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© University of Reading 2008

Modelling, GIS andremote sensingPart 1 –Integrated catchment modelling05 November 2008Andrew Wade (a.j.wade@reading.ac.uk)Department of GeographyThe University of Reading, UK

Introduction

• Principles– Issues and complexity– Water resource management– Modelling approach

• Examples– INCA­N– Inclusion of remote sensing data– Farming– Effluent– Climate change

• Limitations of models

• Summary

3

Why model?• Barnsley 2008, Environmental Modelling, Chapter 1• Building a well­designed model forces one to examine

the– Component elements of an environmental system– Processes and structures that govern the relationships and

interactions between them– Spatial and temporal scales over which the processes and

structures operate

• Scenario analysis for management

DefinitionsSpatial Scale

– Plot: 1 m2

– Small­scale, research: 10 km2

– Meso­scale: 100 km2

– Large­scale: 5 000 km2

– Regional­scale: 20 000 km2

– National­scale: 250 000 km2

(UK based definitions)

Loch Muick, Aberdeenshire

Little Ouse, Norfolk

Nitrogen Issues

Steinkreuz, southern GermanyHaygarth PM, Jarvis, SC. 2002.

Neal et al. 2005

Neal et al. 2003

River Dee, Aberdeenshire

Variability

Newson MD. 1997.

Land, Water and Development:River basin systems and theirsustainable management

Routledge, 2nd Edition, pp 351

Scale Problem

point

1 m

10­100 km

National

Equifinality

N Models: Upland• MAGIC and MERLINAdvantages

– Acidification– Dynamic– Process representation

Disadvantages– High data requirements– Upland systems– MAGIC has simplistic N  component

N models: Agricultural• SUNDIALAdvantages

– Dynamic– Simulate hydrological and chemical processes

Disadvantages– High data requirements– Field scale only

N Models: Empirical• Export Co­efficient

Advantages– Low computational requirement– Easy to apply at different spatial scales

Disadvantages– No hydrological or chemical process representation

N models: In­stream• QUASARAdvantages

– Dynamic– In­stream processes and pollutant routing

Disadvantages– In­stream only

What is INCA?• Integrated Catchment model

• N dynamics in complex river systems– Terrestrial

– In­stream

• Point and diffuse

• Process­based, mass balance

• Daily

• Simulates NO3, NH4

Wade AJ, Durand P et al.  2002.

Whitehead et al. 1998

INCA screen shot

GIS Database

INCA

How does the model work?

Land Cell: Hydrological Model

QuickSoil

Groundwater

Quickflow

Throughflow

Groundwater flow

P AET

NO3

Groundwater Zone

NH4

Urban wasteto River

NitrogenFixation

Ammonium +Nitrate deposition

Ammonium +Nitrate fertiliser

NO3 NH4

nitrification

Organic N

Netmineralisation

NitrateAddition

Plantuptake

AmmoniumAddition

Plantuptake

Reactive Soil Zone

denitrification

Leachingto river

Leachingto river

NO3

Groundwater Zone

NH4

Urban wasteto River

NitrogenFixation

Ammonium +Nitrate deposition

Ammonium +Nitrate fertiliser

Urban wasteto River

NitrogenFixation

Ammonium +Nitrate deposition

Ammonium +Nitrate fertiliser

NO3 NH4

nitrification

Organic N

Netmineralisation

NitrateAddition

Plantuptake

AmmoniumAddition

Plantuptake

Reactive Soil Zone

denitrification

Leachingto river

Leachingto river

Land Cell: Hydrological Model

QuickSoil

Groundwater

Quick flow,qquick

Throughflow,

(1­ )qsoil

Groundwaterflow, qgw

qsoil

qsoil

quick

quicksoilquick

RTqq

dtdq −

=α

soil

soileffsoil

RTqp

dtdq −

=

gw

gwsoilgw

RTqq

dtdq −

=β

P AET

NO3

Groundwater Zone

NH4

Urban wasteto River

NitrogenFixation

Ammonium +Nitrate deposition

Ammonium +Nitrate fertiliser

NO3 NH4

nitrification

Organic N

Netmineralisation

NitrateAddition

Plantuptake

AmmoniumAddition

Plantuptake

Reactive Soil Zone

denitrification

Leachingto river

Leachingto river

NO3

Groundwater Zone

NH4

Urban wasteto River

NitrogenFixation

Ammonium +Nitrate deposition

Ammonium +Nitrate fertiliser

Urban wasteto River

NitrogenFixation

Ammonium +Nitrate deposition

Ammonium +Nitrate fertiliser

NO3 NH4

nitrification

Organic N

Netmineralisation

NitrateAddition

Plantuptake

AmmoniumAddition

Plantuptake

Reactive Soil Zone

denitrification

Leachingto river

Leachingto river

100.103104

103864003.

100.3

26

116

14

6213

CVolNOSC

VolNHSC

VolNO

SSCVol

NOqInput

dtdNO soilsoilsoilsoil

+−+

−−=

OutputPlantUptake

nitrification denitrificationNon­biologicalfixation

Temperature dependencies

Rate coefficients are temperature dependent

where θs = soil temperature

where θa = air temperatureC16 is the maximum temperature difference between winter and summer

(Green and Harding, 1979)

)20(047.1 −= θnn CC

−=

365.

23sin16

daynoCas πθθ

reach

instreamininstream

RTqq

dtdq −

=

86400breach

reach aqLRT =

VolqNHC

VolqNO

CVolNOq

Inputdt

dNO

instreaminstream

instreaminstream

ireach

instreaminstreamstream

instream

864004

864003864003.3

10

11

+

−−=

Upper Kennet Catchment

River Kennet at Mildenhall

Lambourn

Sewage Treatment Works

Atmospheric N Deposition Model

MATADOR­N (National Power plc)+

Deposition Velocities (David Fowler, ITE)+

Land Use=

Atmospheric N Deposition

Kg ha­1 yr­1

0.2 ­ 4.34.4 ­ 8.48.4 ­ 12.412.4 ­ 16.516.5 ­ 20.620.6 ­ 24.824.8 ­ 28.728.7 ­ 32.8

Total Nitrogen Deposition

Calibration

Shaw

Boxford

East Shefford

Demo

Advantages and disadvantages ofthe INCA­N approach

Advantages• Process­based, dynamic, spatial­variability• Catchment­scale, range of issues• Terrestrial and in­stream• Data readily available• User­interface• Reach and land­use based output• Quick to run• Links to aquatic biology (INCA­P)• European­wide use by research groups• Common structure for variants (Sed, N, P, C, Hg, Mine)

Disadvantages• Point­sources on tributaries• Fully­distributed routing• Relatively data intensive• GIS and modelling skills• Equifinality

Advantages and disadvantages ofthe INCA­N approach

Summary• Range of nutrients (nitrogen) issues• Complexity of catchments• Need for integrated modelling• Example of INCA­N• Demo• Scenarios

Next ­ Uncertainty• What makes uncertainty?• How can remote sensing and GIS

help?