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Towards a world ofcities in2050

Background report to the UN-Habitat Global Report

An outlook on water-related challenges


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Towards a world of cities in 2050


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Towards a world of cities in 2050An outlook on water-related challenges

Background repor o he UN-Habia Global Repor

In collaboraion wih

ARCADIS Sheler programUNESCO-IHEVU Universiy Amserdam


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This publicaion can be downloaded rom: ww w.pbl.nl/en.

Pars o his publicaion may be reproduced, providing he source is saed, in he orm: Ligvoe W. e al. (2014), Towards a world of

cities in 2050 an outlook on water-related challenges. Background report to the UN-Habitat Global Report, The Hague: PBL Neherlands

Environmenal Assessmen Agency.

PBL Neherlands Environmenal Assessmen Agency is he naional insiue or srae gic policy analyses in he fie lds o heenvironmen, naure and spaial planning. We conribue o improving he qualiy o poliical and adminisraive decision-making,

by conducing oulook sudies, analyses and evaluaions in which an inegraed approach is considered paramoun. Policy relevance

is he prime concern in all our sudies. We conduc solicied and unsolicied research ha is b oh independen and always

scienifically sound.

Towards a world of ciies in 2050 an oulook on waer-relaed challenges

Background repor o he UN-Habia Global Repor

PBL Neherlands Environmenal Assessmen Agency

ISBN: 978-94-91506-75-8PBL publicaion number: 1325This sudy was conduced a he reques o UN-Habia,Nairobi, Kenya.

Auhors

Willem Ligvoe & Henk Hilderink (ediors),Arno Bouwman, Peer van Puijenbroek, Paul Lucas,

Maria Wimer

Corresponding auhor

[email protected]

ConribuionsJoos Knoop, Hans Visser (PBL), Philip Ward, Jeroen Aers,Ralph Lasage (VU Universiy Amserdam),Assela Pahirana, Peer van der Seen (UNESCO IHE),Ber Smolders, Daan Solker, Floris Zevenbergen(ARCADIS Sheler program)

English-language ediing

Serena Lyon, Second Soul

Graphics

PBL Beeldredacie

Producion coordinaion

PBL Publishers

Layou

Texceera


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ContentsSummary 6

1 Inroducion 12

1.1 Main messages 121.2 Conex: owards a world o ciies 121.3 Fourh UN-Habia repor 121.4 OECD Environmenal Oulook-based approach 131.5 Concepual ramework 13

1.6 Waer-relaed policy opions 141.7 This repor 14

2 Baseline Scenario 16

2.1 Main messages 162.2 Inroducion 162.3 Main drivers: demography, urbanisaion and economy 162.4 Energy, land and climae in relaion o waer 192.5 Waer demand and waer sress 21

3 Waer supply and saniaion 22

3.1 Main messages 22

3.2 Inroducion 223.3 Modelling waer supply and saniaion and associaed healh impacs 243.4 Trends and projecion 263.5 Impacs on human healh 263.6 Policy opions 26

4 Waer qualiy: nuriens in surface waer 30

4.1 Main messages 304.2 Inroducion 304.3 Modelling emissions rom urban areas o surace waer 314.4 Trends and projecion 324.5 Negaive effecs o europhicaion on ciies and coasal areas 354.6 Policy opions 37

5 Flood risks 40

5.1 Main messages 405.2 Inroducion 405.3 Modelling flood risks 425.4 Trends and projecion 445.5 Cos o reducing flood risk 495.6 Inequaliy and flood risks 525.7 Policy opions 53

6 Concluding remarks 60

6.1 Oulook on waer-relaed challenges in ciies: main findings 60

6.2 Towards inegraed urban developmen 61

References 64

Appendix 70


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6

| Towards a world o ciies in 2050

Summary

An increasing population and expanding cities are

challenging water managementAround 50% o he worlds populaion currenly lives inan urban environmen, and his percenage is expecedo increase over he coming decades. Under he BaselineScenario used in his sudy, major changes in socio-economic and environmenal rends are projeced. Theworlds populaion is expeced o grow by more han2 billion people, o 9.2 billion by 2050. Mos o hisgrowh will ake place in developing counries and, morespecifically, in he urban areas here. By 2050, around70% o he worlds populaion is expeced o live in anurban environmen (Figure 1).

As a resul, demand or waer, ood and energy willincrease and is expeced o pu pressure on heenvironmen. Climae change, wih higher averageemperaures and changing precipiaion paterns,combined wih increasing compeiion or available waerresources, may resul in subsanial increases in henumber o people living under severe waer sress.Wihou major policy changes, subsanial improvemensin waer managemen and echniques as well as smarspaial developmen, his rend is likely o affec qualiyo lie; or example, hrough increasing impacs onhuman healh.

Access o clean drinking waer and proecion againsflooding is undamenal o human well-being. The waermanagemen ha is needed o mee hose needs poses a

major and growing challenge especially in he as

growing ciies in developing counries.

Access to water is expected to improve; sanitationto lag behind. The cost-benefit ratio of investmentsin water supply and sanitation will be positive, withrespect to human healthIn he coming years, subsanial progress may beexpeced in he access o sae drinking waer andimproved saniaion. As a resul o income increases(which make a higher sandard o living more affordable)and increasing urbanisaion (which enables morecos-efficien higher coverage raes), he MillenniumDevelopmen Goals ha arge waer supply have already

been atained, globally, and urher progress is projeced.Wih respec o access o saniaion, however, currendevelopmens show ha many counries sill lag behind,paricularly in sub-Saharan Arica, alhough here uureprogress also is projeced.

Despie his progress, policy challenges remain. Firs oall, he Millennium Developmen Goals only ocus onhalvinghe number o people wihou access o improvedsaniaion. Secondly, he MDGs also only aim o achieveimproveddrinking waer services, which even hen wouldsill be ar rom hose ensuring a decen sandard o living

(i.e. in he orm o household connecions). Thirdly,achieving coverage sill does no necessarily mean haconnecions are sae. For example, increasing waersress may affec waer qualiy, causing negaive healhimpacs.

UN-Habia will publish heir fourh global repor on waer and saniaion in ciies. A heir

reques, PBL Neherlands Environmenal Assessmen Agency has conduced a sudy on fuure

rends and challenges as inpu for his global repor. Topics addressed are waer supply and

saniaion, nurien emissions and waer qualiy, and flood risks.


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7Summary |

Figure 1

1970 1990 2010 2030 2050

0

2

4

6

8

10

billion people

Source: UN DESA (2009; 2010)

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Middle East and North Africa

Sub-Saharan Africa

South Asia

Latin America and the Caribbean

Total population

1970 1990 2010 2030 2050

0

2

4

6

8

10

billion people

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Urban population

East Asia and Pacific

Russian region and Central Asia

Developed countries

Population and urbanisation under the Baseline Scenario

Baseline Scenario for population and urbanisation up to 2050, used in this study for e xploring future trends and challenges with respect to water andsanitation in cities.

Figure 2

Developed countries





South Asia

Sub-Saharan Africa

0 100 200 300 400

million people

Source: Hilderink et al. (2008)

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1990

2010

2030

2050

Urban population without improved sanitation

Population without access to improved sanitation in urban areas, 1990, 2010, 2030 and 2050


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8 | Towards a world o ciies in 2050

Figure 3

1970 1990 2010 2030 2050

0

1

2

3

4

5

million tonnes N/year

Source: OECD (2012)

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South Asia

Sub-Saharan Africa

Developed countries

Nitrogen emissions

1970 1990 2010 2030 2050

0

200

400

600

800

thousand tonnes P/year

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Phosphorus emissions

Household nutrient emissions to surface water




Trends in household nitrogen and phosphorus emissions to surface water

Invesmens in waer supply and saniaion are projecedo have a posiive cos-benefi raio, in erms o healhimpacs and heir valuaion. Aiming or universalcoverage by 2050, an annual 70,000 deahs could beavoided in sub-Saharan Arica alone.

Without action, nutrient emissions will increase.Improved sanitation requires improved waste-

water treatment.A cenury ago, he dominan pahway or nuriens was

heir reuse in agriculure; oday, he dominan pahwayis or hem o end up in surace waer. Coninuedinvesmens in wase-waer reamen in developedcounries are expeced o sabilise and resore suracewaer qualiy. The qualiy o surace waer in ohercounries, however, is expeced o deeriorae beween2010 and 2050. Under he Baseline Scenario, nurienemissions in Asia and Arica are projeced o doubleor riple over nex 40 years (Figure 3). This will lead oincreased europhicaion and biodiversiy loss, as well asan increased hrea o drinking waer, fishery, aquaculureand ourism ecosysem services.

Higher saniaion coverage raes could have a direcposiive effec on human healh, bu may also haveadverse effecs on he environmen i hese improvedsaniaion connecions are no combined wih wase-

waer reamen. Populaion growh combined wihhigher income levels will urher increase nurienemissions rom ciies. This poses an increased risk o hequaliy o drinking waer and ood producion in andaround ciies.

I is increasingly recognised ha he urban waer sysemis bes designed, planned and managed in an inegraedmanner. Wase-waer reamen should be par o alarger sysem, aimed a delivering services o urban

dwellers wihou compromising on susainabiliy.Opions or reducing emission levels and achieving amore susainable ciy include beter sewage and wase-waer reamen sysems and he reuse o nuriens inagriculure.

There are many examples o successul large-scaledevelopmens in saniaion, sewage and wase-waerreamen sysems in ciies. New echnologies andincenives or local reuse o nuriens rom sewage sludgemay avour comparaively low-cos decenralised opionswhen coss or large-scale sysems are oo high. For local

communiies in rural areas, on-sie saniaion and betermanagemen o aecal sludge may be ineresing opions.

In ransboundary cachmen areas, agreemens beweencounries are necessary o improve waer qualiy and


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9Summary |

preven excessive polluion o coasal waers, resuling inlarge-scale fish kills and algae blooms.

By 2050, 15% of the global population will live inflood-prone areas. Integrating flood risk strategiesin urban development may strongly reduce the lossof lives as well as economic losses

Over he pas 30 years (19802010), on average, closeo 90 million people were affeced by flood disasers,and each year around 5,000 people were killed. Averageannual global losses due o floods over his periodamouned o almos USD 20 billion. Floods make up

over 40% o all weaher-relaed disasers, affec hemos people and are he second-larges naural causeo economic loss. No climae change signal has beendeeced in flood disasers in he hisorical rend up o2010. Populaion growh and economic developmenwere he dominan drivers o increases in he numbers opeople affeced and economic losses due o coasal and

river floods.

Leaving aside he effecs o climae change, he numbero people living in flood-prone areas is esimaed o be1.3 billion by 2050, or 15% o he global populaion. This is

Figure 4

2010 2050

0

20

40

60

80

million people

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World

2010 2050

0

2

4

6

8

million people

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Developed countries

2010 2050

0

1

2

3

4

million people

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2010 2050

0

5

10

15

20

25

million people

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South Asia

Annual exposed population to floods

2010 2050

0

5

10

15

20

25

million people

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2010 2050

0

1

2

3

4

5

million people

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2010 2050

0

2

4

6

8

million people

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Sub-Saharan Africa

2010 2050

0.0

0.3

0.6

0.9

1.2

1.5

million people

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Protection standard 1:10

Rural

Urban


Rural

Urban


Urban

Russian region and Central Asia Middle East and North Africa


Source: PBL

Comparison of urban and rural populations annual exposure to floods, in 2010 and in 2050 applying different protection standards. Note the difference

between the y-axis scales


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an increase o 0.3 billion compared wih he presensiuaion. As urban areas expand, hundreds o rillions odollars in inrasrucure, indusrial and office buildingsand homes will be increasingly a risk rom river andcoasal flooding paricularly in Asia. Under he BaselineScenario, by 2050, here could be 670 ciies o 500,000inhabians or more, and 88 o which will have more han5 million inhabians. O hese 88 ciies, 50% will rankhighes wih respec o vulnerabiliy o flooding, basedon he size o he populaion exposed and GDP percapia. The mos vulnerable megaciies could be Dhaka,Kolkaa, Shanghai, Mumbai, Jakara, Bangkok andHoh Chi Minh Ciy.

There is a wide range o measures available o reduceflood risk. Figure 4 shows boh he srong increases inannual exposed populaion by 2050 especially in heurban areas and he poenially large effecs oimproving flood proecion. Given he poenially largeeffec o hese measures, i is imporan or ciies andcounries o pay serious atenion o he developmen oadequae flood risk sraegies. The coss o adequaeflood proecion measures may no necessarily be high,and high concenraions o asses and people in ciiesmay provide an opporuniy or highly cos-effecive

flood proecion sraegies, srongly reducing boh losso lives and economic losses

Flood vulnerabiliy is unevenly disribued wihin ciiesand, ofen, he poores suffer disproporionally. Wihinhe conex o environmenal jusice, public auhoriiesace he challenge o improving he level o proecionagains flooding wihou increasing he inequaliy wihrespec o flood risk.

Towards integration of water-related challenges inurban developmentThe findings o his repor show ha, in he coming

decades, major changes and challenges lie ahead. Despieposiive developmens policy challenges remain; orexample, regarding he healh impacs o improvedwaer supply and saniaion. Each chaper in his reporidenifies poenially successul policy opions ha wouldresul in an improvemen regarding he issues a hand.However, here are also imporan inerconnecionsbeween he various waer issues. For example,invesing in saniaion wihou adequae invesmenin wase-waer reamen would, in ac, deerioraehe waer qualiy in rivers, lakes and coasal waers. Inurn, poorer waer qualiy could impac human healh.

Also, despie sufficien invesmen in waer supply,saniaion and wase-waer reamen inrasrucure,urban expansion which will ake place paricularly indeveloping counries could sill be a risk i flooding isno aken ino accoun. This calls or a more inegraed

approach in urban developmen, in which hese aspecsare considered in combinaion. A promising concep haallows or such an inegraed approach is ha o smarciies. Applying such a concep o he waer challengeso he uure (smar waer) may help creae ciies hause waer and energy more efficienly, reuse waer andwase-waer reamen producs (such as nuriens), andachieve he smar and climae-proo design o sewageand wase-waer reamen sysems, urban developmenplans and green and blue inrasrucure, prevening urbanflooding and reducing flood risks.Exising and newly developed ciy neworks areimporan plaorms o exchange knowledge, undersand

he common challenges and share bes pracices andinnovaions ha can suppor ciies in heir economic,spaial and social developmen sraegies.


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12

ONE


IntroductionONE

1.1 Main messages

UN-Habia will publish a repor eniled Globalrepor on waer and saniaion in ciies o he uure(working ile). PBL Neherlands EnvironmenalAssessmen Agency (PBL) has been commissioned byUN-Habia o produce an inpu repor or his globalrepor.

This inpu repor provides uure projecions orelevan issues relaing o waer and saniaion,making use o PBLs global modelling suie. PBL has

a proven rack record in producing inegraedassessmens wih a srong modelling componen.Given he limied resources available, he projecionshave been based on available scenario sudies, suchas he OECD Environmenal Oulook, Roads rom Rio,and sudies commissioned by he Duch Minisry oForeign Affairs.

Based on an invenory o PBL sudies, he ollowingopics were included: 1) waer supply and saniaion,2) nuriens in surace waer and wasewaerreamen, and 3) flood risks.

1.2 Context: towards a world of cities

Around 50% o he worlds populaion currenly lives inan urban environmen, and his percenage is expecedo increase in he coming decades. A growing urbanpopulaion provides boh opporuniies and challenges.Opporuniies, because a high concenraion o peoplemakes i easier o supply a larger par o he populaionwih adequae healh and waer services, as well asimprove he efficiency o energy, waer and land use.Growing ciies will also provide opporuniies orimplemening and disseminaing new knowledge and

echnologies relaing o urban planning and buildingdesign, as well as he developmen o raffic, energyand waer service sysems (Glaeser, 2011).

A he same ime challenges arise abou how o proeche environmenal qualiy in and around hese as-growing ciies. To connec more people o a seweragesysem is one imporan sep, bu wihou properwasewaer reamen he receiving rivers and coasalzones will become pollued wih excess nuriens, heavymeals and oher healh-hreaening subsances. Hisoryshows ha ailure o acknowledge his resuls in a declinein environmenal qualiy. Consequenly, poor air qualiy,waer qualiy and spaial qualiy will srongly reduce hequaliy o he living environmen and healh o he ciy

populaion. Very ofen, he effecs o environmenalpolluion, poor waer availabiliy and poor healhservices, and he resuling losses in healh and qualiyo living are unequally disribued among he urbanpopulaion, wih he poor ofen suffering he mos (MEA,2005). Segregaion and inequaliy in ciies is o all imesand all regions (Nighingale, 2012), bu in many ciies especially in developing counries slum dwellersnumber more han 50% o he populaion and have litleor no access o sheler, waer and saniaion (UN-Habia,2005). Reducing inequaliy and povery in ciies on hepah owards 2050 may well be one o he majorchallenges o he uure.

Climae change orms an addiional challenge or heseurban areas (IPCC, 2013). Temperaure rises, he increa-sing requency and inensiy o rainall or drough, risingsea levels and changing river discharges need o beaddressed while developing new urban areas andresrucuring he old.

1.3 Fourth UN-Habitat report

UN-Habia will publish a repor eniled Global reporon waer and saniaion in ciies o he uure (working

ile). This repor will be he ourh repor on his opic.Following he mandae o he 19h Governing Council,resoluion 19/6, UN-Habia has made Waer andsaniaion in he worlds ciies a recurren publicaion,


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131 Inroducion |

ONE

published every hree years. In 2003, UN-Habiapublished he firs ediion eniled Waer and saniaion

in he worlds ciies: local acion or global goals. Thesecond repor, Waer and saniaion in he worlds ciies:meeing developmen goals in small urban cenreswas published in 2006, and he hird repor, Waer andsaniaion in he worlds ciies: solid wase managemenin he worlds ciies was published in 2010. This reporocused on he managemen o solid wase and bio-solids in urban cenres. A orward-looking perspecivewill be aken in he ourh repor in 2014. I is wih regardso such a orward-looking perspecive ha PBL can makea paricularly useul conribuion, based on recen PBLscenario sudies ha include he OECD EnvironmenalOulook, Roads rom Rio, and oher projecs or he

Duch Minisry o Foreign Affairs. I is or his reason haUN-Habia has asked PBL o wrie a background reporo be used an inpu or he upcoming UN-Habia repor.

1.4 OECD Environmental Outlook-

based approach

Based on an invenory o PBL sudies, he ollowing opicswere idenified as being o ineres: 1) waer supply andsaniaion, 2) nuriens in surace waer and wasewaer

reamen, and 3) flooding risks. The approach akenin his repor is based on recen PBL scenario sudies.One o he mos relevan sudies used is he OECDEnvironmenal Oulook, which includes a hemaic waer

chaper (OECD, 2012). The OECD Environmenal Oulookcovers all hree opics a he global level, while also

allowing differeniaion by urban and rural populaionsor cerain regions. Anoher relevan sudy is he Roadsrom Rio repor (PBL, 2012), which ocused on poenialpolicy pahways or achieving globally agreed policyarges. Choosing an exising scenario sudy has headvanage ha some pars o he work including hecapaciy-inensive ones have already been done. Iobviously also has is disadvanages, as he selecion oissues canno be alered, he ime horizon and unis oanalysis (i.e. regional breakdown) are already fixed, andhe scenario logics, or example a baseline approach wiha single incarnaion o he uure, are deermined wihouhaving his paricular applicaion in mind. However, given

he opics covered in he OECD Environmenal Oulook,he relaively deailed uni o analysis o he simulaionmodels used and he ime horizon o 2050, i wasconsidered o provide a sound basis or his sudy.

1.5 Conceptual framework

The ollowing concepual ramework was used oposiion and analyse he waer-relaed issues in ciies.This ramework (see Figure 1.1) shows he mos relevanconexual socio-economic and environmenal acors

relaed o various aspecs o waer addressed in hisrepor. These are demand, availabiliy, use and impacs.The differen policies ha may influence hese waeraspecs are also shown. These policies are waer resource

Figure 1.1Conceptual framework of water-related issues

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Socio-economic factors Environmental factors

Climate change, agricultural

productivity, land use and land cover

Population, economic growth,

urbanisation

Water demand

Agriculture

Industry

Domestic

Water availability

Ground water

Surface water

Precipitation

Variability

Water use

Coverage of water supply and sanitation

Waste-water treatment

Impacts

Health impacts

Water stress

Water quality

Flood risks

Policies:

Water

resource

management

Access to water

sanitation and

hygiene

Waste-water

management and

water quality

Flood risk

management


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ONE

managemen, access o waer supply and saniaion,wasewaer managemen and flood risk managemen.

1.6 Water-related policy options

There are many ways o posiion waer-relaed policies inhe urban environmen, a various scales, and wih manyacors involved in he planning and implemenaion.

This requires close cooperaion beween he varioussocial acors and a clear division o responsibiliiesbeween governmen, public paries, privae companiesand he general public. Figure 1.2 provides an overviewo he relaionships beween he various scales andassociaed policy opions and acors, using adapaionmeasures as an example. In his repor, we ocus onpolicy inervenions ha aim o improve waer supplyand saniaion and waer qualiy, and ha anicipae andlower flood-relaed risks.

1.7 This report

The ouline o his repor is as ollows. The BaselineScenario is described in Chaper 2. This includes hemos imporan socio-economic and environmenaldrivers (such as populaion, urbanisaion and climaechange). Oher aspecs o waer ha are no specificallycovered by oher chapers, such as waer demand andwaer sress, are also presened in Chaper 2. Drinking

waer and saniaion are discussed in Chaper 3, andwaer qualiy in Chaper 4. In Chaper 5, he possibleimpac o flooding in erms o people and asses a riskis calculaed. In he final chaper, Chaper 6, he overallfindings and conclusions are presened and discussedwihin he broader conex o he concep o smar ciies.The analyses in his repor are mosly conduced a a gridlevel o 0.5 by 0.5 degrees or environmenal aspecs suchas land use and climae change, and 30 by 30 seconds orflood risks. For socio-economic aspecs such as economicgrowh, populaion and healh he analyses are carriedou or he 27 world regions and counries in he IMAGE

modelling suie (Bouwman e al., 2006). The final resulsare presened a he aggregaed level o he seven WorldBank regions (see Figure 1.3).

Figure 1.2Adaptation measures at various scales within the urban environment

Source: PBL

Buildings

Flexibility

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High

Low

Districts

City

Infrastructure

Surroundingareas

Various scales for water-related adaptation policies in the urban environment


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151 Inroducion |

ONE

Figure 1.3World Bank Regions

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l

World Bank region

Developed countries





South Asia

Sub-Saharan Africa

Source: World Bank

Regional presentation used in this report (World Bank, 2014)

Tex box 1.1 Waer and he Susainable Developmen Goals

The definiion, design and implemenaion o long-erm susainabiliy goals has aken cenre sage in heUnied Naions wih he discussion on he pos-2015 developmen agenda, as a ollow-up o he MillenniumDevelopmen Goals (MDGs), and he Susainable Developmen Goals (SDGs) ha emerged rom he 2012 UNConerence on Susainable Developmen (Rio+20). I was recognised a Rio+20 ha waer is a he core osusainable developmen, and Member Saes reconfirmed previous commimens made in he JohannesburgPlan o Implemenaion and he Millennium Declaraion, also regarding he righ o sae drinking waer andsaniaion. Furhermore, he pervasive links beween waer and oher prioriy areas were refleced in he Rio+20oucome documen.The open consulaion on waer concluded ha Waer, Saniaion and Hygiene (WASH), Waer ResourcesManagemen and Wasewaer Managemen and Waer Qualiy are all indispensable elemens or building a

waer-secure world (UN-Waer, 2013). This is also recognised in he many proposals or a pos-2015 developmenagenda, many o which inegrae he social, economic and environmenal dimensions o he waer challenge inone single goal (Griggs e al., 2013; HLP, 2013; UNGC, 2013; UNSGAB, 2013). UN-Waer (2014) builds on all heserepors and proposes a goal o secure susainable waer or all, wih five underlying arges ha address: drinking waer, saniaion and hygiene; waer resources; waer governance; waer-relaed disasers; wasewaer polluion and waer qualiy.I should be noed ha he very local naure o waer poses challenges regarding he reconciliaion o a universalagenda wih he variey o naional, local or basin-specific realiies. This repor provides insighs ino hemagniude o hese uure challenges and possible policy inervenions or achieving hese five arges.


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16

TWO


Baseline ScenarioTWO

2.1 Main messages

Under he Baseline Scenario, he world populaion isprojeced o grow by 2.2 billion beween 2010 and2050, reaching almos 9.2 billion by 2050. In he 49leas developed counries, he populaion is projecedo double in size.

In 2050, nearly 70% o he worlds populaion will livein ciies, which implies an urban populaion increaseo 2.8 billion compared wih oday. This will haveposiive economic consequences, bu may also lead

o higher environmenal pressures. World GDP is projeced o quadruple beween 2010and 2050. Beween 2010 and 2030, GDP growh willbe largely driven by he increased use o physicalcapial.

The world energy demand by 2050 is projeced o beabou 80% higher han oday; he area o agriculuralland is projeced o peak beore 2030 and declinehereafer; he area o irrigaed land is assumed oremain consan up o 2050. This later assumpionmay resul in an underesimaion o uure waersress in some regions.

By he end o he 21s cenury, he global average

emperaure is likely o be 3 C o 6 C higher hanpre-indusrial levels. Temperaure rises andprecipiaion changes will be unequallygeographically disribued.

Global waer demand is projeced o increase by 55%beween 2000 and 2050, wih sharp rises expeced inhe emerging economies. Compeiion or waerbeween urban claims and waer or irrigaion willinensiy. By 2050, 3.9 billion people over 40% ohe worlds populaion are projeced o live in riverbasins under severe waer sress.

2.2 Introduction

This chaper describes he Baseline Scenario used or heanalysis in he ollowing chapers. The scenario semsrom he hird OECD Environmenal Oulook (OECD,2012). I assumes ha no new policies are inroduced andprovides a benchmark agains which he differen policyvarians are assessed.

2.3 Main drivers: demography,

urbanisation and economy

Demographic developmentsFuure populaion growh is based on he mediumprojecion o he UN World Populaion Prospecs (UNDESA, 2009). According o his projecion, he worldpopulaion will grow by 2.2 billion beween 2010 and2050, reaching almos 9.2 billion people. Mos populaiongrowh will ake place in developing counries, and inhe 49 leas developed counries in paricular, where hepopulaion will double in size (Figure 2.1).Beween 2010 and 2050, nine counries are expeced o

accoun or hal o he worlds projeced populaionincrease. These are India, Pakisan, Nigeria, Ehiopia,he Unied Saes o America, he Democraic Republic oCongo, he Unied Republic o Tanzania, China andBangladesh (lised according o he size o heir conri-buion o global populaion growh). The populaion oArica could double by he middle o he cenury, romaround one billion in 2010 o wo billion by 2050.According o he 2012 UN World Populaion Prospecs(UN DESA, 2013), he global populaion may increase upo 9.6 billion by 2050, wih a margin o plus or minus1.3 billion in he high and low varians, meaning ha he

projecions used in he Baseline Scenario are wihin helower margin o uncerainy o his newer projecion. The2012 revision projecions are paricularly higher or Arica,wih he medium varian projecing a populaion o2.4 billion by 2050.


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UrbanisationFuure urbanisaion is based on he UN World Urbaniza-ion Prospecs (UN DESA 2010). By 2050, 2.8 billion morepeople han oday are projeced o be living in urbanareas, which is more han he oal populaion growh.In 2050, nearly 70% o he worlds populaion will livein ciies (Figures 2.1 and 2.2). The urban populaion isprojeced o be unevenly disribued around he world.In OECD counries, i is projeced o be 86% o he oalpopulaion by 2050, and in sub-Saharan Arica i is

projeced o increase rom 37% in 2010 o 60% by 2050,implying high growh raes. Growh raes are also highin urban agglomeraions in Souheas Asia. Small urbancenres o less han 0.5 million inhabians are projecedo grow more rapidly han oher urban areas.A posiive consequence o urbanisaion may be highereconomic growh because o he higher concenraion oaciviies leading o economies o scale. The provision oinrasrucure or he delivery o energy, waer andsaniaion may also be easier wih higher concenraionso people. On he oher hand, concenraed economicaciviies and raffic can lead o environmenal problems

caused by air and waer polluion (OECD, 2012). Highgrowh raes also pu pressure on he abiliy o keep pacewih he required provision o waer and saniaionaciliies. Furhermore, one in every hree ciy dwellersworldwide abou one billion people currenly lives ina slum (UN-Habia, 2003; 2006). The oal number o

slum dwellers is expeced o grow, especially in rapidlygrowing ciies in developing counries. Problems wihsubsandard housing and inadequae waer, saniaionand wase managemen services could hereore becomemagnified (OECD, 2012).

Economic developmentsGDP growh under he Baseline Scenario is driven by:i) increasing he value added o producion hrough heincreased use o capial, labour and naural resources

(including land), ii) increasing he produciviy o heseprimary producion acors, and iii) reallocaing produc-ion acors o hose aciviies ha yield he highesvalue added. Beween 2010 and 2030, GDP growh willbe largely driven by he increased use o physical capial(such as buildings, machines and inrasrucure). In helonger erm, GDP growh will parially converge acrosseconomies and physical capial accumulaion and humancapial will conribue more equally o GDP growh.As a resul, global GDP will nearly quadruple beween2010 and 2050. The share o he developing counriesBrazil, Russia, Indonesia, China and Souh Arica is

projeced o grow o more han 40%, while he share odeveloped counries is projeced o decline rom 54% in2010 o around 30% by 2050. Arica is projeced oexperience high economic growh beween 2030 and2050, bu will remain he poores coninen (Figure 2.3).

Figure 2.1

1970 1990 2010 2030 2050

0

2

4

6

8

10

billion people

Source: UN DESA (2009; 2010)

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Sub-Saharan Africa

South Asia


Total population

1970 1990 2010 2030 2050

0

2

4

6

8

10

billion people

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Urban population



Developed countries

Population and urbanisation under the Baseline Scenario

Main socio-economic drivers population and urbanisation


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Figure 2.2

1970 1980 1990 2000 2010 2020 2030

0

1000

2000

3000

4000

5000

million people

Source: UN DESA (2010)

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City size

10 million or more

5 to 10 million

1 to 5 million

500,000 to 1 million

Fewer than 500,000

Global urban population, according to city size, under the Baseline Scenario

World urban population by city size, 19702025

Figure 2.3

Developing countries

Central and South

America

Middle East and

North Africa

Sub-Saharan Africa

South Asia

China region

Southeast Asia

Industrialised countries

North America

West and Central

Europe

Russian region and

Central Asia

Japan, Korea and

Oceania

GDP per region

Global GDP growth under the Baseline Scenario

1970 1990 2010 2030 2050

0

100

200

300

400

trillion USD2005

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History

Baseline Scenario

Range from literature

10% 90%

25% 75%

Range from literature

1970 1990 2010 2030 2050

0

100

200

300

400

trillion USD2005

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Source: World Bank (2009), OECD (2012) and literature range from Van Vuuren et al. (2012)

Global GDP trends under the Baseline Scenario


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2.4 Energy, land and climate in

relation to water

The rends skeched above will make demands on he

Earhs naural resources. In his secion, he impacs onenergy use, land and climae are oulined.

Energy productionEnergy use is essenially driven by economic aciviyand echnological developmens. Assuming no changein curren policies, he world energy demand by 2050is projeced o be abou 80% higher han i is oday,

wih ossil uels reaining a large marke share o 85%(OECD, 2012). This growing need or energy will lead oa growing waer demand or cooling in power saions(see Secion 2.5). Oher energy-use relaed impacs onhe waer sysem are higher flood peaks and lower basic

Figure 2.4Regional climate change, temperature and precipitation, in 2050,

under the Baseline Scenario

Change in annual temperature

Change in annual precipitation

Temperature change (C)

< 0.5

0.5 - 1.0

1.0 - 1.5

1.5 - 2.0

2.0 - 2.5

2.5 - 3.0

3.0 - 3.5

3.5 - 4.0

> 4.0

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l

Precipitation change (mm/day)

< -0.6

-0.6 - -0.4

-0.4 - -0.2

-0.2 - 0.0

0.0 - 0.2

0.2 - 0.4

0.4 - 0.6

0.6 - 0.8

0.8 - 1.0

> 1.0

Source: OECD (2012)

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l

Climate change under the Baseline Scenario


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river flows due o deoresaion caused by he use oradiional bio-energy, waer wihdrawal and polluionrelaed o he growing o irrigaed bio-energy cropsand he building o dams or hydropower generaion.Overall land-use change and irrigaion are included inhe Baseline Scenario; he effecs o river dams on waeravailabiliy and qualiy are no.

Land useThe area o agriculural land is projeced o expand in henex decade o mach he increase in ood demand rom agrowing populaion. Agriculural land is projeced o peakbeore 2030 and decline hereafer as populaion growhslows and yield improvemens coninue. Agriculural landarea will increase mos in he less developed counries,especially sub-Saharan Arica, where populaion andeconomic growh are projeced o be he larges.There is significan uncerainy abou he curren exeno and uure increase in irrigaed land and irrigaion

waer use. Under he Baseline Scenario, he area oirrigaed agriculural land is assumed o say consan upo 2050 or several reasons. For example, available landor irrigaion is scarce and where i is available i isunlikely o be irrigaed soon because o lack o

inrasrucure and limied public unds. Furhermore,here will be increasing compeiion wih oher waerdemands, and waer resources in highly irrigaed areasare declining. The assumpion ha he area o irrigaedagriculural land will remain consan means ha heBaseline Scenario may underesimae uure waer sressin some regions.

Climate changeAs a resul o increasing energy producion based onossil uels and increasing agriculural area expansion,he amospheric concenraions o greenhouse gases areprojeced o increase o almos 685 ppm CO2 equivalensby 2050. By he end o he 21s cenury, he global averageemperaure is likely o be 3 C o 6 C higher han pre-indusrial levels. This will coninue o aler precipiaionpaterns, mel glaciers and ice caps, cause sea-level riseand inensiy exreme weaher evens (OECD, 2012).Temperaure rises and changes in annual precipiaion

are geographically unequally disribued, hereby alsodifferenly affecing local agriculure and waer sysems(Figure 2.4).

Figure 2.5

Developed countries

2000

2050


2000

2050


2000

2050


2000

2050


2000

2050

South Asia

2000

2050

Sub-Saharan Africa

2000

2050

0 500 1000 1500 2000

km3

Source: OECD (2012)

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Irrigation

Households

Livestock

Manufacturing

Electricity

Blue-water demand under the Baseline Scenario

Blue water demand: 2000 and 2050 under the Baseline Scenario

Please note: Blue water here describes fresh water in aquifers, rivers and lakes, suitable for human use; for example, for irrigation, h uman consumption and

livestock, and in manufacturing and power generation.


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Figure 2.6

Developed countries

2000

2050


2000

2050


2000

2050


2000

2050


2000

2050

South Asia

2000

2050

Sub-Saharan Africa

2000

2050

0 1000 2000 3000

million people

Source: OECD (2012)

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No water stress

Low water stress

Medium water stress

Severe water stress

Number of people living under water stress under the Baseline Scenario

People experiencing water stress, under the Baseline Scenario

2.5 Water demand and water stress

This secion discusses waer demand and waer sressunder he Baseline Scenario. The Baseline Scenariosresuls or waer supply and saniaion, waer qualiyand flooding risks are described in Chapers 3, 4 and 5,respecively.

Water demand

Over he las cenury, waer demand has risen wice asas as populaion growh. In 2000, agriculure primarilyor irrigaion accouned or abou 70% o he oalglobal reshwaer demand. Elecriciy generaion primarily or cooling hermal (seam cycle-based)power generaion accouned or he second largesshare. Under he Baseline Scenario, global waer demandis projeced o increase by 55% beween 2000 and 2050,mainly caused by increased demand rom manuacuring(+400%), elecriciy producion (+140%) and domesicuse (+130%) (Figure 2.5). Sharp rises in waer demandare expeced in Souh Asia and China, as well as in oher

emerging economies. In he ace o hese growingdemands, compeiion beween urban claims and waeror irrigaion will inensiy.

Water stressIncreasing demand or waer will exacerbae waer sress(a waer exploiaion rae o more han 40%) in manyriver basins, in paricular in densely-populaed areas inrapidly-developing economies. More river basins areprojeced o come under severe waer sress by 2050under he Baseline Scenario, mainly as a resul o growingwaer demand. By 2050, 3.9 billion people over 40%o he worlds populaion are projeced o live under

severe waer sress (Figure 2.6). This holds or almoshe enire populaion o Souh Asia and he Middle Eas,and large pars o China and Norh Aricas populaion.In many regions o he world, groundwaer is beingexploied aser han i can be replenished. The rae ogroundwaer depleion more han doubled beween1960 and 2000, reaching over 280 km3 a year in 2000.The consequences or daily lie are uncerain, and dependgrealy on he adequacy o waer managemen sraegiespu in place.


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Water supply and sanitationTHREE

3.1 Main messages

The number o people wih access o a sae waersupply is projeced o increase, while developmenswih respec o basic saniaion will lag behind,especially in sub-Saharan Arica.

Invesmens in sae waer supply and improvedsaniaion show a posiive cos-benefi raio in ermso coss, healh impacs and valuaion o he healhimpacs.

The Millennium Developmen Goal relaing o an

improved source should be advanced owards asae source.

3.2 Introduction

In 2011, almos 800 million people did no have accesso an improved drinking waer source, while around2.5 billion people lacked access o an improved saniaionaciliy (WHO/UNICEF, 2013). Around 70% o all peoplewihou improved saniaion live in Asia, while progresshas been slowes over he las decade in sub-SaharanArica. Alhough almos 1.9 billion people have gained

access o an improved saniaion aciliy since 1990, inrelaive erms he siuaion has worsened in Souh Asiaand sub-Saharan Arica (Figure 3.1). O hese 1.9 billionpeople, 1.1 billion people gained access in urban areas,while he oal urban populaion grew during he sameperiod by 1.3 billion. An imporan quesion hereore iswheher uure increases in connecion raes will be ableo keep up wih urher rising urbanisaion raes.

Sae drinking waer and basic saniaion are imporan ohuman healh. Furhermore, improvemens in saedrinking waer and basic saniaion can have significan

economic benefis. These benefis relae o an improvedhealh saus (in relaion o morbidiy and moraliy),ime saved in waer collecion and increased poenial orsmall enerprises.

In 2004, unsae waer supply and saniaion (WSS) andhe associaed exposure o pahogenic micro-organismswere responsible or around 1.8 million deahs and 6.3%o worldwide disabiliy-adjused lie years (DALYs) (WHO,2013). The DALY is a measure o disease burden ha, aswell as moraliy, also accouns or morbidiy anddisabiliy. The vas majoriy (around 80%) o hese deahswere observed in Arica and Souheas Asia. More han80% o all waer-supply and saniaion-relaed deahswere in children under 5 years o age. Children have aneven larger share (85%) o oal DALYs relaed o waer

supply and saniaion (Prss-sn e al., 2008).Unsae waer supply and saniaion is an imporandeerminan o diarrhoeal diseases. Approximaely 88%o diarrhoeal deahs globally are caused by unsae waer,poor saniaion or poor hygiene, and 99% o hese are indeveloping counries (WHO, 2009a). Unsae waer supplyand saniaion is hereore he ourh larges cause odisease burden in low-income counries, afer childunderweigh, high blood pressure and unsae sex. I isimporan o noe ha he risk acors canno beconsidered independenly, as he effecs o unsaedrinking waer and saniaion can be aggravaed by childunderweigh. In addiion, climae change, hrough

emperaure increases ha affec waer qualiy, also hasa negaive effec on diarrhoeal diseases. I is no only inhealh erms ha he significance o waer supply andsaniaion is high, bu i also has a subsanial impac infinancial erms. In Arica alone, economic losses due o alack o access o sae drinking waer or human con-sumpion and saniaion is esimaed o oal abou 5%o GDP per year (UN-WWAP, 2009).

Access o clean drinking waer and saniaion haseconomic, environmenal and social benefis. Benefi-o-cos raios have been repored o be as high as 7 o 1 in

developing counries (OECD, 2011). Three quarers ohese benefis sem rom ime gains, due o less imebeing spen having o walk long disances o collec waeror o queue a he waer source. The oher benefis arelargely linked o a reducion in diarrhoea.


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233 Waer supply and saniaion |

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Oher non-healh benefis mus hereore be aken inoconsideraion when adding up he ull benefis oimproved access o waer and saniaion. These benefismean ha here is more ime available or educaion, anda more producive labour orce.Healh expers have debaed wheher waer quaniy orwaer qualiy maters mos in erms o driving healhbenefis. Cairncross and Valdmanis (2006) esimae hamos o he benefis rom a waer supply are atribuableo improved convenience o access o waer in erms oquaniy. Oher expers argue ha waer qualiy is acriical deerminan driving healh benefis. Waddingon

(2009) poins ou ha while waer supply inervenionsappear ineffecive wih a negligible or insignificanimpac on diarrhoea morbidiy on average waer qualiyinervenions can reduce he incidence o diarrhoea inchildren by abou 40%. Prss e al. (2002) sae ha poin

o use reamen soluions (such as boiling) cansignificanly improve he impac o waer supplyinervenions, wih an esimaed 45% reducion indiarrhoea raes. Such analyss argue ha reamen a hepoin o use is more effecive han reamen a he poino source.Large benefis were reaped in many developed counriesin he lae 19h and early 20h cenuries when basic waerand saniaion inrasrucure was exended o muchlarger pars o he populaion. For insance, heinroducion o waer chlorinaion and filraion in 13major US ciies during he early 20h cenury led o

significan reducions in moraliy, wih a calculaedbenefi o cos raio o sociey o 23 o 1 and a saving oabou USD 500 per person in 2003 (OECD, 2011). Thebenefis o wasewaer reamen are no obvious o hepublic and are more difficul o assess in moneary erms.

Figure 3.1

I II III I II III I II III I II III I II III I II III I II III1 2 3 4 5 6 7

0

500

1000

1500

2000

2500

million people

Source: WHO/UNICEF (2013)

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Type of sanitation:

Improved

Unimproved

Population grouped by type of sanitation

1 Developed countries2 Latin America and the Caribbean3 East Asia and Pacific

4 Russian region and Central Asia5 Middle East and North Africa6 South Asia

7 Sub-Saharan Africa

I: 1990 II: 2000 III: 2010

Population grouped per type of sanitation, 1990, 2000 and 2010

Table 3.1Deahs and burden of disease atribuable o waer, saniaion and hygiene in 2004 (WHO, 2013)

Region Atribuable deahs (housands) Atribuable DALYs (housands)

Toal Children Toal Children

Arica , ,

Americas , ,

Souheas Asia , ,

Europe ,

Easern Medierranean , ,

Wesern Pacific , ,

Toal , , , ,


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However, anecdoal evidence can be derived rom casesudies. For insance, he healh benefis o qualiy

improvemens in recreaional waers in souh-wesScoland have been calculaed a GBP 1.3 million per year(Hanley e al., 2003).

3.3 Modelling water supply and

sanitation and associated health

impacts

Waer supply and saniaion can be caegorised accordingo hree levels o service: no coverage, improved services(such as public sandpipes or boreholes) and household

connecions. Each o hese levels has a paricular riskpoenial or incidence o diarrhoea (Cairncross andValdmanis, 2006). The proporion o he populaion halacks access o sae drinking waer and basic saniaionwas modelled or hese differen service levels (noe: hehird service level was only modelled or drinking waer).The service levels were modelled by applying linearregressions wih GDP per capia, urbanisaion rae andpopulaion densiy. Service level daa were aken romhe Join Monioring Programme (JMP) or Waer Supplyand Saniaion ( WHO/UNICEF, 2012). Developmens inwaer supply were assumed o be implemened ahead o

saniaion and were modelled separaely or urban andrural populaions. I is imporan o emphasise he saeyo he waer provided, as household connecions may nonecessarily provide saer waer han improved services.I is also imporan o noe ha he JMP measures access

o specific waer supply and saniaion echnologies,raher han he acual qualiy o service o which

people have access. The projecions migh hereoreoveresimae waer supply and saniaion coverage raes.The coss o he projeced connecion raes are based onHuton and Haller (2004), who esimaed he annual coso various levels o connecion. Their annual cosassumpions are based on invesmen and recurrencoss, using values rom he lieraure. For example, heannual cos o in-house piped waer is USD 10 o 15 perperson, while oher improved waer supply connecionscos USD 1 o 4 per person. I is imporan o noe ha hecoss in his simulaion are approximae, since hecaegories and regions do no ully mach hose appliedby Huton and Haller.

The waer-supply- and saniaion-relaed healh impacswere modelled using risk acor-atribuable moraliy,based on a muli-sae approach, disinguishingexposure, disease and deah (Cairncross and Valdmanis,2006; WHO, 2002). Moraliy raes due o specificdiseases (e.g. diarrhoea) were obained by muliplying heincidence rae wih he case aaliy rae. The impacs owaer supply and saniaion were only calculaed orchildren under he age o five. Given he differenconnecion levels o waer supply and saniaion aciliies,relaive risks were used o calculae incidence raes.These relaive risks were based on he esimaes o he

realisic scenario used in he Disease Conrol PrioriiesProjec (DCPP; Cairncross and Valdmanis, 2006). Theincidence rae was modified by he exen o which a childis underweigh (caegorised as mild, moderae or severeunderweigh; see Edejer e al., 2005) and climae change

Tex box 3.1 Overcoming healh concerns surrounding waer reuse and recycling

Reused waer (eiher reclaimed waer or grey waer, such as domesic wasewaer used or laundry, dishwashingor bahing) is increasingly seen as a susainable source or some waer uses, in paricular irrigaion, groundwaerrecharge and possibly non-poable domesic uses. I could be an opion or addressing he increasing mismachbeween rising demand and available waer resources in boh OECD and developing counries. Reused waer canbe supplied rom eiher cenralised or decenralised disribuion sysems.Markes or waer reuse are booming. In addiion, emerging economies and rural areas are gaining experiencewih disribued waer inrasrucure sysems or waer supply and saniaion services, alhough his is less hecase in urban areas in OECD counries. Ausralia, Israel, Spain and some saes in he Unied Saes are pioneer-ing hese new echnologies, spurred on by serious consrains o waer resources. However, healh-relaedissues are a major driver, or consrain, in he developmen o such sysems. Firs o all, hese sysems can gen-erae public healh risks (such as possible waer conaminaion during domesic use, or he salinisaion o irri-

gaed soils). Secondly, he payback period o he addiional invesmen cos or such sysems (due o addiionalequipmen, or in-house dual plumbing, or insance) depends on he sandards se by he regulaory agencies(environmen and/or healh auhoriies) or reused waer. These sandards govern wha waer can be harvesed,qualiy sandards or reused waer or specific applicaions, building sandards, agriculural sandards, and soon. The Naional Waer Qualiy Managemen Sraegy in Ausralia, or example, addresses healh risks by in-cluding qualiy guidelines and monioring or he sae use o recycled waer, and includes an easy-o-use Deci-sion Suppor Tool o help users creae a draf managemen plan or heir waer recycling scheme.For more deailed inormaion see OECD (2009).


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Figure 3.2

Developed countries





South Asia

Sub-Saharan Africa

0 100 200 300 400 500

million people


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1990

2010

2030

2050

Rural population without an improved drinking water supply

Population without improved water supply in rural areas, 1990, 2010, 2030 and 2050

Figure 3.3

Developed countries





South Asia

Sub-Saharan Africa

0 20 40 60 80

million people


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1990

2010

2030

2050

Urban population without an improved drinking water supply

Population without improved water supply in urban areas, 1990, 2010, 2030 and 2050

(McMichael, 2004). The case aaliy raes were modifiedby underweigh levels and he use o oral rehydraionherapy (ORT). Underweigh levels were derived romaverage ood consumpion levels.The caegory improved waer supply and saniaionencompasses a broad range o possible ypes oconnecion, each o which is assumed o lead o he samehealh risk poenial. The analysis considers only wo

classes o urbanisaion urban and rural. However, hismay no reflec all siuaions wihin urban areas (whichcan include slums and more affluen areas). Whileincreasing waer and saniaion connecions may beeasier o achieve in urban areas, i is no always he case

ha increased urbanisaion leads o more connecions.I may insead lead o greaer healh risks, such as lessavourable living condiions. Empirical daa on hecombinaion o waer supply and saniaion caegoriesare lacking, alhough he healh risks are specificallyrelaed o combinaions o he wo. The assumpion washereore made ha here is no dependency beween hewo, which may affec he esimaion o healh risks.


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3.4 Trends and projectionThe Millennium Developmen Goals (MDGs) se argesor human developmen, including a arge or waersupply and saniaion (UN, 2000). The arge is o halve,by 2015, he proporion o people wihou susainableaccess o sae drinking waer and basic saniaion(Targe 7.C). The reerence year or his arge is 1990.Under he Baseline Scenario, he world as a whole wouldmee he MDG drinking waer arge by 2015, alhoughhis will mainly be due o he rapid progress made in largeemerging economies such as China and India. In Eas Asiain paricular, remarkable progress has been made in

waer supply coverage raes in recen decades, and wihconinuing economic growh universal coverage in hisregion will almos be achieved by 2030 (Figures 3.2 and3.3). Oher regions, such as sub-Saharan Arica, areunlikely o mee he waer supply arge. The number ociy dwellers wihou access o an improved waer sourceacually increased beween 1990 and 2008, asurbanisaion oupaced progress in access. By 2050, socio-economic progress in urban areas is projeced in allregions. In rural areas, and especially in sub-SaharanArica, he number o people lacking an improved waersupply will increase up o 2030 and only slighly decrease

aferwards. Under he Baseline Scenario, access o animproved waer supply is expeced o be universal inmore developed counries beore 2050.

Progress is slower wih regard o access o saniaion.Under he Baseline Scenario, he MDG saniaion argewill no be me, while by 2030 more han wo billionpeople will sill lack basic saniaion aciliies (Figures 3.4and 3.5). This number will only drop in he longer erm, o1.5 billion by 2050. In 2030, he majoriy o hose wihouimproved saniaion will live in developing counries, andhis proporion will coninue o grow owards 2050.Today, he vas majoriy o people wihou access o a

waer supply and saniaion live in rural areas. However,owards 2050 he number o people in rural areas wihouaccess o saniaion will drop significanly and becomecomparable o numbers in urban areas.

3.5 Impacts on human health

Wih greaer access o an improved waer supply andsaniaion aciliies, he Baseline Scenario projecs hahe coming decades will see a subsanial reducionin child moraliy rom diarrhoea. A he beginning o

his cenury, almos wo million annual deahs, moslychildren, could be atribued o a lack o basic waersupply and saniaion aciliies. Under he BaselineScenario, his number is projeced o be around 1 millionby 2030 and abou 0.5 million by 2050 (Figure 3.6). As a

resul o he coverage rae projecions, mos o hesedeahs will occur in sub-Saharan Arica, alhough henumber will also decline seadily in his region.These projecions implicily assume ha increasingurbanisaion will make i easier and cheaper o connecresidens o waer supplies and saniaion aciliies, hagreaer economic growh will increase he basic sandardo living (including access o medical reamen), and hahe number o people mos suscepible o unsae waerand saniaion (i.e. children under he age o five) willdecrease due o he coninuing ageing o he populaionin mos counries, including developing counries.Despie hese assumpions, i is imporan o noe ha

greaer urbanisaion can in some cases magniy waerchallenges such as he managemen o wase and waerin slums (see Chaper 4) wih serious consequences orhuman healh.

3.6 Policy options

To assess he impacs o improved access o sae drinkingwaer and improved saniaion, an Acceleraed AccessScenario was consruced. This policy simulaion wasused o esimae he expeced addiional annual cos and

healh benefis o achieving universal access o improvedwaer supply and saniaion by 2050. Compared wih heBaseline Scenario, his simulaion assumes: i) halving,by 2030, he populaion wihou access o an improvedwaer source and basic saniaion compared wih hebase year 2005, and hen ii) moving o universal access by2050. The resuls are presened in Table 3.2.Compared wih he Baseline Scenario, almos 100 millionaddiional people will have access o an improved sourceo waer by 2030 under he Acceleraed Access Scenario,and around 470 million more will have access o sani-aion aciliies. By 2050, universal access will mean haan addiional 242 million people will have access o an

improved waer source, and an addiional 1.36 billionpeople will have access o basic saniaion aciliies.In erms o healh impacs over he nex 40 years, hehighes number o avoided deahs under his policy willbe in sub-Saharan Arica, where every year around 70,000deahs relaed o unsae drinking waer and saniaionwill be avoided. I is imporan o noe ha while accesso improved waer sources will increase subsanially,here will no be a commensurae reducion in moraliy.One reason is ha an improved waer source sill involvesrelaively high healh risks compared wih a householdconnecion. Also, a connecion does no necessarily

ensure access o sae waer.The policy simulaion indicaes ha an average oUSD 1.9 billion globally would need o be invesed eachyear beween 2010 and 2030 o achieve he 2030 arge,and USD 7.6 billion would be needed annually beween2031 and 2050 o achieve he 2050 arge.


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Figure 3.4

Developed countries





South Asia

Sub-Saharan Africa

0 200 400 600 800 1000

million people


pbl.nl

1990

2010

2030

2050

Rural population without improved sanitation

Population without improved sanitation in urban areas, 1990, 2010, 2030 and 2050

Figure 3.5

Developed countries





South Asia

Sub-Saharan Africa

0 100 200 300 400

million people


pbl.nl

1990

2010

2030

2050

Urban population without improved sanitation

Population without improved sanitation in rural areas, 1990, 2010, 2030 and 2050


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Figure 3.6

2000 2010 2020 2030 2040 2050

0.0

0.4

0.8

1.2

1.6

2.0

Child deaths (millions)


pbl.nl

Developed countries





South Asia

Sub-Saharan Africa

Annual child deaths due to the lack of basic water supply and sanitation

Annual child deaths due to lack of basic water supply and sanitation, 20002050

Table 3.2Impacs of acceleraed access o waer supply and saniaion, 2030 and 2050, compared wih he

Baseline Scenario

Addiional waer

Supply

Addiional

saniaion

Addiional cos Avoided deahs Addiional value

of saisical life

(VSL)

2030 Thousands Thousands Million USD Thousands % o GDP

Developed counries .

Lain America & he

Caribbean

, .

Eas Asia & Pacific , .

Russian region &

Cenral Asia

.

Middle Eas & Norh Africa , .

Souh Asia , , .

Sub-Saharan Africa , , , .

2050Developed counries .

Lain America &

he Caribbean

, .

Eas Asia & Pacific , , , .

Russian region &

Cenral Asia

, .

Middle Eas & Norh Africa , .

Souh Asia , , , .

Sub-Saharan Africa , , , .


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314 Waer qualiy: nuriens in surace waer |

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reamen, and many ciies are now conneced o eriaryreamen plans wih a high nurien removal efficiency.The nex generaion o wasewaer reamen plans willremove more nirogen and phosphorus rom he effluen,make he reuse o phosphorus possible and have muchlower energy coss. The impacs o differen ypes osaniaion and wasewaer reamen on waer qualiyare presened in Table 4.1.Improving public healh and reducing negaive impacson he environmen are a major concern in many

counries. Many urban areas in developing counries dono have a public sewage sysem, and here are ofen nowasewaer reamen sysems. Improved saniaion wihsepic anks is an alernaive when sewage sysems areno available, and orm an improvemen in erms opublic healh, alhough sysems wih sepic anks maycause groundwaer or surace waer polluion when heoverflow ends up in soil or groundwaer, or unreaedsludge rom sepic anks is dumped on land or in suracewaer.

The effec o GDP growh and urbanisaion is wo-sided.A growh in GDP allows or invesmen in improved

saniaion and he consrucion o sewage sysems inurban areas, alhough he consrucion o wasewaerreamen plans ofen lags behind he consrucion osewage sysems so ha wasewaer is discharged direclyo surace waer. On he oher hand, consumpionpaterns also change as incomes grow. Generally-speaking, here is a shif owards more proeins rommea and milk in human dies, causing increased nirogenexcreion, and access o drinking waer means ha morehouseholds own a dishwasher and laundry machine,which ofen use phosphorus-based deergens.In he ollowing secions, we presen a global counry-

scale modelling approach o show pas and uurechanges in he discharge o nuriens in wasewaer osurace waer. These changes are illusraed usingexamples rom differen ciies. Saniaion opions oimprove waer qualiy are presened and finally he

effecs o high nurien loads in surace waer arediscussed. The discussion is limied o urban wasewaer.Nurien loading caused by agriculure and oherpolluans such as pahogens, heavy meals and plasicsare no discussed.

4.3 Modelling emissions from urban

areas to surface water

Nurien emissions rom households and indusries inurban areas were calculaed using a global counry-scalemodel (Van Drech e al., 2009; More e al., 2013). Themodel also describes nurien emissions rom urban live-sock and racion animals where relevan. Inpu daa orhe model include urban populaion, connecion o sew-age sysems and he presence and ype o wasewaerreamen (Figure 4.1). Human excreion o nuriensdepends on ood proein inake. The proein inake percapia ranges by a acor o hree beween he pooresand he wealhies counries. Proeins are assumed ohave a nirogen conen o 16% and a phosphorus conen

o 1.6%. The model also accouns or phosphorus emis-sions rom he use o phosphorus-based deergens inlaundry machines and dishwashers, and he exen owhich phosphorus-ree deergens are used (e.g. due oregulaions). The removal o nirogen and phosphorus inprimary reamen plans is 10%; in secondary reamen45% or phosphorus and 35% or nirogen; and in eriaryreamen plans 90% and 80% respecively.Emissions o surace waer are divided ino hree sources(Figure 4.1): households in urban and rural areas ha are

conneced o a sewage sysem where wasewaer is

discharged unreaed or is reaed in a wasewaerreamen plan;

households in urban areas ha are no conneced oa sewage sysem, and direc discharge o wasewaerhrough open sewers is assumed;

Table 4.1The impac of he mos imporan phases in saniaion and wasewaer reamen on waer qualiy

Saniaion Nuriens / organic polluion Waer qualiy effecs

No access o improved saniaion Use in agriculure as erilizer Minor or local effecs

Access o improved saniaion, no sewage

sysem

Sludge dumped in land or waer Negaive effecs

Access o improved saniaion, sewage

sysem, no reamen

Nuriens discharged direcly o surace waer Major negaive effecs


sysem and wasewaer reamen

Wih more advanced reamen more nuriens areremoved rom he effluen; he removed nurien sare sored in sewage sludge

Wih increase owasewaer reamenewer effecs


sysem and advanced reamen

Nearly all nuriens removed rom effluen, reuse ophosphorus is possible

Hardly any effecs


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households in rural areas ha are no conneced o asewage sysem, and he reuse o wase in agriculureor collecion o wase in sepic anks wihou a direcconnecion o surace waer is assumed.

A cenury ago, he dominan pahway or nuriens wasreuse in agriculure; nowadays he dominan pahwayends in surace waer. In some developed counries, mos

nuriens are removed rom he wasewaer. Nirogen isremoved by denirificaion and phosphorus is deposiedin reamen sludge.The spaial resoluion o he model is one degree by onedegree or he populaion densiy and urbanisaion andcounry-based inormaion on sewage sysems andwasewaer reamen. Resuls were aggregaed o heriver basin or counry level.

4.4 Trends and projection

The number o households conneced o a sewagesysem will increase in all regions (Figure 4.2; Table4.2). In absolue numbers, he larges increase willbe in Eas Asia, Souh Asia and sub-Saharan Arica.The smalles increase in sewage connecion will be in

he Russian region and Cenral Asia and in developedcounries. Mos wasewaer in developed counries, by2050, will be reaed using eriary reamen. In oherregions, he sewage effluen will be reaed using aprimary or secondary reamen plan, or dischargedwihou reamen. In sub-Saharan Arica and SouhAsia, populaion growh will be higher han he growhin sewage sysems. Mos ciies in sub-Saharan Arica

(excep in Souh Arica) do no have a sewage sysem orhave a small sewage sysem which no longer uncions(Miller and Parker, 2013; Tex box 4.1). Improvemens ohe sewage sysem will ake place in he more well-offdisrics o ciies, bu very ew wasewaer reamenplans will be buil. In Lain America, he Russian region,Norh Arica and he Middle Eas, improvemens in hesewage sysem and wasewaer reamen will be enougho compensae or populaion growh. In China (EasAsia region), improvemens in wasewaer reamen willexceed populaion growh.

Emissions o nirogen and phosphorus rom householdso surace waer will increase in mos regions (Table 4.2;Figures 4.3 and 4.4). In developed counries, nurienemissions decreased beween 1990 and 2010 and willconinue o decrease up o 2050. Wasewaer reamen

Figure 4.1Different pathways of household emissions of nitrogen and phosphorus

Humans Food

Excreta

Sewer

Treatment

Removed

nutrients

No sewer

Agriculture Surface water Other

No treatment

Retail and

household waste

Non-urine/-faeces

(sweat/hair)

Sewer losses

Main nutrient fluxes

System losses

Detergent P

pbl.nl

Source: More et al. (2013)

Different pathways of human emissions of nitrogen and phosphorus from households (More et al., 2013)


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plans are being upgraded o eriary reamen sysemswih 80% nurien removal or wih 95% or more nurienremoval using new echnologies in wasewaer rea-men. Inernaional agreemens are imporan orcounries o inves in wasewaer reamen o improvewaer qualiy downsream. In he European Union, heguideline is ha all ciies have a eriary reamen planor heir wasewaer (EEC, 1991).An increase in emissions is projeced or oher coninens.Emissions in he Russian region and Cenral Asia show asligh increase. Emissions in Lain America and he Middle

Eas and Norh Arica region will increase by 15% o 50%.The increase in emissions will be less han expeced rompopulaion growh as wasewaer reamen improve-mens will be considerable. An imporan driver in

improving wasewaer reamen will be reuse o heeffluen in agriculure (Tex box 4.2).A subsanial increase in emissions is expeced in Aricaand Souh Asia, mainly due o populaion growh andurbanisaion and he consrucion o sewage sysemswihou appropriae wasewaer reamen. Alhoughprogress will ake place in he connecion o householdso sewage sysems, populaion growh will be higher.Toal global emissions o nirogen will increase rom9.5 o 13.5 million onnes and phosphorus emissions rom1.3 o 2 million onnes. Figure 4.4 shows he spaial disri-

buion o nirogen and phosphorus emissions in 2050 andhe differences beween 2050 and 2010. This map showshe conras beween developed counries wih areducion in emissions and he counries in which herewill be a major increase in Souh and Eas Asia.

Tex box 4.1 The ciy of Accra (Ghana)

Accra is a rapidly growing coasal ciy and he capial o Ghana. The number o inhabians in he AccraMeropolian Area is currenly esimaed o be around our million. There are large differences in incomebeween differen areas o he ciy, bu he majoriy o inhabians live in non- or poorly-planned residenialareas, some o which are slums. The ciy is sprawling and his urher complicaes he provision o waer serviceso is inhabians. This is characerisic o he siuaion in many ciies in sub-Saharan Arica. In Ghana, only 13%o he oal populaion has access o improved saniaion, bu nearly 60% has shared, unimproved saniaion,which means ha mos people do no have a oile.Only a minor par o he ciy (5% o 10%) is conneced o a cenral sewerage sysem, which discharges o areamen plan ha is mosly ou o operaion. The aecal sludge rom public oiles or privae larines and sepicanks is colleced in privae anker rucks. These rucks dump abou 100 anks o aecal sludge on he beach nearhe ciy cenre each day. This is he larges source o polluion and causes major marine polluion. Only 20% o he

urban populaion has access o improved saniaion, bu many people have a shared saniaion sysem.The populaion will cerainly increase, o beween 8 and 16 million inhabians by 2030, wih a correspondingincrease in wasewaer and sludge. Managemen o he waer, wase and wasewaer sysem is mosly ad-hoc,wihou long-erm planning. Expansion o he ciy ino he upper cachmen areas will also resul in increasedsorm waer flows and flooding by pollued waer in he lower pars o he cachmen area, wih negaiveconsequences or healh. (Miller and Parker, 2013).

Table 4.2The relaive change in populaion size, urban populaion, he populaion conneced o a sewage sysem and

nirogen and phosphorus emissions o surface waer beween 2010 and 2050

Toal

populaion, in %

Urban

populaion, in %

Populaion

conneced o

sewage sysem,

in %

Nirogen

emissions, in %

Phosphorus

emissions, in %

Developed counries + + + - -

Lain America & he Caribbean + + + + +

Eas Asia and Pacific + + + + +

Russian region and Cenral Asia ~ + + - +

Middle Eas and Norh Arica + + + + +

Souh Asia + + + + +

Sub-Saharan Arica + + + + +


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Figure 4.2

I II III I II III I II III I II III I II III I II III I II III1 2 3 4 5 6 7

0

500

1000

1500

2000

2500

million people

Source: PBL

pbl.nl

Type of treatment:

Tertiary treatment

Secundary treatment

Primary treatment

Connected, no treatment

Not connected

Population grouped according to type of waste-water treatment

1 Developed countries2 Latin America and the Caribbean3 East Asia and Pacific

4 Russian region and Central Asia5 Middle East and North Africa6 South Asia7 Sub-Saharan Africa

I: 1970 II: 2010 III: 2050

Total population grouped by type of wastewater treatment showing the absolute growth and the improvement in wastewater

treatment between 1970 and 2050

Figure 4.3

1970 1990 2010 2030 2050

0

1

2

3

4

5

million tonnes N/year

Source: OECD (2012)

pbl

.nl


South Asia

Sub-Saharan Africa

Developed countries

Nitrogen emissions

1970 1990 2010 2030 2050

0

200

400

600

800

thousand tonnes P/year

pbl

.nl

Phosphorus emissions

Household nutrient emissions to surface water




Nitrogen and phosphorus emissions to surface water from households


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4.5 Negative effects of eutrophication

on cities and coastal areas

Increasing nurien loads caused by human aciviies leado europhicaion, as well as changing raios beween

nirogen, phosphorus and silica (he soichiomery;Garnier e al., 2010). The mos imporan group o algaein oceans wih respec o phoosynhesis are diaoms,which need silica o orm heir cell walls. Many humanaciviies on he land resul in a changed soichiomery,

or example he consrucion o dams resuls in hereenion o silica, and unreaed wasewaer flowscause elevaed nirogen and phosphorus levels. Thus,N:Si and P:Si raios have increased in many pars o heworld, ofen resuling in limied diaom growh andhe simulaion o oher, ofen harmul, phyoplankon

such as dinoflagellaes. This can lead o a prolieraiono Harmul Algal Blooms (HABs) (Heisler e al., 2008).HABs cause loss o naural resources, desrucion oaquaculure producion and human sickness and deah,or insance i shellfish are consumed ha conain oxins

Figure 4.4Spatial distribution of phosphorus emissions in 2050

Phosphorus emissions by households in 2050

Differences in phosphorus emissions between 2050 and 2010

Tonnes P/ (2*2 degrees)

> 5,000

1,000 - 5,000

500 - 1,000

100 - 500

50 - 100

1 - 50

0 - 1

Source: PBL

Tonnes P / (2*2 degrees)

Decrease more than 100

Decrease less than 100

Stable

Increase less than 1,000

Increase more than 1,000

pbl.n

l

pbl.n

l

Spatial distribution of phosphorus emissions in 2050 and the difference in emissions between 2010 and 2050


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produced by hese algae. Several cases o human illnessand deah have been repored in he Unied Saesand Mexico (Lewius e al., 2012). Well-known healh

problems include paralyic, amnesic, neurooxic anddiarrheic shellfish poisoning. Cyanooxic poisoning maycause skin or respiraory irriaion, umour promoionand liver cancer.Several algal blooms have been repored in recen yearswih negaive effecs on ecosysem ser vices. For exam-ple, large algal blooms o dinoflagellaes have been seensince 2000 in he Changjiang (Yangze River) Esuary andhe adjacen area o he Eas China Sea (Li e al., 2009).A oal o 440 million people live in he Yangzecachmen area, which also includes 4 o he 10 mospopulaed ciies in China, bu he hydrology has alsochanged wih he consrucion o he Three Gorges Dam.

The Yangze River has high nurien loads, bu nirogenconcenraions are paricularly elevaed relaive ophosphorus. The molar raio N:P is normally 10:1, buin he Changjiang Esuary i is 40:1. Combined wih hecoasal sea currens, he mix o nuriens has resuled inhe massive growh o harmul algae. Beore 2000,diaoms bloomed requenly during spring bu afer 2000algae blooms wih dinoflagellaes have becomedominan. The area o algal blooms increased rom 1,000km2 in 2000 o 15,000 km2 in 2005, and were associaedwih massive fish kills on reaching he coasal aquaculureareas.

Several recen examples o massive die-offs o fish andaquaculure have also been seen in oher coasal seas inSouheas Asia. In he Philippines, fishery and aqua-culure are imporan or ood producion. In Manila Bay,or example, fish cages cover 40 km2 and even larger

areas in oher bays. Several fish-kill evens have occurreddue o hypoxia rom algal blooms (David e al., 2009).Algal blooms have been repored o cover over 500

kilomeres o coasline in he Philippines. In Malaysia, hefirs Harmul Algae Blooms were repored in 2005 (Anone al., 2008). These blooms caused red discoloraion ocoasal waers, coinciding wih exensive moraliies ocaged fish in local aquaculure arms. There are alsoincidens o Harmul Algae Blooms and fish-kills inIndonesia and Korea, or example in Jakara Bay.Figure 4.5 shows he locaions o observed Harmul AlgaeBlooms in 1970 and 2000. The change over his 30-yearperiod illusraes he increasing prolieraion o paralyicshellfish poisoning. In reshwaer lakes oo, high nurienlevels are a risk or drinking waer in ciies. Tai Hu inChina, one o he larges reshwaer lakes, has suffered

rom high concenraions o cyanobaceria or severaldecades. The combined effec o nurien enrichmen andindusrial polluion pushed Tai Hu o a rapid and massivedie-off o cyanobaceria (Zhang e al., 2010), and drinkingwaer exracion rom he lake or Wuxi ciy wih is womillion inhabians had o be sopped.In addiion o oxic algae, a special ype o Harmul AlgaeBlooms is high-biomass o green macroalgae, which growrapidly in nurien-rich waers. The vas accumulaionsand rapid growh o unatached green macroalgae arecalled green ides. In he Yellow Sea, large-scale greenides broke ou coninuously beween 2007 and 2013, and

in 2008 in paricular he algal bloom covered an area o13,00030,000 km2 near Qingdao (Zhang e al., 2013).Alhough 700,000 onnes o algae were removed a aoal cos o over USD 100 million o mainain algae-ree

Tex box 4.2 Israel/Tel Aviv

Tel Aviv ciy was esablished in 1909 and since hen has developed ino a meropolian region o around2.5 million inhabians. The ciy has a separae sewerage sysem, which is operaed by a publicly-ownedcompany. The sewerage sysem, wih nearly 6,000 kilomeres o pipeline, ranspors abou 114,000 m3 owasewaer a day o he regional sewage reamen plan. The wasewaer is subjeced o secondary reamenwih nurien removal (single-sage simulaneous nirificaion-denirificaion) and he effluen is urher reaedin a Soil Aquier Treamen (SAT) sysem. The SAT sysem consiss o large infilraion basins and a ring orecovery wells a considerable disance rom he infilraion basins or a residence ime o up o 100 days. As aresul, he qualiy o he recovered waer is good enough or unresriced irrigaion and conveyed owards henorhern pars o he Negev deser.Several uure changes are expeced o affec he ciys waer sysem. Due o urher urbanisaion and increasingland prices, he infilraion area will be reduced. One opion will be o replace he SAT sysem wih membrane

sysems (e.g. ulra-filraion wih reverse osmosis) or o combine membrane sysems wih shor reenion imeSAT sysems. The goal is hen o use less expensive land. The membrane sysems have he addiionaladvanage ha hey can remove micro-polluans rom he reclaimed waer, such as endocrine disrupors,anibioics and oher pharmaceuical micro-polluans. This will urher proec public healh and enable heconinued expor o rui and vegeables o high-value markes in Europe and oher regions. A disadvanage ohe membrane sysems is heir relaively high energy cos, alhough he sysems are becoming more energyefficien each year.


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waer or he Olympic sailing games, he beach oQingdao is sill unusable or ourism.The negaive effecs o a disurbed nurien load haveincreased in he las 20 o 40 years and nurien loads willurher increase in he nex 40 years. Negaive effecs onfishery, aquaculure and ourism are expeced o increasein he coming period as he nurien load coninues oincrease. This can have negaive effecs on hesusainable developmen o ciies and coasal areas andon he ecosysem services o coasal seas and reshwaerlakes and rivers.

4.6 Policy options

Various opions are available or reducing polluion romwasewaer. In developing counries wih a low degreeo connecion o sewage sysems and no wasewaerreamen, small-scale soluions wih sludge reamenare an ineresing opion. In developed counries,advanced wasewaer reamen wih more nurienremoval and a lower energy consumpion or small-scaleadvanced reamen sysems are opions or improvingwaer qualiy.

Figure 4.5Increase n Para yt c e s Po son ng (P P) rom Harm u A gae B ooms

Source: Glibert et al. (2005)

Increase in Paralytic Shellfish Poisoning (PSP) from Harmful Algae Blooms (Glibert et al., 2005)


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Developing countries link local sanitation withfaecal sludge managementIn slum areas, small-scale, local opions are ofen hebes way o improve saniaion and waer reamen.The coverage o sewerage sysems in ciies is exremelylow; many Arican capials have coverage raes o lesshan 10%. The cos o expanding sewerage sysems is inmany cases prohibiive. New echnologies and incenivesor local reuse may provide an alernaive o cenralisedopions. There should be a paricular ocus on dealingwih aecal sludge rom sepic anks, pi larines andpublic oiles, since his is by ar he mos common ormo wase waer in he developing world.

Shared oiles wih wase collecion and reamen are asignifican improvemen in he slums o many ciies.One example o an inegraed saniaion sysem is heSanergy model: shared oiles are buil in slum areas, hewase is colleced daily and ranspored o a cenralisedaciliy and his is used o make compos, which can beused in agriculure (htp://saner.gy/). The Sanergycompany has buil 242 saniaion aciliies in Nairobisslums in he pas 2 years. These aciliies are run by 130local enrepreneurs who earn USD 2,000 a year o providehygienic saniaion or 10,000+ people. Anoher projeco improve saniaion in slums involves he collecion o

urine rom privae oiles.Unorunaely, here is litle pracical experience availablein he large-scale applicaion o decenralised advancedinrasrucure. A greaer ocus is hereore required ourher develop and finance inrasrucure or aecalsludge reamen (Srande e al., 2013). I a sewerageinrasrucure is already in place, he economies o scaleo large cenralised reamen plans will probably avourhis opion, in mos cases. For smaller communiies asome disance rom he sewerage nework, a smallreamen plan could be an ineresing op

PBL_2014_Towards a World of Cities in 2050_1325_0

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