m I ' Managenient l
fJ'J l experiments to I
t Sesol\l8. u.nc+rtalnty r
I ~
~ __ _- _- _- _- __ _ - _- _- _- _"- -- -- -- _- _--- __ -- -- -- ~___ t-+~ -- -- -- -- -- -- -- -- -- ---- -- ---- -- -- -- -- -----~,
I . Step B :t, ..- . l
I ~ .
en Design and ,ImPlement. . I
~ ~ I . an Adaptive . l' '
~ G) ~ Manageme~t Plan' I
ct 0)1 Yo I
"1:1' co l · monnor ng "
< a ~ · fundln:g ,
~ · gOV'8rnarce ,
. I · adaptability. . . 1
, ~
I ; - I

---~~~~~~~~-~~~~~~~--~~-~~-~~--~~~~-~~~~~~--~--~~~-

Fso. 2. A fran1cwork for ecologically s~staina~lo ,w~ter management,

do not occur every year; rates of tlood rise and fan;
and the interannual variability in each oftllese elements
(ArthillgtOl'l and Zalucld' 19981 King and Louw 1998,
Trush et at 2000), The particular .flow components 0 r
statistics used to define flow requirements in different
parts of the world necessarily vary to some degree,
depending upon regional differences i-q. annual hydro-
logic patterns. Ecosystem flow requirements can be
, specified as numerical ranges within which the flow
component is to be maintained (o.gq Fig. 3; Richter et
aI. 19970), or they can be ej(pressed as threshold li1nits
for specific flow characteristics (Table 1" Fig. 4) that
should not be crossed (Rogers and Biggs 1999, Richter
alld Richter 2000). '
Generally, the greater the numbeL' of flow character..
istics used to describe ecosystem requirementst the bet-

209

- ,

I

ter Ithe chanoes of attaining the desit-ed flow regime~ .
On lthe other hand, the flow needs should be described
usi~g .only as many characteristics as necessary. It is
usuJally possible to identify a limited number of chaL~'"
act~ristics necessary to describe.flow conditions of con..
cerp. For exanlplel even thOl.lgh natural ,floods are es..
se1'l:tial in sustaining river ecosystems, their natural V~l.'"
iab!lity may not be constrained in a particular water-
shdd in the absence of dams.. Therefore)' there may be
. no lnetd to prescribe flood flow characteristics unless
ne~ dams are proposed in the future. This Inay help
Si~plify the assessment of th,e ecological suitability of
va~ious water management alternatives.. Prhnary ntten...
tiOf should be given to flow characteristics that have
be4n or may be altered by human influences (Rogers
an~ Bestbier 1997, Rogers and Biggs 1999)~