Environmental flows in Europe

Mike Acreman

Green and pleasant land?

Thames basin10,000 km2

650 mm rainfall 15 million people

significant water stress

recycled 7 times

The River Thames 1858•The Great Stink•Smell of Thames - untreated human waste and effluent

•Parliament suspended•Prompted sewerage

The River Thames 2008

• Fishing, boating, swimming ....

• Spiritual re-connection• Eco services restored

e.g. water purification

• 2015 Winner of International Theiss River Prize

150 years of work

Clear long term visionA journey with people Key steps 1865 2015sewerage installedindustrial pollution controlenvironmental flows nutrients (P stripping) nano-particles, oestrogenwater trading

You can’t please all of the people all of the time

but you can please some people some of the time

• 2000 years of management

• Important heritage• Protected for

managed habitats• Natural conditions not

desirable

Which reference conditions?

natural10,000 BC

golden age1821

when I was young

European Water Framework Directive

(nearly) totally undisturbed

slight alterations

moderate alterations

major alterations

severe alterations

High

Good

Moderate

Poor

Bad

OK

Reference Conditions

can’t do Good Ecological Potential

Ecological Status

measuresneeded

Integrated status

• Chemical status - pollutants, oxygen, acidity ...

• Biological status - algae, macrophytes inverts, fish

• Hydro-morphology – flow, channel naturalness

Thames River Basin Plan

Contents• Current state• Actions to improve• Future state (targets)• Implementation plan• Adaptive management

developed through consultations with organisations and individuals

River management classes

High class - naturalGood - semi-natural Moderate - working riverBad - polluted river

2012 Blueprint to Safeguard Europe's Water Resources

Pressure on river ecosystems• No 1 pressure = dams, land

drainage; flood embankments

• No 2 pressure = over-abstraction of water → identification of “ecological flow”

Natural river flows

time

dis

ch

arg

e

channel maintenance flood

floodplain connectivity

maintenance flows for spawning and dispersal

freshet trigger flows for migration

low flows for juveniles

J F M A M J J A S O N D

All aspects of the flow regime are important for some element of the river ecosystem

not right

Specifying environmental flows

Direct abstraction

Reduced baseline – maintain variability

Restrictive management

Impoundment

Magnitude and variability may be reduced; magnitude may be increased

Active management

Abstraction management

• How much can we alter the flow regime ...

• ... but maintain desired conditions?

• Current UK standards -developed by expert panels – i.e. synthesis of knowledge and experience

Type or sub type

Season flow > Qn60 Flow > Qn70

flow > Qn95 flow < Qn95

Apr – Oct

30 25 20 15 A1

Nov – Mar

35 30 25 20

Apr – Oct

25 20 15 10

A2 (ds), B1, B2, C1, D1

Nov – Mar

30 25 20 15

Apr – Oct

20 15 10 7.5

A2 (hw), C2, D2

Nov – Mar

25 20 15 10

Jun – Sep 25

20

15 10 Salmonid spawning & nursery areas (not Chalk rivers)

Oct – May 20 15 flow > Q80

10 flow < Q80

7.5

Headwaters

Maximum abstractions % to meet GES

Lowland meandering

Middle reaches

High flow DroughtMedium flow

Low flow

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14 16

flow

eco

log

ical

sco

re

UK Evidence of ecological response to flow

LIF

E s

core

Flow index

1991

1997

2001

2009

No threshold

flow flow flow

flowflowflow

Eco

syst

em s

core

Eco

syst

em s

core

Eco

syst

em s

core

Eco

syst

em s

core

Eco

syst

em s

core

Eco

syst

em s

core

sensitive riverslow abstraction

robust rivershigh abstraction

River sensitivity

Impoundment releases

Heavily Modified Water Body

Target = Good Ecological Potential

Best practice

Stakeholder objectives

Dams have major control over flow regime

Design flow releases to meet desired ecosystem services

E-flow releases for GEP

time

dis

ch

arg

e

channel maintenance flood

floodplain connectivity

maintenance flows for spawning and dispersal

freshet trigger flows for migration

low flows for juveniles

Quantity – magnitude, timing, duration, frequencyQuality – temperature, sediment

E-flow release regime

time

dis

ch

arg

e

environmental flow

natural flow

Risk of future ecological impact from hydrological alteration

Adaptive management

• E-flow assessments uncertain

• Responses un-predicable• Circumstances change• Need to act, monitor,

evaluate and adjust• Not admission of error

Paradigm change (after WWAP)

EIA

EOA

Solutions in Thameswetlands, floodplains restoration to store water and purifies it naturally- multiple benefitse.g. human health

Water trading; water saved can be sold to another user

New reservoir – last resort

Floodplain wetlands control floods

1998 flood flow Oxford

with no floodplain

Conclusions• Decide what you want to achieve• Set long term goal and small steps• Define baseline and objectives• No simple answer, choose appropriate method • Develop indicators that response to flow• Define impacts of future climates/water needs• Looks for opportunities of ecosystems• Take adaptive management approach

THANK YOU