Ankara | 21 November 2013 Intro to sustainable hydropower and environmental flows Key Issues, intro to methods Dr. Jian-hua Meng, WWF International Environmental Flows Workshop
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Ankara | 21 November 2013
Intro to
sustainable hydropower
and environmental flows
Key Issues, intro to methods
Dr. Jian-hua Meng, WWF International
Environmental Flows Workshop
Dr. Jian-hua Meng, WWF International
Environmental Flows Workshop
welcome back !
Environmental Flows
Flow is the 'master variable'
Richter, TNC
Intact freshwater ecosystems are fundamental
Ecosystem goods and services
foods production
drinking water supply
agricultural water supply
groundwater recharge
water quality restoration/regulation
economic goods
cultural / heritage / spiritual services
floodplain storage
river delta / estuary protection
coastal and marine systems
...
River flows. Environmental flows. Free flowing rivers
Provisioning Services: drinking and
irrigation water, a source for food and
energy, and an economic basis
Regulating Services: water purification,
groundwater stock balancing and feeding,
salinity prevention, flood mitigation,
sediment transport and retention
Cultural Services: recreation, aesthetic
and spiritual values
Supporting Function: nutrient cycling,
primary production, habitat provision,
biodiversity maintenance
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Sediment deficit – Mississppi example
1930
source: Dan Swenson, The rise and
disappearance of Southeast Louisiana,
http://www.nola.com/speced/lastchance/
multimedia/flash.ssf?flashlandloss1.swf
today
1930
Engineering Era Flow releases for:
• Hydropower generation
• Downstream allocations
(e.g. agriculture, cities)
• Navigation
• Dilution of pollution
Common to have zero flow
McClain, UNESCO-IHE
Hoover Dam
Glen Canyon
Dam
McClain, UNESCO-IHE
First approaches: Tennant Method
• Based on field studies from 11 streams in 3 States conducted between
1964 and 1974
• Involved physical, chemical, and biological analyses
• Seasonally variable base flows and flushing flows
• Recognized as a reconnaissance-level method
Tennant, 1976
McClain, UNESCO-IHE
Ecological Era
Tennant, 1976
• 10% of the average annual flow was found to be the minimum
instantaneous flow needed to sustain short-term survival.
• A flow of 30% of the average annual flow was required to maintain
good habitat for aquatic life; at this flow, widths, depths, and
velocities were generally satisfactory, streambanks provided some
cover, and larger fishes could pass most riffles.
• Optimum habitat was provided by flows of 60-100% of the average
annual flow and flushing flows were 200% of the average annual
flow.
Tennant, 1976
McClain, UNESCO-IHE
Environmental Flows The Brisbane Definition
“Environmental flows” describe the quantity,
timing, and quality of water flows required to
sustain freshwater and estuarine ecosystems
and the human livelihoods and well-being that
depend on these ecosystems.
Richter, TNC
Environmental Flows How this translates to dams operations
“How much, and at what times, must water be
released from the dam to sustain ecosystem
health and services?”
Richter, TNC
Environmental Flows
Richter, TNC
All Methods Begin with Objective Setting
• What is the desired ecological state of the river?
• Which environmental services are to be maintained
and for whom?
– Fisheries (food & recreation)
– Water purification / sediment retention
– Flood protection
– Riparian forests
– Recreation (e.g. rafting)
– Esthetics & cultural heritage
• Which national laws or policies are affected?
Classification – example South Africa
Environmental Flows
Richter, TNC
ONE YEAR
Natural flows
Environmental flows
F
L
O
W
A) RIVER FLOWING THROUGH A CONSERVATION AREA
ONE YEAR
Natural flows
Environmental flows
F
L
O
W
B) RIVER FLOWING THROUGH AN URBAN AREA
Classification – EU
Basic Approaches to setting Eflow Standards
• Minimum flow thresholds – Annual or seasonal minimum flow levels
to not be undercut
• Systematic construction of a modified flow regime
– Specification of flow elements representing well defined
features of the flow regime intended to achieve particular
ecological, geomorphological, water quality, social or other
objectives in the modified system
• Variation percentage of natural flow
– Bands of allowable alterations
from the natural flow regime (sustainability boundaries)
Minimum flow thresholds
Single or seasonal minimum flow level not to be exceeded
– 7Q10: 7-day minimum flow with a recurrence period of 10 years
(originally intended for pollution control)
– Q95: daily or monthly flow that is exceeded 95% of the time
(other exceedence levels may also be selected)
– x % Mean Annual Flow: commonly set at 30%, although
common to vary seasonally (e.g. 50% in summer, 30% in winter,
40% in fall and spring)
Little attention to natural variability of rivers or to ecological
or other social needs.
No ecological basis for low flow threshold.
Percent of Natural Flow Regime
Day of Year
Riv
er
Flo
w o
r W
ate
r L
eve
l
High Flows
Sustainability Boundaries
Normal or Low Flows
Baseline Conditions undepleted and unregulated
Richter et al. (2011)
Day of the year
Riv
er
Flo
w
High Level of
Ecological Protection
+/- 0-10% from natural
Moderate Level of
Ecological Protection
+/- 11-30% from natural Natural Flows
(undepleted and unregulated)
Increasing Ecological Risk
Increasing Ecological Risk
Presumptive Standards – Sustainability Boundaries
Richter et al. (2011)
Systematic construction
of a modified flow regime
LOW FLOW
(first building block)
SPAWNING/
MIGRATION
FRESHES
(third building block)
HABITAT MAINTENANCE FLOOD
(second building block)
CHANNEL MAINTENANCE/
FLUSHING FLOOD
(second building block)
Dis
ch
arg
e
Months
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
LOW FLOW
(first building block)
SPAWNING/
MIGRATION
FRESHES
(third building block)
HABITAT MAINTENANCE FLOOD
(second building block)
CHANNEL MAINTENANCE/
FLUSHING FLOOD
(second building block)
Dis
ch
arg
e
Months
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Environmental Flows
Operation Scheme for Savannah River
Richter, TNC
Scoping
Geomorphological
Survey
Selection of
Study Sites
Definition of Present
and Desired
Ecological Condition
Biological
Surveys Social Surveys
Water Quality
Assessment
Hydraulic
Analysis
Hydrological
Analysis
Workshop to Establish
Flow Recommendations
Communicate
Recommendations to
Policy Makers
Preparatory
Phase
Assessment
Phase
Synthesis &
Consensus-Building
Phase
Detailed studies &
Selection of indicators
Facilitated process
using data, models,
& expert knowledge
to reach consensus
Objective focused
UNESCO-IHE / McClain (2013)
Implementing
Environmental Flows
1. Fully engage stakeholders in every aspect of eflow assessment and decision-making.
2. Identify and grasp opportunities for eflow integration.
3. Define eflow needs using a holistic approach, utilizing the best available knowledge and tools
4. Assess eflow needs before designing a dam’s structural features.
5. For existing dams, seek to integrate eflow needs and implement opportunistically.
6. Be clear about desired outcomes and the flows necessary to achieve them, and monitor outcomes during implementation.
www.hydrosustainability.org
The Protocol
Downstream Flows – basic good practice
www.hydrosustainability.org
28
Downstream Flows – best practice
www.hydrosustainability.org
29
Key Issues, intro to methods
Dr. Jian-hua Meng, WWF International
Environmental Flows Workshop
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