Short term decisions and long-term responses of catchment systems

Nicholas Howden University of Bristol, UK

Tim Burt, Fred Worrall (Durham University, UK) Thorsten Wagener, Valentina Noacco (University of Bristol, UK) Helen Jarvie (Centre for Ecology and Hydrology, UK)

Tim Burt Fred Worrall Thorsten Wagener Valentina Noacco Helen Jarvie

2005 2006 2007 2008 2009 20100

5

10

15

con

cen

tra

tion

(m

g/l)

Dissolved Organic Carbon as C

2005 2006 2007 2008 2009 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

2005 2006 2007 2008 2009 20100

5

10

15

con

ce

ntr

atio

n (

mg/l)

Total Phosphorus as P

2005 to 2010

1980 to 2010

1980 1985 1990 1995 2000 2005 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

1980 1985 1990 1995 2000 2005 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Total Phosphorus as P

1980 1985 1990 1995 2000 2005 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Dissolved Organic Carbon as C

1950 1960 1970 1980 1990 2000 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Total Phosphorus as P

1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Dissolved Organic Carbon as C

1950 to 2010

1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Total Phosphorus as P

1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Dissolved Organic Carbon as C

1920 to 2010

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Total Phosphorus as P

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Dissolved Organic Carbon as C

1860 to 2010

Changes in agriculture

Medieval Farming Methods

Changes in agriculture

Kimball’s Dairy Farmer Magazine, July 15th 1911

Changes in agriculture

21st Century Farming

River Thames Catchment

Howden NJK, TP Burt, SA Mathias, F Worrall, MJ Whelan [2011] Nitrate pollution in intensively farmed regions: What are the prospects for sustaining high-quality groundwater?, Water Resources Research, 47, W00L02, 10.1029/2011WR010843.

River Thames Catchment

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Total Phosphorus as P

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Dissolved Organic Carbon as C

1860 to 2010

Observation…

Annual land use records from 1867

Howden NJK, TP Burt, SA Mathias, F Worrall, MJ Whelan [2011] Modelling long-term diffuse nitrate pollution at the catchment-scale: Data, parameter and epistemic uncertainty, Journal of Hydrology, 403, 337-351, 10.1016/j.jhydrol.2011.04.012.

• parish land use

• annual records (MAFF68)

Howden NJK, TP Burt, F Worrall, SA Mathias, MJ Whelan [2013] Farming for Water Quality: Balancing Food Security and Nitrate Pollution in UK River Basins, Annals of the Association of American Geographers, 103(2), 397-407, http://dx.doi.org/10.1080/00045608.2013.754672.

Nitrogen Inputs

Model to estimate nitrogen available for leaching from inputs to land and water due to: animals, fertiliser, grassland ploughing, atmospheric deposition, fixation, crop uptake and wastewater discharge.

Howden NJK, TP Burt, F Worrall, SA Mathias, MJ Whelan [2013] Farming for Water Quality: Balancing Food Security and Nitrate Pollution in UK River Basins, Annals of the Association of American Geographers, 103(2), 397-407, http://dx.doi.org/10.1080/00045608.2013.754672.

Nitrogen Inputs (a)

1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

tota

l N

-lo

ad

ing

(kg

/ h

a)

0

20

40

60

80

100

120

140

Total load

(b)

1880 1900 1920 1940 1960 1980 2000

pro

po

rtio

n o

f to

tal lo

ad

0.0

0.2

0.4

0.6

0.8

1.0

fertiliser

animals

ploughing

fixation

deposition

Nitrogen Model

0 10 20 30 40 50 600

0.002

0.004

0.006

0.008

0.01

0.012

0.014

time (years)

rela

tive c

on

ce

ntr

atio

n (

C / C

0)

Howden NJK, TP Burt, F Worrall, SA Mathias, MJ Whelan [2011] Nitrate pollution in intensively farmed regions: What are the prospects for sustaining high-quality groundwater?, Water Resources Research, 47, W00L02, 10.1029/2011WR010843.

1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

20

25

30Agriculture Inputs

kto

nn

es P

per

ye

ar

1940 1950 1960 1970 1980 1990 2000 20100

0.5

1

1.5

2

2.5

3

3.5

4Effluent Inputs

kto

nn

es P

per

ye

ar

urine

faeces

food waste

detergent

mains water

arable fertiliser

grassland fertiliser

cattle

sheep

Phosphorus Inputs

Howden NJK, TP Burt, F Worrall, HP Jarvie [in prep.] Phosphorus concentrations and fluxes in the River Thames catchment 1936 to 2014, Science of the Total Environment (Special Issue on Macronutrient Cycles), 2016.

Phosphorus Inputs and Output

Howden NJK, TP Burt, F Worrall, HP Jarvie [in prep.] Phosphorus concentrations and fluxes in the River Thames catchment 1936 to 2014, Science of the Total Environment (Special Issue on Macronutrient Cycles), 2016.

1940 1950 1960 1970 1980 1990 2000 20100

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

kto

nn

es P

per

ye

ar

Net effluent contribution

0

1

2

3

4

5

6

7

8

9

10

co

nce

ntr

ati

on

(m

g P

/l)

Phosphorus Inputs and Output: the Legacy?

Haygarth PM, HP Jarvie, SM Powers, AN Sharpley, JJ Elser, J Shen, HM Peterson, N-I Chan, NJK Howden, TP Burt, F Worrall, F Zhang, X Liu [2014] Sustainable Phosphorus Management and the Need for a Long-Term Perspective: The Legacy Hypothesis, Environmental Science and Technology, 48, 8417-8419, 10.1021/es502852s.

Conclusions… to date…

• Nitrate – animal, fertiliser and ploughing inputs important, and almost 60% of

response controlled by long-term groundwater processes with a lag time of >30 years

– if we reduce inputs by 50% now, the immediate effect would be a 20% reduction in outputs…

• Phosphorus – wastewater inputs have risen steadily and then declined after WWTD,

but there is a large legacy store of P; diffuse inputs to land do not appear to have a fluvial impact?

• Ongoing work: how do these results map to wider scales?

National-Scale Models of N, C and P Export (1 km2)

Worrall et al. [2012] - STOTEN Worrall et al. [2012] -JoH Worrall et al. [in prep]

Worrall F, H Davies, TP Burt, Howden NJK, MJ Whelan, A Bhogal, A Lilly [2012] The flux of dissolved nitrogen from the UK – Evaluating the role of soils and land-use, Science of the Total Environment, 434, 90-100, 10.1016/j.scitotenv.2012.01.035.

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

co

nce

ntr

atio

n (

mg

/l)

Nitrate as N

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Total Phosphorus as P

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 20100

5

10

15

con

cen

tra

tio

n (

mg/l)

Dissolved Organic Carbon as C

Howden NJK, TP Burt, F Worrall, SA Mathias, MJ Whelan [2011] Nitrate pollution in intensively farmed regions: What are the prospects for sustaining high-quality groundwater?, Water Resources Research, 47, W00L02, 10.1029/2011WR010843.

Nitrogen Inputs and Outputs