NonBasicSpecificComments04

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

208

BRrAN D. RICHTER ET AL.

Ecological AppUcations
" VoL 13~ No. 1

Natural State of Freshwater Ecosystem
(natural flow regime)
· maximum richness of native species
· high comple:xity of biophysical habitats

Symptoms of Ecosystem Degradation:

· "declines in commercially or
recreationally important species
· declines in ptQductivity of certain trees
· increases in invasive species
· depletion of water needed to dilute
pollution
· vegetation etlcroachment into
channels
· depletion of nutrient supplies for
floodplain agriculture

· accelerated erosion and sedimentation
· changes in water temperatul'e ~d
recreational appeal
· changes in water chemistry and suitability
for human consumption or industrial use
.. reduced water purification from natural
processing

Altered State of Freshwater Ecosystem

(heavily managed flow regime)
· lower native species richness
· modified abundance and distribution of spepies_
· simplified physical 'structure of ch~nneI and floodplain
· modified water ohemistrY and temperature

FJG. I. When the natural flow reginle of a river is altered ~oo greatly, it wilt trfgger a cascnde ofreac!ions that cause the
river ecosysteul to .simplify over tilne, leading to a degraded state. As a resu1t~ many' hUlnan uses"1 natiyo species, and :Other
.eposystenl servi~es and products can be adveE'~ely affected.

managerllen t is an iterative process in which both ~u-
nlan water dematlds and ecosystem requi rements ate
defined1 refined, and lnodified to meet htunan and eco-
system sustainability now and in the futnre, rather than
a single, one-time solution" This implies an aggressive
and continual se~rch for cOlnpatibility betvleen eco-
systelll and human water needs~ and t"equires a com-
111itn1ent frolU all parties to ongoing participation in an
active dia 10 gue: "
We have developed a fraJ.uework for initiating an
ecologically susta.inable water Inanagement program
(Fig. 2). There are ll1any entry point~ into this process,
but our experience suggests that each step is essential
to achieving ecological, sustainability. Shnilar adaptive
water l'ltanagemerlt frameworks are" now being em-
ployed in South Africa (Building Block MethQdology~
I{ing and Louw 1998) and Australia (Holistic Meth-
odology, Arthington and Zatucki 1998), as well as in
SOUle river basins or states in the United States. In
essence~ what we are describing ill this paper is simply
the translatio-n and application of ecosysten1 lllanage-
ment principles into a water 111anagelnent context. In-
terested readers are refei~red' to Walters and Holling
(1990)~ Lee (1993), Noss and Cooperrider (1994),
Sparks (1995)1 Gunderson et al. (199S)~ and Christen...

"sen et al. (1996) as springboards into the voluminous
literature of ecosystenl management.
In the remainder of this paper we furthe.r discuss the
steps included ill our. framework and provide examples
"of their application in ri.ver systems around the"world.
We also describe a case study fronl the Apalachicola-
Chattahoochee-Flint Rivet' basin in Alabama, Florida,
and Georgi a to illustrate the application of thi s frame...
work to a specific riv>er basin.

'STEP 1: ESTIMATING ECOS'VSTEM
FLOW REQUIREMENTS

Water n1anagement is driven by quantified objec-
tives, e.g., specified levels of flood protection. gener-
ation of hydropower, or reliability of water" supplies
during drought. SiIniJarly, water-reLate:d ecological ob-
jectives need to"be quantitatively defined' 8_0 that they
can be integrated with other water managel11ent obJec..
tives (Rogers and Bestbier 1997).
Many different aspects of hydrologic variability can
influence freshwater biota and ecosysteln processes,
but in constructi.ng ecosystem fipw prescriptions riv.er
scientists generally focus on these key- cOffi'ponents of
flow regimes: wet- and dry-season base .flows. normal
high, flows, extrellle drought and flood conditions that