Water Resources & Strategic Planning for the · PDF fileWater Resources & Strategic Planning for the Future ... • informs the Strategic Business Plan ... • impact of climate change

Water Resources & Strategic Planning for the FutureJackie TurnerOperational AnalystSouth West Water

Contents• Introduction

• Water Resources in the SWW Region

• Demand in the SWW Region

• Climate Change Impacts

• Maintaining the Supply-Demand Balance

• East Devon New Growth Point Water Cycle Study

Introduction (1)Water Strategy Section, South West Water (SWW)

• A key focus is Strategic Water Resources Planning

• A key output is the Water Resources Plan (WRP)(http://www.southwestwater.co.uk/index.cfm?articleid=1556)• shows how SWW intends to maintain the supply-demand

balance over the next 25 years• informs the Strategic Business Plan (SBP), and vice versa

• SBP focuses on next 5 year funding period

• Water Act 2003 – water companies have a statutory requirement to prepare a WRP every 5 years

Introduction (2)Water utilities need to plan to be able to maintain water supplies in a severe drought. To do this, need to:

• Understand current demand and resource availability

• Robustly forecast future “dry” year• demand• raw water availability

• Identify shortfalls between demand and supply over the forecast period

• Propose options to overcome shortfalls by• reducing demand, increasing supply, or both







The SWW Region –Sub-Regions (1)For operational and strategic purposes, the SWW Region is split into sub-regions

• Discrete parishes are grouped into “Water Into Supply” (WIS) Zones

• Discrete WIS Zones are grouped into “Resource Zones”• Largest possible zone in which all resources, including external

transfers, can be shared (i.e. the zone in which all customers experience the same risk of supply failure from a resource shortfall)

• SWW refers to them as Strategic Supply Areas (SSAs)

The SWW Region –Sub-Regions (2)

WimbleballSSA

RoadfordSSA

CollifordSSA

The SWW Region –Water Resources2008/09 - supplied ~425 million litres per day (Ml/d)

• Reservoirs ~ 45%• River abstractions ~ 45%• Springs & boreholes ~ 10%

To• 1.6 million residents• 8 million visitors

Using• 32 Water Treatment Works (WTWs)

The SWW Region –Reservoir Storage

3 large strategic reservoirs• Roadford, Colliford, Wimbleball• 75% of total reservoir storage

15 smaller local reservoirs

Each strategic reservoir• serves a large region• provides back-up to smaller, local

resources during dry periods

RoadfordColliford

WimbleballStithiansBurrator

SiblybackMeldon

ParkKen/Tot/TrenFernworthy

WistlandpoundUpper Tamar

AvonArgalDrift

CrowdyVenfordCollege

34500

28540

21320

4967

4210

3182

3020

2183

2011

1765

1550

1477

1313

1302

1200

1022

740

246

0 10000 20000 30000 40000

Net Capacity (Ml)

1979 - Wimbleball 21,320 Ml

EXETER

PLYMOUTHNEWQUAY

TRURO

ST AUSTELL

BODMIN

OKEHAMPTON

LAUNCESTON

BARNSTAPLE

BIDEFORD

TIVERTON

.

Wimbleball

To Wessex Water

1983 - Colliford 28,540 Ml

EXETER

PLYMOUTHNEWQUAY

TRURO

ST AUSTELL

BODMIN

OKEHAMPTON

LAUNCESTON

BARNSTAPLE

BIDEFORD

TIVERTON

.

Wimbleball

To Wessex Water

Colliford

1989 - Roadford 34,500 Ml

EXETER

PLYMOUTHNEWQUAY

TRURO

ST AUSTELL

BODMIN

OKEHAMPTON

LAUNCESTON

BARNSTAPLE

BIDEFORD

TIVERTON

.

Wimbleball

To Wessex Water

Colliford

Roadford

SWW Water Resources ModellingNeed to take into account:• Water availability

• abstraction licences• river flows• climate change

• Resource network• WTW min/max outputs• WPS capacities• pipe capacities• costs

• Demand• average demand• summer peaks• climate change







Demand for Water in the SWW RegionCharacteristics of Water Demand in the SWW Region:

• High population growth

• One of the highest in the country

• High peak demands

• 500,000 visitors in peak week

• Low industrial/commercial demand

Components of Total DemandTotal demand comprises the following components:

• household demand• non-household demand• leakage• distribution system operational use• water taken unbilled (legally and illegally)

Reported each year in the June Return.

All need to be considered when forecasting possible future demand.

Total Demand Forecasts

200

300

400

500

600

1977

/78

1980

/81

1983

/84

1986

/87

1989

/90

1992

/93

1995

/96

1998

/99

2001

/02

2004

/05

2007

/08

2010

/11

2013

/14

2016

/17

2019

/20

2022

/23

2025

/26

2028

/29

2031

/32

2034

/35

Dem

and

(Ml/d

)

200

300

400

500

600

Dem

and

(Ml/d

)

Historic'Normal Year' Forecast'Dry Year' Forecast

Household Demand Forecasts (1) –Factors Affecting Demand

• population and housing projections

• per capita consumption

• meter optant rates

• climate change impacts on demand

The main factors affecting household demand are:

Household Demand Forecasts (2) –Population Forecasts• Provided by demographic consultant

• Based on• district & city council development plans• latest housing growth scenario from South West Regional

Assembly

• Represent ‘best estimate’ figures as at October 2008

• Provided by parish to 2016 and by district thereafter• Post-2016, SWW has distributed district forecasts amongst

constituent parishes (using 2016 population ratios)

Household Population Forecasts

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

1977

/78

1980

/81

1983

/84

1986

/87

1989

/90

1992

/93

1995

/96

1998

/99

2001

/02

2004

/05

2007

/08

2010

/11

2013

/14

2016

/17

2019

/20

2022

/23

2025

/26

2028

/29

2031

/32

2034

/35

Popu

latio

n (m

illio

ns)

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

Popu

latio

n (m

illio

ns)

HistoricForecast

Household Demand Forecasts (3) –Per Capita Consumption (PCC)• Produce actual “base year” PCC estimates

• unmeasured and measured households separately• micro-component analysis (ownership, frequency of use, volume per use)

• SODWaC questionnaire analysis• survey of academic, government, industrial, Consumer Association research

• Produce “normal” and “dry” year estimates for base year• Produce annual forecasts at micro-component level

• “normal” and “dry” year• changes in ownership, frequency of use, volume per use• savings from water efficiency measures• climate change effects• include effects of increased water efficiency in new homes likely to result from the

Code for Sustainable Homes and future changes to Building Regulations

PCC Forecasts(measured & unmeasured combined)

120

130

140

150

160

170

18020

07/0

820

08/0

920

09/1

020

10/1

120

11/1

220

12/1

320

13/1

420

14/1

520

15/1

620

16/1

720

17/1

820

18/1

920

19/2

020

20/2

120

21/2

220

22/2

320

23/2

420

24/2

520

25/2

620

26/2

720

27/2

820

28/2

920

29/3

020

30/3

120

31/3

220

32/3

320

33/3

420

34/3

5

PCC

(litr

es p

er p

erso

n pe

r day

)

120

130

140

150

160

170

180

PCC

(litr

es p

er p

erso

n pe

r day

)

Dry yearDry year inc. water efficiency projects and tariff changeNormal yearNormal year inc. water efficiency projects and tariff change

Non-Household Demand Forecasts (1)• Produced by industry type• Include forecasts of water efficiency over time• Based on macroeconomic forecast of employment and

economic output within the SWW Region for the forecast period (Plymouth Business School)

• incorporates longer term structural trends in the economy and employment by industry

• SWW used knowledge of historic water use by industry to produce forecasts of likely water use for this economic forecast

Non-Household Demand Forecasts (2)

60

70

80

90

100

110

120

1977

/78

1980

/81

1983

/84

1986

/87

1989

/90

1992

/93

1995

/96

1998

/99

2001

/02

2004

/05

2007

/08

2010

/11

2013

/14

2016

/17

2019

/20

2022

/23

2025

/26

2028

/29

2031

/32

2034

/35

Dem

and

(Ml/d

)

60

70

80

90

100

110

120

Dem

and

(Ml/d

)

Historic DemandForecast 'Dry Year' DemandForecast 'Normal Year' Demand

Water Efficiency SchemesSWW is promoting three water efficiency schemes for 2010-2015:

• Domestic Water Efficiency Project• Small & Medium Enterprise Project• Water Efficiency at Waste Water Treatment Works

These build on existing household and non-household water efficiency activities.

New TariffFor 2015-16 SWW aims to introduce new tariffs

• currently trialling a rising block tariff• estimate new tariff will reduce measured demand by

around 5%

Not a water efficiency scheme – but will hopefully encourage more efficient use







Climate ChangeConsider climate change impacts on

• demand• household• non-household

• supply• surface water• groundwater

Climate Change Impacts on Demand (SWW Region)CCDeW: Climate Change and the Demand For Water (2003)• Report uses UKCIP02 medium-high scenario & world markets socio-

economic scenario• Forecasts household demand to increase by 1.4% in the SWW

Region due to climate change by 2024/25• SWW divided the increase between micro-components most

sensitive to climate change (proportions suggested in the report):• garden watering 25%• personal washing 70%• other (clothes washing) 5%

• Forecasts non-household demand to increase by 3.2% by 2024/25 and 4.3% in 2034/35

• SWW scaled these increases linearly between intervening years

Climate Change Impacts on River Flows (SWW Region)Effect of Climate Change on River Flows and Groundwater Recharge– guidelines for resource assessment and UKWIR06 Scenarios(UKWIR 2007)

• tables of predicted percentage change in mean monthly runoff due to climate change effects (relative to 1961-1990 baseline)

• different scenarios (“dry”, “mean”, “wet”)• tables for “study catchments” and “regional”• methodology for applying flow factors to historic river flow data

• SWW adjusted historic daily mean flow data for each river by theclimate change factors to create flow sequences characteristic of possible conditions in 2025

• SWW modelled the effects of these new flows on Water Available for Use (WAFU)

Climate Change Impacts on Groundwater (SWW Region)Effect of Climate Change on River Flows and Groundwater Recharge– guidelines for resource assessment and UKWIR06 Scenarios (UKWIR 2007)

• reassessed groundwater source deployable outputs in 2007• individual constraints on output were identified

• if source performance and groundwater level are constraints, climate change may result in reduced deployable output

• some sites identified as being at risk due to predicted groundwater level fall and/or sea level rise

Climate Change Impact on WAFU (SWW Region)

Notes:• Although climate change is forecast to reduce WAFU in all SSAs,

infrastructure constraints may influence this impact.• Uncertainties in climate change forecasts are accounted for within target

headroom, using wet and dry climate change scenarios.

-0.59%-1.86%-1.53%Estimated change in WAFU

Wimbleball SSARoadford SSAColliford SSAResource Zone

Forecast impact of climate change on WAFU by mid 2020s under the mean climate change scenario:







Accounting for Uncertainty: HeadroomHeadroom:“The buffer between supply and demand to cater for specified uncertainties in the overall supply-demand balance to help a water company achieve its chosen level of service.”A Practical Method for Converting Uncertainty into Headroom (98/WR/13/1)

Target headroom:“The threshold of minimum acceptable headroom, which would trigger the need for water management options to increase water available for use or decrease demand”.Water Resources Planning Guideline, Environment Agency, Nov 2008

Target Headroom – SWW RegionSWW followed methodology given in UKWIR report “An Improved Method for Assessing Headroom” (Ref No 02/WR/13/2)

• Headroom considered for each SSA separately

• Calculations consider the following uncertainties• supply related:

• accuracy of supply-side data• impact of climate change on water availability• output from new resource developments

• demand related:• accuracy of sub-component data• demand forecasts• impact of climate change on demand• outcome from demand management measures

Maintaining the Supply/Demand Balance -Colliford SSA (WRP09)

Colliford Strategic Supply AreaFinal Supply - Demand Balance

120

130

140

150

160

170

180

190

200

210

220

2007

/08

2008

/09

2009

/10

2010

/11

2011

/12

2012

/13

2013

/14

2014

/15

2015

/16

2016

/17

2017

/18

2018

/19

2019

/20

2020

/21

2021

/22

2022

/23

2023

/24

2024

/25

2025

/26

2026

/27

2027

/28

2028

/29

2029

/30

2030

/31

2031

/32

2032

/33

2033

/34

2034

/35

Dem

and

(Ml/d

)

120

130

140

150

160

170

180

190

200

210

220

Wat

er A

vaila

ble

for U

se (M

l/d)

Water Available for Use (WAFU) Planned Scheme / Non-WRP Supply-Demand Option

Forecast Demand + Target Headroom (excl. water efficiency options) Forecast 'Dry Year' Demand (excl. water efficiency options)

Forecast Demand + Target Headroom Forecast 'Dry Year' Demand

Significant investment at Stithians WTW for capital maintenance & operational efficiency reasons.

Park & Stannon Lakes operational, Lizard distribution area improvements, Restormel max output 100 Ml/d.

Demand reduction due to new tariffs

Maintaining the Supply/Demand Balance -Roadford SSA (WRP09)

Roadford Strategic Supply AreaFinal Supply - Demand Balance

200

210

220

230

240

250

260

270

280

290

300

2007

/08

2008

/09

2009

/10

2010

/11

2011

/12

2012

/13

2013

/14

2014

/15

2015

/16

2016

/17

2017

/18

2018

/19

2019

/20

2020

/21

2021

/22

2022

/23

2023

/24

2024

/25

2025

/26

2026

/27

2027

/28

2028

/29

2029

/30

2030

/31

2031

/32

2032

/33

2033

/34

2034

/35

Dem

and

(Ml/d

)

200

210

220

230

240

250

260

270

280

290

300

Wat

er A

vaila

ble

for U

se (M

l/d)

Water Available for Use (WAFU) Planned Scheme / Non-WRP Supply-Demand OptionSustainability Reduction Forecast 'Dry Year' Demand (excl. water efficiency options)Forecast Demand + Target Headroom (excl. water efficiency options) Forecast 'Dry Year' DemandForecast Demand + Target Headroom

Lopwell Sustainability Reduction

Avon / Littlehempston improvements allowing benefit of AMP4 schemes to be realised

4.8 Ml/d Sustainability Reduction


Maintaining the Supply/Demand Balance -Wimbleball SSA (WRP09)

Wimbleball Strategic Supply AreaFinal Supply - Demand Balance

50

60

70

80

90

100

110

120

130

140

150

2007

/08

2008

/09

2009

/10

2010

/11

2011

/12

2012

/13

2013

/14

2014

/15

2015

/16

2016

/17

2017

/18

2018

/19

2019

/20

2020

/21

2021

/22

2022

/23

2023

/24

2024

/25

2025

/26

2026

/27

2027

/28

2028

/29

2029

/30

2030

/31

2031

/32

2032

/33

2033

/34

2034

/35

Dem

and

(Ml/d

)

50

60

70

80

90

100

110

120

130

140

150

Wat

er A

vaila

ble

for U

se (M

l/d)

Water Available for Use (WAFU) Planned Scheme / Non-WRP Supply-Demand OptionForecast 'Dry Year' Demand (excl. water efficiency options) Forecast Demand + Target Headroom (excl. water efficiency options)Forecast 'Dry Year' Demand Forecast Demand + Target Headroom








East Devon New Growth Point Water Cycle Study• WRP09 population forecasts are in line with the latest RSS

projections

• Enough raw water available in Wimbleball SSA to supply projected growth until at least 2035

• May be local treatment / infrastructure constraints• may be aware of existing problems at a site• surveys may be required to identify constraints

• currently undertaken only if specific sites likely to be developed

• improvements would be made if required• possible funding issues

Any Questions?

Documents

Water Resources & Strategic Planning for the · PDF fileWater Resources & Strategic Planning for the Future ... • informs the Strategic Business Plan ... • impact of climate change