Impact of urbanisation on water flow

regimes and quality

Dr. M. Hutchins and Dr. T. A. Warnaars

contributions from James Miller, Scott McGrane and Xiaowei Liu

NERC Centre for Ecology & Hydrology

The UK Centre of

excellence for research

in the terrestrial &

freshwater environments

and their interactions

with the atmosphere

Our goal is to deliver solutions for

environmental problems to achieve

sustainability

Our Science Strategy

• UK National monitoring

schemes including

–Environmental Change

–Greenhouse Gases

–Water Flood/Flow

–Air Quality

–National Land use

• Over 350 Scientists and support staff

• POLLCURB investigates

how water pollution

relates to change in urban

areas, in particular that

brought about by

population growth.

Results will provide

predictions of future water

resources to help inform

decision-making.

• Focus on Thames basin

Collaborators:

POLL-CURB PROJECT

• 3-year £900k project funded by the UK NERC Changing Water Cycle programme (May 2013 start)

• Changes in Urbanisation and its Effects on Water Quantity and Quality from Local to Regional Scale

• UK population will increase by 16% in next 20 years.

Compare 2050 Thames water quality to present day?

-5

0

5

10

15

20

25

30

35

40

45

50

DO BOD Temp chl-a

Incr

ease

in d

ays p

er y

ear

Wallingford

• An increase in number of days per year having undesirable water quality by 2050 (due to drier, sunnier, warmer summers)

• Moreover, this assumes no change in population. Urban growth will put greater stress on water resources…

• The projections will be refined in POLLCURB

1. Climate model (Had-RM3)

2. Rainfall-runoff model

(Future Flows) 3. Water quality model

(QUESTOR)

Models linked together in sequence to evaluate

effects of climate change

Incr

ease

in n

um

ber

of

day

s p

er y

ear

hav

ing

un

des

irab

le c

on

dit

ion

s

Case studies: towns of Swindon and Bracknell

S S

S

S Treated sewage effluent

d) 2011 c) 2007 b) 1990 a) 1975*

• Remote sensing imagery captures land-use change. • Water flows (since 1960s) and quality (since 1980s) • 2 years monitoring of: (i) logged hydroclimatology

(15-min rainfall and discharge) and (ii) telemetric hourly water quality (YSI multi-parameter sonde).

• Water quality: pH, turbidity, temperature, conductivity, ammonium and dissolved oxygen. Also, sonde used for monthly water quality surveys at 16 other sites

Environmental data acquisition d) 2011 c) 2007 b) 1990 d) 2011 c) 2007 a) 1975* b) 1990 d) 2011 c) 2007

• Monitoring urban streams in 2 rapidly growing towns.

• Satellite land-cover data and Ordnance Survey maps will train cellular automata land-use change models.

• Water flow and water quality data will train bio-physical models (rainfall-runoff, urban water management, suspended sediments, channel hydraulics/water quality).

Research approaches

From land cover change, a metric of

fractional impervious cover drives a

rainfall-runoff model to quantify

changes in hydrological regime

Part of

Swindon

Urban water management modelling

• Water demand

• Urban drainage,

water supply and

water quality

(SWMM)

• Wastewater

treatment,

discharges to

rivers (SSDIM –

has been tested

in small Chinese

urban basins e.g.

Shenzhen River)

1. Has long-term urbanisation significantly altered the flow regime? 2. Can urban river pollution be determined by land cover data,

measures of infiltration capacity and rainfall patterns readily available from national-level datasets?

3. How do water temperature, residence time and channel hydraulics influence the fate of pollutants downstream of urban areas?

• Simplified upscaling to whole Thames basin. • At basin scale future scenarios will be defined by projections of

population growth, urban development, water demand management, water treatment and climate inputs.

• Future scenarios assessed using the meta-model and QUESTOR.

Research questions and model development

Model drivers: (1) Flow, temperature and quality data in (a) tributaries (b) effluents from sewage works, (2) Solar radiation (3) Weirs (4) Abstractions

Simulates flow routing, and pollution retention and release in short river reaches (c. 3 km) on a daily basis.

CEH weekly water quality (2009 - ) Upstream QUESTOR boundary

Tidal limit

Major urban areas outside London

LONDON

20 km

9

6 5

4

3

2

1

8

7

Model representation of River Thames (QUESTOR)

SWINDON

BRACKNELL

Other acknowledgements

Thomas Kjeldsen (Bath)

Soon-Thiam Khu (Surrey)

Simon Dadson (Oxford)

Clare Rowland, Iwona Cisowska, Luisa Doughty, Yan Weigang (CEH)

June Jones, Matt Loewenthal (EA)

Steven Loiselle, Charlotte Hall, Richard Sylvester (Earthwatch)

Banyu Putro (Royal Holloway)

OTHER CONTRIBUTORS

Contributing to Water Quality Legislation - WFD

examined how multiple effects

impact on managing

freshwater ecosystems

Integrated project on adaptive

strategies to mitigate impacts of

climate change on European

freshwater ecosystems

Restoring river ecosystems in Europe:

the REFORM project will provide

tools to support cost-effective

implementation of restoration

measures and monitoring

WATCH: A Global Project

•To integrate modelling of the water cycle into global and regional climate models

•evaluate how the global water cycle and its extremes respond to future drivers of global change

•develop a modelling and data framework to assess the future vulnerability of water as a resource

Estrogen prediction in Yellow River using CEH GWAVA model

Lijin

Tongguan

Lanzhou

• What are the likely impacts of increased urbanisation on river estrogen concentrations?

• Currently ~50% of population STP connection

• Natural flows successfully simulated in 1950s. More recent simulations highlight need to refine representation of water demand.

• Gwava: 50x50 km grid resolution. 9 flow gauges for model testing. Estrogen concentrations in 2008

• Estrogen loads based on: (i) Chinese effluent observations, or, (ii) excretion and removal rates based on UK data

0

200

400

600

800

1000

1200

1400

1600

1800

1952 1953 1954 1955 1956 1957 1958 1959 1960

Flo

w (

m3/s

)

Year

TONGGUAN Estimated flow

Measured flow

12.2%

27.1% 26.7%

4.6%

18.3%

5.22%

2.14%

10.6%

RSD: 20.9%

Thank You