Science that should help find solutions:

Hydrology and water resources

Matthew McCartney

SRP-Basins

Entry points

• Understand and consider resource variability in basin management• Invest in water infrastructure• Allocate and manage basin water and land to raise productivity,

improve equity and safeguard ecosystem services• Introduce and consistently follow the principles of benefit sharing• Pay attention to the political economy of policy selection

1. Understand and consider resource variability in basin management

Needs:

DataBasic understanding of hydrological processes

020406080

100120140

1 10 100

Peak

floo

d flo

w (m

3 s-1

)

Return period (yrs)

Flood Frequency

Extrapolated

0.01

0.1

1

10

0.1

0.5

0.9 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96

99.1

99.5

99.9

Q/Q

me

an

% time flow exceeded

Flow Duration curves

Characterize variability

Seasonal variationFlow duration curves Flood frequency analyses Low flow analysesAssurance levels

volumes of water that can be guaranteed with different degrees of certainty

Rainfall, River flows and Groundwater

Trend analyses

India – significant rainfall trends (1951-2007)

-100

-80

-60

-40

-20

0

20

40

60

80

100

Accr

a Ai

rpor

t

Ada

Foah

Akus

e

Axim H

o

Kete

Kra

chi

Kum

asi

Nav

rong

o

Saltp

ond

Tam

ale

Wa

Wen

chi

Yend

i

Ejur

a

Kpev

e

Zuar

ungu

Regi

onia

l tre

nd

Sign

ifica

nce

leve

l of p

ositi

ve o

r ne

gativ

e tr

end

(%)

Ghana - For variables exhibiting regionally significant trends the number of individual stations with significant trends is less than 50% of total stations

Not just total rainfall/flow but other significant variables (e.g. no. of rainy days; onset of rainy season)

Regional significance not just individual stations

0.00

200.00

400.00

600.00

800.00

1000.00

1200.0019

20

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

2015

2020

2025

Ne

t w

ate

r d

em

an

d (

Mm

3 )

Irrigation Rural Urban

Mining Forestry Historic (5 year running mean)

Low Demand Scenario Medium Demand Scenario High Demand Scenario

Bas

elin

e

.

Future

Historic

• Changes in demand vary between years (particularly irrigation) and experience trends

• Future development is inherently uncertain so must think about scenarios

Changes in demand

Olifants: Simulated changes in demand

0

200

400

600

800

2 5 10 25 50 100 200

Co

st (

US

$)

Return Period (yrs)

Irrigation

Baseline Low DemandMedium Demand HighDemand

Evaluate the financial “cost” of failing to deliver water in different sectors

Olifants – cost of failing to deliver water for different return periods and different development scenarios

Link to economics

2. Invest in water infrastructure

Must be able to evaluate range of storage options combined within a basin

Storage need

Need and effectiveness

RRV criteria

Reliability: the probability of the storage to meet demand

Resilience: the speed of recovery of storage from failure

Vulnerability a measure of the cumulative maximum extent of failure

Storage Effectiveness

Role of natural infrastructure

Monthly flow upstream and downstream of the Luswishi floodplain

0

20

40

60

80

100

1-O

ct-8

0

1-No

v-80

1-De

c-80

1-Ja

n-81

1-Fe

b-81

1-M

ar-8

1

1-Ap

r-81

1-M

ay-8

1

1-Ju

n-81

1-Ju

l-81

1-Au

g-81

1-Se

p-81

Flow

(m3 s

-1)

Daily flow with and without floodplain

Without floodplain (simulated) With floodplain (observed)

Some ecosystems act like natural reservoirs and regulate flows: • decrease wet season flows • increase dry season flows

Method whereby natural flow regulating impacts can be quantified and incorporated in decision-making

Means that basins with both built and natural infrastructure can be considered in decision-making

3. Allocate and manage basin water and land to raise productivity, improve equity and

safeguard ecosystem services

The ChallengeTo devise strategies that support human development (improve livelihoods) and simultaneously safeguard ecosystem services

How to achieve wise use of basins in any specific social, economic and ecological setting?

Ecosystem Services

Getting it wrong

• Inappropriate agricultural practices…. not only destroy other ecosystem services (regulating, supporting and cultural) but also undermine agriculture

Degraded landscapes in Ethiopia(photos by Adrian Wood)

Provisioning services

Regulatory services

Cultural services

Supporting services

Natural basin

CropsHydropower

IndustrialRegulation of water balance

Erosion control

Climate regulationSoil

formation

Nutrient cycling

Recreation

CropsHydropower

IndustrialRegulation of water balance

Erosion control

Climate regulationSoil

formation

Nutrient cycling

Recreation

Intensively utilized basin

CropsHydropower

Industrial Regulation of water balance

Erosion control

Climate regulationSoil

formation

Nutrient cycling

Recreation

Multifunctional “green” basin

Striking a balance

Linking ecosystem services and water productivity

Quantifiable Non-quantifiableBenefits

Wat

er u

se

Dep

letin

g use

sN

on-d

eple

ting u

ses

Developing a framework to effectively compare parallel benefits is extremely difficult.

One possible approach is expanding the water productivity concept

Environmental flows

0

100

200

300

400

Jan

Feb

Mar

Apr

May Ju

n

Jul

Aug

Sep Oct

Nov

Dec

Flo

w (

m3 s-1

)

Flow (1959-1995) Environmental Flow Requirement Flow (2001-2006)

Many methods for estimating EFs – ranging from simple low confidence desktop approaches to complex resource intensive multi-disciplinary studies

Need methods that are applicable to developing countries but for which we can be confident about the results and link to livelihoods

Tis Issat Falls, Blue Nile

4. Introduce and consistently follow the principles of benefit sharing

Schematics of WEAP modelling for Lake Tana sub-basin

Regulated flowsUnregulated flows

Lake Tana

Abbay (Blue Nile)

Tis Issat Falls

Tis Abbay HP plants

116Koga

Gilgel Abbay

270Andassa

1925Megech176

Ribb216

246

Gumara

Intermediate flow

2442180

1783

1784

1785

1786

1787

1788

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35

La

ke

leve

l (m

as

l)

YearNatural FDS with MMF FDS with VEF

Evaluating upstream-downstream interactions

Lake TanaImpact of dam/irrigation development on lake levels and

Implications for:• Environment• Non-ag sectors (e.g.

hydropower) • Livelihoods

Cumulative impacts

Rive

rine c

harac

terist

ic

Headwaters Lower Reaches

Rive

rine c

hara

cteris

tic

Headwaters Lower Reaches

DD

DD

Need to think about cumulative impacts in space and time

Need methods where these can be quickly determined

5. Pay attention to the political economy of policy selection

Hydrological/Resource methods - identify the costs, benefits and risks (for whom and when) associated with particular courses of action.

To be useful findings must be fed into decision-making processes.

Must think about how results are presented and to whom and when.

Thank you

Finding solutions: think out of the box

Current situation –wet season

Current situation

With managed aquifer recharge

Chao Phraya Basin Desk Study

• MAF = 12,248 Mm3y-1

• 3,300 Mm3y-1 discharge to sea harvestable

• Cost <$1 billion

• Additional 270,000 ha of irrigation

• $150 My-1 income to smallholder farmers

• No precidents. Technical studies; studies of institutional arrangements

Harvest the floods: the subsurface solution

Aim: maximizing productivity/benefits

Natural Basin Increasingly modified Basin

Benefits from natural components

Benefits from modified basin components

Sum of benefits

Total productivity (i.e. overall benefits) All change needs to be

considered in relation ecosystem services and trade-offs