Geoscience Reference
In-Depth Information
Table 4.1
(
Continued
)
Task 6
Ecological and social importance and sensitivity
Define the priority of the area of interest from an ecological perspective (e.g. number of sensitive and rare
species, the resilience of the system to human disturbance, importance as a migration route).
Task 7
Define reference conditions
Define the reference (usually natural, unmodified) physical, chemical and ecological conditions as a baseline
against which to judge how much the river has been modified.
Task 8
Define present ecological status
Define present hydrological, physical, chemical and ecological status based on available data and expert
judgement.
Task 9
Define environmental objectives
Define the most appropriate environmental objectives given the nature of the system, priority uses, and
ecological goods and services.
STAGE C: EFA WORKSHOP
Decide upon flow recommendations (including wet and dry season baseflows, and floods) using inputs from all of the
specialists. Decisions should be made considering all of the identified environmental objectives.
STAGE D: NEGOTIATION
Task 1
Hydrological yield analysis
Calculate the likelihood of being able to maintain the environmental flows and supply the user needs, in wet
and dry years.
Task 2
Scenario analysis
Analysis of different water allocation scenarios (including environmental flows) at different levels of assurance,
to provide the basis for negotiations and decisions where there is insufficient water to meet all requirements.
Task 3
Decision
To allocate water for the recommended environmental flows, or to accept one of the above scenarios.
STAGE E: IMPLEMENTATION AND COMPLIANCE MONITORING
This culminating step in the process lasts indefinitely. Methods of implementation depend on the availability of storage
structures, inter-basin transfers, or potential for demand management on any specific river. Initiate long-term monitoring
and refinement of flow requirements.
choice of method to use will be governed by
the available resources (time and money), and
the levels of expertise and information available
in the required disciplines. Generally, quicker
and cheaper methods provide less confident
recommendations lacking specific environmental
motivations, but all recommendations can only
be as confident as the available data allow, no
matter which method is employed. For example,
a lack of long-term measured flows will inevitably
compromise confidence in the recommended EFA,
regardless of how detailed the ecological and other
datasets are.
During the 1980s, primarily in Australia, the
United States and South Africa, pioneering projects
were undertaken to investigate the effects of
modified flow regimes on the ecology of rivers
(e.g. in the rivers of the Kruger National Park,
as described in O'Keeffe and Rogers, 2003).
In the 1990s environmental flows began to be
implemented, Poff
et al
. (1997) synthesized the
general relationship between flows and river
ecology, and the ground-breaking South African
Water Act was passed in 1998 - the first time
that environmental flows (the ecological reserve)
were included explicitly in water legislation. Since
the beginning of the new millennium, countries
from all around the world have committed to the
implementation of environmental flows. In the
past five years, the WWF, in partnership with the
