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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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